Highbush Blueberries

General Information

There are two types of blueberries grown in New England. Highbush blueberry (Vaccinium corymbosum) is discussed here. For information on lowbush blueberry (V. angustifolium, V. myrtilloides), contact Lily Calderwood at the University of Maine Cooperative Extension in Orono, Maine.

New England is considered the northern edge of the climatic zone in which highbush blueberries can be grown. As a result, a number of disease problems associated with cold stress, particularly canker diseases, are more common here than in other blueberry growing areas. High soil acidity (low pH) and relatively high organic matter are essential for optimum production.

Blueberry has very specific soil requirements, dictated by its unique root structure. The blueberry root system is composed primarily of fine, fibrous roots near the soil surface. These fibrous roots lack root hairs, so the root system has a relatively low absorptive capacity. Blueberry roots are unable to penetrate compacted soils and have limited tolerance to excessively wet or dry soils. The shallow root system is sensitive to both high and low temperature extremes.

Ideal blueberry soil is a well-drained, yet moist sandy loam soil with a pH of 4.5 to 5.2. If pH reduction is necessary, elemental sulfur can be broadcast and incorporated in advance of planting. Soil organic matter levels should be augmented through the use of pre-plant green manure cover crops and the addition of peat moss at planting. In addition, a layer of organic mulch (wood chips, bark, sawdust, pine needles) 3 to 4 inches thick helps to protect roots from high temperature injury in summer and cold temperature injury in winter as well as reduce moisture stress and suppress weeds.

Fertilizer is generally applied in a split application, reducing the risk of root burn and pollution runoff that can accompany a single large application. Half of the total fertilizer needed is applied at bloom and the other half is applied one month later. Late applications of nitrogen fertilizers (after July 1) should be avoided, because they can promote fall growth, delay hardening, and increase chances of winter injury. Since nitrogen is generally the only nutrient needed, ammonium sulfate (21% N) or urea (45% N) are used as the principal fertilizers.

Proper pruning maintains the productivity of highbush blueberry plantings. Young bushes do not need pruning during the first 2-3 years, but after that, bushes should be pruned annually when dormant, prior to budbreak in the spring. Damaged or old canes that are no longer producing strong new wood should be removed at ground level. The goals of pruning are to establish a balance of canes (or main stems) of different ages, to remove non-productive wood, and to allow good airflow to minimize pest and disease problems. Check with your Cooperative Extension office for details of proper varieties and cultural techniques for highbush blueberry.

Table 28. Recommended optimal soil characteristics for growing blueberries.
Soil Characteristic Desirable Range*
pH 4.5 - 5.2
Organic matter 4 to 7%
Phosphorus 20 - 30 ppm
Potassium 100-120 ppm
Base Saturation 3.0-5.0
Magnesium 100-120 ppm
Base Saturation 2.0-4.0
Calcium 800 - 1000 ppm
Base Saturation 20-30
*Desirable range will vary with soil type (sand, silt, or clay), soil organic matter, and pH.


 

Table 29. Amount of sulfur (in lb/100 sq ft)a required to lower soil pH for blueberries.
Desired ph value for blueberries
  4.5 5.0
Present soil pH Sand Loam Clay Sand Loam Clay
4.5 0.0 0.0 0.0 -- -- --
5.0 0.4 1.2 1.4 0.0 0.0 0.0
5.5 0.8 2.4 2.6 0.4 1.2 1.4
6.0 1.2 3.5 3.7 0.8 2.4 2.6
6.5 1.5 4.6 4.8 1.2 3.5 3.7
7.0 1.9 5.8 6.0 1.5 4.6 4.8
7.5 2.3 6.9 7.1 1.9 5.8 6.0
a To convert to lb/A, multiply by 435
Table 30. Number of blueberry plants per acre at different spacings.
Feet Between Spacing Between Rows
PLANTS IN ROW 8 FEET 10 FEET 12 FEET
4 1,361 1,089 908
5 1,089 870 726
6 908 726 605
Table 31. Critical nutrient values for blueberry tissue analysis.
Element Deficient Below Normal Normal Above Normal Excessive
N (%) 1.65 1.70 1.90 2.10 >2.50
P (%) 0.05 0.06 0.10 0.18 >0.22
K (%) 0.35 0.40 0.55 0.65 >0.80
Ca (%) 0.35 0.40 0.60 0.80 >1.00
Mg (%) 0.18 0.20 0.25 0.30 >0.40
Mn (ppm) 45 50 250 500 >650
Fe (ppm) 65 70 200 300 >400
Cu (ppm) 4 5 11 15 >20
B (ppm) 29 30 40 50 >65
Zn (ppm) 14 15 25 30 >35

Diseases

Fruit

Mummy Berry (Monilinia vaccinii-corymbosi): Mummy berry is an important disease in many parts of New England, and its severity varies from year to year. It is caused by a fungus that attacks new growth, blossoms, foliage and fruit, and it can cause extensive losses.

The fungus overwinters in mummified fruit on the ground. In spring, the mummies form cup-shaped structures called apothecia. Apothecia produce spores that infect young tissue and cause rapid wilting. This is called leaf and twig blight, or shoot blight. These symptoms are difficult to distinguish from frost injury or Botrytis shoot blight. These first infections form more spores, which are spread by rain, wind and bees to blossoms and other young tissue. The fungus then infects and invades developing fruit. Infected fruit become malformed and turn salmon-colored or grey by midsummer. By fall, these fruit drop to the ground, ready to produce apothecia the next spring.

Management: Cultural controls can be used to reduce inoculum levels. In very small plantings, infected fruit can be hand-picked or mummies can be raked up and removed. On a larger scale, mummies can be buried by covering with a new layer of mulch at least 2” thick. Combining cultivation between rows with an application of 50% urea prills in the spring can also destroy mummies. The cultivation should be done just as apothecia start to emerge in the spring, but not before blueberry bud-break. Urea should not be applied to areas where there is standing water, as this may cause fertilizer burn. Apply urea to drier parts of the field and go back to the wetter areas later.

Cultivars  differ in susceptibility to both phases of mummyberry infection: shoot blight and fruit infection. Those that are most resistant to the shoot blighting phase of the disease include Bluejay, Darrow, Duke, Elliot, and Toro. Cultivars that appear to be the most susceptible are Bluegold, Blueray, Coville, Legacy, Northblue, Northsky, Patriot, and Sierra. Cultivars that are consistently resistant to the fruit infection phase include Northsky, Reka, Northblue, Bluegold, Bluejay, Weymouth, and Patriot. Those that are highly susceptible include Berkley, Herbert, Lateblue, Bluehaven, Elliot and Elizabeth and Blueray.    Resistance to fruit infection appears to be unrelated to resistance to shoot blight, and weather factors can also affect cultivar response to the disease.

Several fungicides are labeled for use against this disease. Labeled materials and state registrations change annually. See pest management schedule for recommended materials and timing.

Botrytis Blight/Gray Mold (Botrytis cinerea): As with other small fruits, Botrytis primarily affects blossoms and ripening fruit, although under certain circumstances the fungus can cause shoot blight as well. Infection occurs largely during bloom on flowers. The fungus survives the winter on dead twigs and on crop debris, and outside the field on other plants. It is present every year, but only causes severe damage during cool, wet periods lasting several days. The most critical period for infection is during bloom. Disease is most severe where excessive nitrogen has been used, where air circulation is poor, or where frost has injured blossoms. Infected berries typically have a gray cast of mycelium and spores which gives the disease its name. Stem symptoms are hard to distinguish from those caused by Phomopsis. Consult your state university plant diagnostic lab for proper disease identification. Varieties possessing tight fruit clusters (for example, Weymouth, Blueray and Rancocas) are particularly susceptible to Botrytis.

Management: When weather or history indicates that Botrytis will be a problem, fungicides should be applied, starting at mid- bloom, with subsequent sprays at 7-10 day intervals through petal fall. See pest management schedule for recommended materials and timing.

Anthracnose (Colletotrichum acutatum): This fungus primarily damages fruit, but may also infect twigs and spurs. Infected fruit often exhibit a soft, sunken area near the calyx-end of the fruit. Salmon-colored spores spread to “good” fruit during and after harvest, causing significant post-harvest losses. The disease is especially prevalent during hot muggy weather and frequently occurs post-harvest.

Anthracnose overwinters in dead or diseased twigs, fruit spurs, and cankers. Spores are released in spring, and are spread by rain and wind. Blossoms, mature fruit and succulent tissue are infected, and spores may be spread from these infections. Infected blossom clusters turn brown or black. Infected fruit show salmon-colored spore masses at the blossom end. Stem cankers are rare, but are about 1/8” in diameter, with raised purple margins when they are present. Young girdled stems die back, resulting in a brown withering of leaves. Bluecrop, Bluetta, Chanticleer and Spartan are particularly susceptible to anthracnose. Elliot and Weymouth appear to have good resistance.

Management: Anthracnose is controlled primarily through the use of fungicide applications, though pruning for optimal air circulation and clean harvesting are beneficial. Old canes and small twiggy wood should be cleared out in order to increase air circulation around the fruit clusters. See pest management schedule for recommended materials and timing.

Table 32. Highbush blueberry varieties - growth characteristics & disease resistance for New England.
  Disease Resistance b  
Variety Hardiness Zonea Season

mummyberry

Shoot

mummyberry

Fruit

phomopsis fusicoccum

powdery

mildew

anthracnose Growth Habit
Aurora 4 very late - - - - - S spreading
Berkeley 5 mid - S VS S R VS upright bushy
Bluecrop 4 mid - MR - VS S VS upright open
Bluegold 4 late S R - - - S compact
Bluejay 4 early mid R R S - - S upright open
Blueray 4 mid S S - S S VS upright open
Bluetta 3 very early MR MS R - - S low bushy
Bonus 4 mid - - - - - S upright open
Brigitta 4 late - - - - - MR upright open
Cara's Choice 6 mid - - - - - S compact spreading
Chandler 4 mid late - - - - - - spreading
Chanticleer 5 very early - - - - - VS upright
Chippewa 3 mid - - R - - VS upright half high
Collins 4 early mid - MS - - S S moderately upright
Coville 5 late mid S S - VS MR VS upright open
Darrow 5 late R MS - - - - low bushy
Draper 5 early mid - - - - - - upright tall
Duke 5 early R MR S - - S upright open
Earliblue 5 very early - MS VS VS R S upright bushy
Elizabeth 4 mid late MR S - - - MR spreading
Elliott 4 very late R MS R - - MR upright bushy
Hannah's Choice 6 very early - - S - - MR upright open
Jersey 4 late mid MR MS S VS MR S upright bushy
Lateblue 4 very late MR S - - - S upright open
Legacy 5 mid late S MS S - - MR upright spreading
Liberty 3 very late -

-

- - - - upright
Meader 4 mid - MR - - - S upright open
Nelson 4 late - MS - - - S upright open
Northblue 3 early S R - - - S half high
Northcountry 3 early mid - - - - - S half high
Northland 3 mid - MR - - - S half high
Northsky 3 mid late S R R - - S very low bushy
Patriot 3 early mid S MR - - - S compact open
Polaris 3 early - - - - - VS spreading half high
Reka 4 early - R - - - S upright
Rubel 4 mid MR MS R MR - S upright open
Sierra 5 early mid S VS - - - S upright open
Spartan 5 early - MR S - - VS upright open
St.Cloud 3 late - - - - - VS upright half high
Sunrise 4 early mid MR MR - - - S low bushy
Toro 4 mid R MS - - - S upright open
Weymouth 4 very early - MR VS - - R low bushy

a Refers to USDA Hardiness Zones: http://planthardiness.ars.usda.gov/PHZMWeb/

b R= resistant, MR= moderately resistant, MS= moderately susceptible, S= susceptible, VS= very susceptible, "-"= unknown.
For information on sources and further descriptions of cultivars listed above, go to the Cornell Nursery Guide for Berry & Small Fruit Crops at:

http://fruit.cornell.edu/

Stems and Foliage

Fusicoccum Canker or Godronia Canker (Godronia cassandrae): Fusicoccum canker is caused by a fungus that infects blueberry stems causing dieback and plant decline. Losses from this disease can be serious. The fungus overwinters as mycelium in cankers on living plants. In Massachusetts, spores are released from March to mid-July, and new infections can occur throughout the growing season. Spores are disseminated by rainwater. New infections occur following rains when tender new tissue is present and temperatures are 50-72˚ F. Cold stress may play a part in increasing disease damage. Leaves turn reddish-chocolate colored and often hang on late into the fall.

Symptoms of Fusicoccum canker are similar to Phomopsis canker on blueberry. The most unique symptom is a red-maroon-brown lesion centered around a leaf scar. A bullseye pattern often results. As the lesion enlarges, the margin remains red and the center turns gray and dies. On young (1-2 year old) stems, extensive stem infections quickly lead to flagging and dieback of the entire stem. On warm, dry days shoots will suddenly wilt and die due to the stem girdling.

Management: Sanitation is essential. A fungicide program should be used where incidence of the disease is high. Apply at 2-week intervals from late dormancy to petal fall. Varieties differ in their resistance to this disease. See pest management schedule for recommended materials and timing.

Phomopsis Twig Blight (Phomopsis vaccinii): This disease may be the most prevalent of the canker diseases. The fungus, Phomopsis, causes stem damage similar to that caused by Fusicoccum.

Spores from old cankers are released in spring and, to a limited extent, in summer. Most spores are released from bud swell to petal fall, and none are released after September 1. Rain is necessary for spore release, and temperatures from 70-80˚F encourage infections. The disease is most severe after winters in which mild spells are interspersed with cold weather. Periods of hot, dry weather during the growing season probably also predispose plants to a certain degree. The fungus overwinters in infected plant parts.

Symptoms first appear on smaller twigs and spreads into larger branches and may affect the crown. It is possible for Phomopsis to spread downward in injured canes to the crown and then progress upward on new canes. This rarely occurs, usually only where the crown itself has been injured after a particularly severe winter, or in highly susceptible varieties. Younger tissue may show no symptoms at first, and then exhibit rapid wilting and dieback. Stem lesions are similar to those caused by Fusicoccum but generally lack the bullseye pattern. The disease also causes premature ripening of berries. Leaf spots have  been observed where disease is particularly severe, and the fungus may also cause fruit rot, although this is rarely observed in New England. Most commercial cultivars are susceptible to Phomopsis canker.

Management: Since mechanical damage and cold stress seem to be necessary for Phomopsis infection, avoid unnecessary cultivating, and do not fertilize after July 1st. Prune weakest canes to the ground. Avoid drought stress by keeping plants well-watered through prolonged periods of dry weather in summer. The cultivars Bluetta, Elliot, and Rancocas have been reported to have partial resistance to Phomopsis. Fungicide applications may also be beneficial. See the pest management schedule in this chapter for recommended materials and timing.

Coryneum Canker (Coryneum microstictum): This canker disease appears to be uniquely situated in the southeast part of New England. No estimates of loss from the disease are available; it does not occur regularly and is often found with other canker fungi.

The symptoms are similar to other canker diseases. The cankers are commonly seen on sunscalded or cold-stressed bushes where the fungus produces spores. Wounds are apparently necessary for infection.

Management: Cultural practices that maintain vigorous growth without stimulating too much succulent growth are recommended for this canker disease as well as the others. (See the Phomopsis section). No chemical controls are specifically recommended.

Powdery Mildew (Microsphaera vaccinii): This disease affecting primarily the leaves is uncommon in New England, although localized outbreaks of the disease occur occasionally. Symptoms include a white fungal growth on upper leaf surfaces, puckering of leaves, and reddish leaf spots. When severe infection occurs, defoliation may occur.

Management: Some cultivars are more resistant than other cultivars. Well-timed fungicides will also control the disease, but are probably not necessary in New England.

Witches’ Broom: Witches’broom is a relatively minor disease of highbush and lowbush blueberries and other Vaccinium spp. in North America and is caused by the fungus Pucciniastrum goeppertianum. Diseased blueberry plants have broom-like masses of swollen, spongy shoots with shortened internodes and small leaves. Brooms usually begin to develop during the year following infection and then persist for many years, producing infected new growth each spring. Young stems on broom are initially reddish or yellow, but as the season progresses become brown and shiny, then dull, and eventually dry and cracked. Although heavily infected plants produce no fruit, disease incidence is usually so low that crop losses are negligible. Nearly 100% of blueberry plants may be infected in fields located near fir (Abies spp.) trees, the alternate host of the rust fungus that causes witches’ broom.

Management: Because the pathogen is perennial and systemic in blueberry crowns and rhizomes, pruning does not eliminate witches’ broom. The best control strategy is to eradicate fir trees within 1200 feet of blueberry plants, though this may not be practical. Infected bushes should be rogued out.

Blueberry Leaf Rust: Is a minor disease of blueberries caused by the rust fungus, Pucciniastrum vaccinia. In early spring to summer, spores from hemlocks (alternate host) are dispersed by wind and infect young blueberry leaves. The disease first appears as small yellow (chlorotic) spots on the upper surface of young blueberry leaves. As the infection progresses spots turn a reddish-purple color with a discrete yellow halo. On the underside of leaves, spots have a distinct brown edge with pustules of yellow-orange spores in the center. These spores are capable of causing new infections throughout the growing season. 

Management: Plant disease resistant plants. Bluecrop, Burlinton, Collins, and Weymouth are very resistant to leaf rust. Fungicides are generally not needed to manage leaf rust, but if symptoms appear early in season consider applying a fungicide to suppress additional infections. See pesticide table for fungicide recommendations.

Roots

Phytophthora Root Rot (Phytophthora cinnamomi): This disease is usually associated with poorly drained areas in a field. Symptoms are noted on the roots and on the above-ground portions of the plant. The very fine absorbing roots turn brown to black; larger diameter roots may also be discolored. In severely infected bushes, the entire root system is reduced in stature and is totally black. Above-ground symptoms include chlorosis and reddening of the leaves, smaller leaves, defoliation, death of branches or entire canes, stunting, and death of the entire bush. The disease may be present in a few infected plants scattered throughout the planting or localized in group of plants in low-lying areas. The disease is worst where plants are growing in heavy clay soils.

Phytophthora cinnamomi, in addition to attacking blueberry, attacks several other Ericaceous hosts, including rhododendron, azalea, and cranberry. Lowbush blueberry appears to be immune. This species of Phytophthora is not an important pathogen on any other small fruit covered in this guide. The fungus thrives in wet soils and can survive for long periods of time.

Management: The disease is best avoided through careful site selection. Heavy soil that becomes waterlogged or suffers from a high water table should be avoided. If a wet site is unavoidable, water drainage should be improved. Plant growth may be improved by growing on raised beds. Most varieties are susceptible to the disease, although some varieties may better tolerate infections. Bluecrop and Weymouth are two varieties that have shown promise. Mefenoxam (Ridomil Gold) can be used at planting if problems with Phytophthora root rot are anticipated. It can also be applied as a drench to established plantings. If needed, Mefenoxam should be applied twice per growing season. However, the best strategy is to plant on well drained sites or improve soil drainage.

Armillaria Root Rot (Armillaria mellea and A. ostoyae): Although this disease is uncommon, it can cause serious injury to plants in fields where the fungus is present in the soil. To date, the disease has only been found in fields that were originally pine/oak forests. The fungus survives in soil on root pieces of susceptible hosts (pine, oak, etc.). The fungus can infect bushes through root grafts and can survive on wood chip mulches. Mulches should be carefully selected so that fungal inoculum is not introduced into the field.

Infected bushes usually decline over several growing seasons, and their symptoms can be confused with those caused by winter injury, Phomopsis twig blight, or a nutritional imbalance. Affected plants are chlorotic, have smaller-than-usual leaves, and are more susceptible to other stresses than healthy plants. Branches may suddenly wilt, followed by plant mortality in some instances. The disease may be found throughout an entire field, or it may be confined to one or a few areas. The most important diagnostic characteristic is the presence of the fungus: white mycelial fans underneath the outer bark or the crown of the plant, black rhizomorphs (resembling shoestrings) attached to the roots or the trunk, and yellowish-brown mushrooms produced at the base of the plant in late summer or early autumn.

Management: The disease is best avoided by thoroughly discing soil where blueberries are to be planted, and by removing as many root fragments as is possible. If possible, leave the field fallow three years after trees have been removed. Soil sterilants or fumigants are effective at killing the fungal inoculum. The disease is very difficult to control once it is present in a field. Dead or dying plants should be removed, and adjacent plants should be inspected at the soil-line for mycelial fans or rhizomorphs. Remove any plants that have signs of the pathogen. Wood chip mulch should be removed from infection “hot spots.” Although spot fumigation might be effective, chemical controls are usually not feasible in fields where the disease is present. Most varieties are probably susceptible to the disease.

Viruses and Mycoplasma-like Organisms (MLO)

Blueberry Shoestring Disease: This viral disease was originally described in New Jersey. In Michigan, the disease has been found in 0.5% of the bushes; an assessment has not been done for potential losses due to the virus. Blueberry shoestring disese is transmitted by aphids.

The most common symptom is an elongated reddish streak along the new stems. The leaves may also show red banding or a red-purple oak-leaf pattern. Diseased leaves are narrow, wavy and somewhat sickle-shaped. Flowers may be red-streaked, and berries turn purple prematurely. Within a few years, berry production drops dramatically.

Management: Other than buying disease-free plants, destroying wild plants near the planting, and removing diseased plants, controls do not exist. As with most virus diseases, the best controls are preventing disease introduction, and detecting the disease early. The virus has been observed most often in Jersey, Blueray, Burlington, Cabot, Earliblue, Elliott, Jersey, June, Rancocas, Rubel, Spartan and Weymouth. Bluecrop and Atlantic are resistant to the disease. Varieties with moderate resistance include Draper, Aurora, Liberty, Legacy and Brigitta. Aphid control is most important in fields containing varieties that are susceptible to shoestring virus. If fields of these varieties contain symptoms of shoestring, aphid control should be a priority during the season and infected bushes showing symptoms should be tagged and removed in the late fall once aphids are not able to be spread through the field during removal.

Blueberry Stunt: This disease was originally thought to be caused by a virus but it is now known to be caused by a mycoplasma-like organism or phytoplasma. The only known carrier is the sharp-nosed leafhopper, though other vectors probably exist.

Symptoms vary with the stage of growth, time of year, age of infection, and variety. Symptoms are most noticeable during mid-June and late September. Affected plants are dwarfed with shortened internodes, excessively branched, low in vigor with small downward cupped leaves which turn yellow along the margins, and between the lateral veins, giving a green and yellow mottled appearance. These mottled areas will turn brilliant red prematurely in late summer, although the midrib remains a dark bluish-green. Fruits on infected bushes are small, hard, lack flavor, ripen late if at all, and remain attached to infected plants much longer than they would on healthy plants.

Management: Diseased bushes cannot be cured; these must be removed from the field as soon as a diagnosis has been made. Removing diseased plants may spread the disease by dislodging leafhoppers, causing them to hop to neighboring healthy bushes. Infected bushes should be sprayed with an appropriate insecticide before infected bushes are removed. Using virus indexed plants is also helpful. Bluetta, Jersey, and Weymouth are particularly susceptible, whereas Rancocas is resistant.

Blueberry Red Ringspot: This is the most widespread viral disease in New Jersey at the present time. The symptoms are very distinctive, including red spots, rings and oak-leaf patterns which usually appear on the older leaves in late June or July. Fruit production is seriously reduced and berries become pockmarked and unattractive. Blueray, Bluetta, Burlington, Cabot, Coville, Darrow, Earliblue, and Rubel are susceptible to the disease, whereas Bluecrop and Jersey are resistant or tolerant. Infected bushes must be rogued out.

Blueberry Mosaic: Like some of the previously described viruses, this virus is probably indigenous in wild blueberry plants. Infected plants become unproductive. Leaves are brilliantly mottled with yellow, yellow-green and pink areas. Not all leaves show symptoms and some branches on an affected bush may be symptomless. It may take several years for a bush to show symptoms. The disease appears most commonly in Herbert and Stanley; most varieties appear to have field resistance to the virus. Infected bushes cannot be cured and must be removed promptly.

Blueberry Scorch (formerly Sheep Pen Hill Disease): This disease has recently been found in fields in Massachusetts and Connecticut. It is a serious problem in fields in New Jersey (it was originally found in a field in the Sheep Pen Hill area). Symptoms fluctuate greatly from year to year, and symptoms are worst during excessively wet years.

The disease is characterized by dieback of blossoms and young vegetative shoots in the spring followed by a flush of growth in summer and development of a necrotic line pattern in fall foliage. Roots suffer injury, and fruit production can be greatly impacted. In New Jersey, blueberry scorch virus has been shown to cause severe symptoms on all varieties except Jersey.

Management: The causal agent is a flexuous rod-shaped virus and is vectored by aphids. The sole control strategy is to remove affected bushes, though control of aphids is also important in managing any spread of this disease. Effective aphicides should be applied before removing infected bushes, to reduce further spread caused by aphids moving to healthy bushes.

Table 33. Fungicide efficacy for blueberry diseases
Fungicide FRAC Group ACTIVE INGREDIENT Mummyberry Phomopsis

Powdery

Mildew

Anthracnose Botrytis Phytophthora
Root Rot
primary secondary
Abound& 11 azoxystrobin ++ + ++ ++ +++ ++ 0

Actinovate

BM02 Streptomyces
lydicus
(strain WYEC 108)
++ + -- -- -- -- --
Aliette 33 aluminum tris 0 0 +/++ 0 ++ 0 ++
Badge SC M01

copper oxychloride,

copper hydroxide

0 0 -- -- + + 0
BotryStop BM02 Ulocladium oudemansii (strain U3 ) -- -- -- -- -- +++ 0
Bravo M5 chlorothalonil +/++ + ++ + ++ ++ 0
Captan M4 captan + + + + ++ + 0
Captec M4 captan + + + + ++ + 0
CaptEvate 17, M4 fenhexamid,
captan
+/++ + ++ + ++ ++ 0
Copper products M01 copper hydroxide 0 0 ++ -- -- +/++ 0
Cueva M01 copper octanoate 0 0 0 0 0 +/++ 0
Cuprofix M01 basic copper sulfate 0 0 ++ 0 -- +

--

Double Nickle BM02 Bacillus
amyloliquefaciens
(strain D747)
++ ++ -- -- -- -- --
Elevate 17 fenhexamid + + + + 0 +++ 0
Indar 3 fenbuconazole ++/+++ ++/+++ +++ -- 0 -- 0
Inspire Super 3,9 difenoconazole,
cyprodinil
+++ +++ -- -- -- -- --
JMS Stylet Oil/Organic JMS Stylet Oil NC paraffinic oil -- -- -- ++ -- -- 0
Kocide/Kocide 2000-O/Kocide 3000/Kocide 3000-O M01 copper hydroxide 0 0 ++ -- -- -- 0
Kumulus DF M02 sulfur -- -- -- ++ -- -- --
LifeGard P06 Bacillus
mycoides
(isolate J)
++ ++ 0 0 ++ ++ 0
Miller Lime Sulfur% M02 calcium
polysulfide
0 0 ++ 0 0 0 0
Luna Sensation 7,11 fluopyram,
trifloxystrobin
-- -- +++ +++ +++ +++ 0
Luna Tranquility 7,9 fluopyram,
pyrimethanil
+++ +++ -- +++ -- +++ 0
Microthiol Disperss M02 sulfur -- -- -- ++ -- -- 0
MilStop SP NC potassium
bicarbonate
-- -- 0 ++ -- + 0
Omega 29 fluazinam +/++ +/++ ++ -- ++ 0 0
Oranil M05 chlorothalonil +/++ + ++ + ++ ++ 0
Orbit, Tilt 3 propiconazole ++/+++ +/++ +++ +++ 0 0 0
Oso 19 polyoxin
D zinc salt
++ ++ -- -- -- ++ 0
OxiDate NC hydrogen peroxide,
peroxyacetic acid
-- -- 0 + -- -- 0
PERpose Plus NC hydrogen peroxide -- -- 0 + -- -- 0
Ph-D 19 polyoxin
D zinc salt
++ ++ -- -- -- -- --
pHorcePhite P07 phosphorous acid 0 0 0 -- + -- ++
Pristine 7, 11 boscalid, pyraclostrobin +/++ ++ ++/+++ -- +++ ++/+++ 0
Prophyte P07 phosphorous acid 0 0 0 -- + -- ++
Proline 3 prothioconazole ++/+++ ++/+++ ++ -- -- ++ 0
PropiMax 3 propiconazole ++ ++ -- -- + + 0
QuiltXcel 3, 11 azoxystrobin,
propiconazole
++ ++ ++ -- ++ ++ 0
Quash 3 metconazole ++/+++ ++/+++ ++/+++ -- ++ ++ --
Regalia P05 Reynoutria
sachalinensis
+/++ +/++ -- + -- -- --
Rendition NC hydrogen peroxide, peroxyacetic acid -- -- 0 + -- -- 0
Ridomil Gold 4 mefenoxam 0 0 0 0 0 0 +++
RootShield BM02 Trichoderma
harzianum
(strain T-22)
0 0 0 0 0 0 ++
RootShield PLUS+ BM02 Trichoderma
harzianum
(strain T-22), Trichoderma virens (strain G-41)
0 0 0 0 0 0 ++
Serenade + Nu-film BM02, NC Bacillus subtilis (strain QST 713), pinene polymers ++ + + -- -- -- ++
Switch 9, 12 cyprodinil,
fludioxonil
0/+ 0 0 + ++/+++ +++ 0
Ziram M03 ziram + + ++ 0 ++ +/++ 0

0=not effective; +=slight effectiveness; ++=moderate effectiveness; +++=very effective; --=insufficient data

=OMRI listed for organic production; go to http://www.omri.org/ for details.

Products with the same FRAC code have active ingredients with the same mode of action. Repeated use of products with the same mode of action should be avoided to reduce the risk of development of chemical resistance by the pest and reduced efficacy of the pesticde. Fungicides with two FRAC codes contain active ingredients with two different modes of action. For more information on FRAC codes and managing fungicide resistance, go to https://www.frac.info/.

* Restricted use material; pesticide applicators license required.

& This material is very toxic to some varieties of apples.; use extreme caution when spraying near apples; do not use the same sprayer subsequently on apples.

% Use lime sulfur only during the dormant or late dormant period. Do not mix with oil.

For all products listed, read labels thoroughly for restrictions and warnings.

Bacteria

Crown Gall (Agrobacterium tumefaciens): There is only one bacterial disease which is a significant problem in the Northeast at present: crown gall. The disease is caused by the bacterium Agrobacterium tumefaciens. Since blueberries are grown on acidic soils, and the crown gall bacterium does not grow well in acidic soils, the disease occurs infrequently.

Globose, pea-size to large galls occur on low branches, twigs, and at the base of canes near the ground. Injured tissue is more likely to produce galls.

Management: Sanitation, purchasing healthy nursery plants and maintaining proper soil conditions are the most reliable controls.

Post-Harvest Diseases

As with most soft fruit, blueberries have particular post-harvest disease problems. There are three fungi which can cause major post-harvest losses: Colletotrichum acutatum (anthracnose), Botrytis cinerea (gray mold), and Alternaria spp. The diseases can cause up to 30% rot within 7 days of harvest even when refrigeration is used. Without refrigeration, berries can show 15% rot in 3 days.

Management: In New England, where virtually all highbush blueberries are sold fresh, well-ventilated containers and refrigeration should be combined with careful picking and handling.

Insects

Fruit Damaging Insects

Spotted Wing Drosophila (SWD) (Drosophila suzukii): SWD are invasive vinegar flies (fruit flies) that can attack unripen fruit. Female SWD cut into intact fruit with a serrated ovipositor to deposit eggs under the skin. This allows SWD larvae to be present during ripening, leading to a risk of detection in ripe fruit after harvest. During egg-laying and larval feeding, sour rot and fungal diseases can be introduced, further affecting fruit quality. There is a much greater risk of fruit contamination at harvest from SWD compared with native species that lay eggs only in already-damaged and rotting fruit.

Management: Monitoring for the annual arrival of SWD is particulatly important for blueberry. Pest pressure is often low for most of of the blueberry season and it is likely that early-ripening varieties may not need to be protected from SWD infestation. Homemade traps for the flies can be made by drilling 1/8” holes in plastic containers or cups (red or black color is most attractive). The cups should be baited with apple cider vinegar or sugar water with a pinch of yeast. Commercial traps (from Scentry or Trece) contain similar attractive odors as homemade recipes and may be more convienient. Check the traps regularly for flies. The males can be identified by a single small black spot near the top of each wing. The females have no spots. Once adult SWD are trapped and blueberries begin to turn blue, apply insecticides weekly through harvest, rotating between insecticide classes. Choose insecticides based on efficacy and preharvest interval. Good pruning is also an important part of SWD management as open canopies are less hospitable to egg-laying.

Winter Moth (Operophtera brumata): This is an important pest of blueberries and other deciduous plants, especially in Southeastern New England. Moths emerge from the soil in late November and may be active into January. Male moths are light brown to tan in color and attracted to lights at night. Females are gray, almost wingless and cannot fly, and may be found on tree trunks. After mating, females deposit tiny eggs in bark crevices or among lichens which overwinter. Eggs begin hatching in late March or early April after the first warm days of spring, generally around 20 Growing Degree Days (GDD) (base 50˚F) or about 200 GDD (base 40˚F). Egg hatch coincides with bud break of McIntosh apple trees. After hatching, larvae wriggle into swelling buds of blueberries and many deciduous tree, and begin feeding. Caterpillars continue feeding on leaves and flowers until late May when they drop to the ground to pupate. Destruction of flower buds can greatly reduce yield.

Winter moth larvae are pale green caterpillars with white longitudinal stripes running down both sides of the body. They are “loopers” or “inchworms” and have just 2 pairs of prolegs. Mature caterpillars are approximately one inch long.

Management: A dormant oil spray to trunks and branches of bushes may be helpful by killing overwintering eggs before hatching. However, some eggs are under bark flaps and loose lichen and may be protected from oil sprays. Caterpillars may also invade blueberries by blowing into plantings from nearby trees. Bacillus thuringiensis (B.t. kurstaki), manages winter moth caterpillars well once caterpillars are feeding on exposed foliage. B.t. and other insecticides are not effective when caterpillars are feeding inside closed buds. Spinosad is another biorational compound that works well against winter moth caterpillars. Finally, tebufenozide (e.g. Confirm) is an insect growth regulator (IGR) that works well on most lepidopteran caterpillars.

Blueberry Maggot (Rhagoletis mendax): The adult is a black fly about 1/5” long with a pattern of dark and clear bands on its wings. The maggots are white, legless, and about 1/4” long when full grown. Flies alight on fruit to lay eggs under the fruit skin just as fruit begins to turn blue. Maggots are later found in ripening and harvested fruit, making fruit unmarketable since berries become soft and mushy. Undetected infested berries contaminate pack-out.

Management: Red sticky spheres or yellow sticky rectangle traps (available from suppliers listed in appendix) can be used to monitor blueberry maggot populations in plantings. In large bushes, sticky traps should be hung in upper half of the canopy, suspended from wires and about 1-1/2 feet from outer foliage. All fruit and foliage within 8 inches of trap should be cleared away, and all traps positioned so that there is as much foliage and fruit surrounding them as possible. In small plantings, it may be possible to trap out this insect with a sufficient number of traps. Consult with your state’s regional fruit specialist for further information. Spray recommendations are found in the blueberry pest management schedule.

Brown Marmorated Stink bug (BMSB) (Halyomorpha halys): Adult BMSB are approximately 3/4 inch long and are shades of brown on both the upper and lower body surfaces. They are the typical “shield” shape of other stink bugs, almost as wide as they are long. To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings. Masses of 20-30 eggs are deposited on underside of leaves. The 5 nymphal stages range in size from 1/8 - 1/2 inch. Nymphs and adult BMSB feed on many hosts including small fruits, tree fruits, vegetables, ornamentals, and seeded crops such as corn and soybeans. BMSB feeds by puncturing fruit with piercing/sucking mouthparts. Fruit tissue dies at the point of entry and just below into the flesh, and the rest of the fruit grows around it. This leaves sunken areas on the skin and browning, dead tissue in the flesh.

BMSB has become a serious insect pest in mid-Atlantic states, southern New York, Connecticut, and possibly other New England states. It is unknown at this time whether there is one or two generations per year in New England.

Management: BMSB cannot be controlled with many common fruit insecticides, including Imidan and Sevin. Spray recommendations are found in the blueberry pest management schedule.

Plum Curculio (Conotrachelus nenuphar): This dark brown snout beetle is about 1/4” long with 4 humps on its wing covers. It feeds on developing flower buds and developing berries. Females lay eggs on the fruit, and after hatching, light colored larvae develop inside the fruit (one larva per fruit). Larval feeding causes fruit to ripen prematurely and drop off bushes.

Management: Plum curculio are more abundant where blueberries are located near fruit trees. Spray applications made at petal fall to manage cranberry or cherry fruitworm may also manage plum curculio.

Cranberry Fruitworm (Acrobasis vaccinii): Cranberry fruitworm larva (caterpillar) is green with some brownish-red coloration on its top surface, measuring 1/2” at maturity. It is found within developing and ripening berries. Feeding reduces yield and spoils marketability of berries. Eggs are laid in the calyx cup (blossom end) of unripe fruit. Hatched larvae move to the stem end of fruit, enter, and feed inside berries. Larvae consume 3-6 berries, filling berry skins with brown frass and tying berries together with silk.

Management: When damage is severe, treat the following year with insecticide. See pest management schedule for recommended materials. In small plantings, cranberry fruitworms may be managed by picking off infested berries, which are easily detected due to webbing and early ripening. Eliminating weeds around plants reduces overwintering protection for cocoons.

Cherry Fruitworm (Grapholita packardi): At maturity, cherry fruitworm larvae are orange-red and about 1/4-1/2” long and found within developing and ripening berries. Feeding reduces yield and spoils marketability of berries. Soon after petal fall, hatching larvae bore into the calyx cup (blossom end) of berries, feed until about half-grown, and then move to a second fruit. (This is distinct from the cranberry fruitworm described above.) The two infested berries are usually joined by silk.

Management: When damage is severe, treat the following year with insecticide. See pest management schedule for recommended materials.

Leaf/Shoot Damaging Insects

Gypsy Moth (Lymantria dispar dispar): Young gypsy moth larvae (caterpillars) are hairy, dark brown to black in color and older caterpillars are marked with red and blue spots. They range in size, from 1/4 to 2” in length, depending on age. In outbreak years, larvae feed on leaves and buds, causing complete or partial defoliation and fruit loss.

Management: Remove egg masses present in plantings by early April. Small caterpillars can blow in from surrounding, infested trees in early May.  Bt insecticides effectively manage small, young caterpillars, but other insecticides are needed to manage large larvae. See pest management section for insecticide recommendations.

Blueberry Blossom Weevil; Cranberry Weevil (Anthonomus musculus): This is a dark reddish brown snout beetle, 1/8” long, with a curved snout. It emerges in spring, feeds and lays eggs in expanding flower and leaf buds. Weevils hide between clustered buds, and small infestations may be difficult to find. Damage results when punctured flowers do not open. Damaged leaf buds produce an abnormal cluster of dwarfed leaves. Adults of the second generation sometimes feed on blueberry leaves.

Management: No insecticides are labeled for this pest. Disking between rows and raking/hoeing under plants is helpful. Eradication of wild blueberries or other ericaceous plants in the vicinity of the blueberry planting may be beneficial.

Scale Insects; Putnum Scale and Lecanium Scale (Aspidiotus ancylus and Lecanium nigrofasciatum): These insects appear mound-shaped, of varied colors, and usually measuring 1/8” or less in length. They are found on rough, loose bark of older stems and sometimes on fruit. Infestations can result in reduced vigor and yield of bushes by feeding on plant sap. Fruit lecanium scale eggs hatch in early July (late June in southernmost New England) and first generation putnam scale crawlers emerge in early June.

Management: Good pruning is the first step in controlling scale insects. Prune out weakened canes. During dormancy, apply superior-type oil of 60- or 70-second viscosity at 3 gallons per 100 gallons of water. To avoid injury, apply when there is no danger of freezing temperatures for at least 24 hours after treatment.  See Insecticide Efficacy and Pest Management Tables in this chapter for other recommended materials and timing.

Blueberry Tip Borer (Hendecaneura shawiana): In June, before new growth has begun to harden, some blueberry shoots may begin to wilt, arch over, and become discolored, the leaves turning yellowish with red veins and stems turning purplish. This injury, which may be mistaken for primary mummyberry infection, is caused by blueberry tip borer. Newly hatched caterpillar, tiny and pink, enters soft stem and bores channels that may extend for 8 or 10” by autumn and result in the destruction of the stem’s fruit-production potential the following year.

Management: Prune out damaged tips when found and burn infected canes. A standard spray program used for other insect pests normally keeps this pest under control.

Blueberry Bud Mite (Acalitus vaccinii): Blueberry bud mites are whitish in color and tiny. Unlike other mites, they are elongate and conical, with 4 legs bunched near the head at the broad end of the mite. Heavily infested buds have a definite reddish coloration and characteristic rough bumps on outer bud scales. Eggs,  immatures, and adult mites are present throughout the year, generally confined to buds and blossoms. During fall and winter, many mites may be found between scales of a single fruit bud.

Bud mites feed on the surface of bud tissues and bud scales. Injured buds desiccate and usually produce distorted flowers. These flowers may fail to set fruit, or develop into fruit with rough skins. The potential for damage differs with variety.

Management: Plants should be inspected for bud mites in September, before new buds are well formed. Look for them under bud scales and between bud parts. Economic threshold levels have not been determined for bud mites. Thorough pruning of infested canes provides good control of bud mites. Limited chemical control measures are available. A new miticide, Magister SC, is registered for blueberry bud mite management and may be applied once per year after petal fall.

Blueberry Stem Gall Wasp (Hemadas nubilipennis): The adult blueberry stem gall wasp is a small (less than 1/8”) shiny black insect with delicate wings. It lays eggs in succulent shoots. Several grub-like larvae develop together inside the shoot, stimulating the shoot to grow abnormally and resulting in a pithy, kidney-shaped gall 3/4 to 1-1/4” long. Pupation occurs within larval chambers and new adults emerge from the galls during bloom, leaving exit holes. Early in the season galls are greenish and spongy to the touch. By fall the galls turn brownish-red and become hard. Shoot growth is reduced and the shoot may be diverted at severe angles.

Blueberry stem gall wasp can cause severe reduction in shoot growth and stem vigor. Hundreds of galls can develop on a single bush, reducing fruit production. Susceptibility to galls may depend on variety. This insect is rarely encountered in fields managed with standard chemical pesticide programs, but it can be a major pest of organically managed fields.

Management: Chemical treatments directed toward other pests are generally sufficient to keep stem gall in check. Removal and destruction of gall during normal pruning operations will also help manage this pest.

White Grubs - Japanese Beetle (Popillia japonica), Rose Chafer (Macrodactylus subspinosus), Asiatic Garden Beetle (Maladera castanea), and others: White grubs are the larvae of a variety of beetle species some of which are listed above. White grub larvae are generally white or cream colored with brown heads and legs, and hold their bodies in a distinct hooked or C-shape. Stretched out, larger species may be over one inch in length. Many white grub species can be identified by distinctive patterns of stiff hairs located at the underside of abdomen tip. Most species overwinter as grubs deep in the soil and pupate in late spring before emerging as adult beetles. Some species feed on roots of plants for more than one year before completing development. Time of pupation and adult emergence varies with species.

Adults of white grubs are known generically as May Beetles, June bugs, chafers, or scarab beetles. The adults of some species feed on foliage, flowers and fruits of many plants. Japanese beetle and rose chafer adults can be significant pests of blueberry during harvest when they contaminate berries.

Recently white grubs have become serious pests in some fields, with populations as high as 30 grubs per bush. Grubs consume feeder roots and may also girdle or clip off larger roots. Infested plants may not show any outward signs of injury until a period of drought stress, when the reduced root system cannot provide enough water to the plant. Damaged bushes show low vigor and reduced production. Adults, especially Japanese beetle and rose chafer, sometimes become serious pests by consuming leaves and scarring berries.

Management: Unfortunately, sampling for white grubs damages roots of blueberry bushes. Growers should check new sites for white grubs before establishing a field, and take actions against grubs before planting. Admire Pro can be applied to soil to control white grubs. When applied correctly, it suppresses Asiatic garden beetle larvae and is effective against all other species of white grubs. There is great interest in the use of pathogenic nematodes as biological control agents for grubs. Adults are generally easy to control with foliar sprays, but timing is difficult since these are highly mobile insects that may suddenly appear in the field. Surround is a kaolin clay-based product that can deter adults from feeding on foliage. It may be of interest to organic growers, though removing Surround from fruit is difficult.

Yellow-necked Caterpillar (Dantana ministra): These hairy yellow caterpillars are usually found in large groups in mid- or late summer. If unnoticed, they can entirely strip foliage from a bush.

Management: Caterpillar strains of Bacillus thuringiensis (Bt) products are effective in managing larvae, especially when they are small. Chemical insecticides are also effective. Spraying the entire planting is not required.

Sharp-nosed leafhopper (Scaphytopius acutus): SNLH feeds and reproduce on blueberry, huckleberry, cranberry, and other related plants. SNLH feeding causes little direct damage but it transmits the phytoplasma that causes stunt disease in blueberries. They are small brown insects with a pointed head. SNLH picks up the disease while feeding on infested bushes and carries it to other plants in subsequent feedings. Usually only adults carry the disease from plant to plant, since nymphs are wingless and can’t fly. Adults are abundant in the woods and may move to commercial blueberry fields in the spring. Eggs overwinter inside fallen leaves and hatch in mid-May. Nymphs from the first generation reach adult stage in mid-June, while nymphs from the second generation reach adulthood in early August. Adults move back to the woods in the fall.

Management: First generation SNLH is often controlled with sprays targeted for plum curculio, aphids, and cranberry fruitworm. Treatment decisions for the 2nd generation should be based on individual population levels, as well as any history of stunt disease on your farm. Because adults migrate from woods, monitoring should concentrate on field perimeter. Insecticides are usually applied just prior to peak flight, generally late August to early September. It is also important to remove all plants that show symptoms of stunt disease. Removal of bushes should be done after insecticide treatment to avoid movement of leafhoppers from infested to healthy plants.

Blueberry aphid (Illinoia pepperi) is the vector of blueberry shoestring virus which can cause bush decline and significant yield reductions. It is also a potential vector of blueberry scorch virus. Because of the ability of aphids to serve as vectors of plant disease, they should be controlled to minimize virus spread in infected fields and in susceptible fields near to virus-infected fields.

Management: Blueberry aphids are most often found on the undersides of young leaves at the base of plants. Insecticides can be applied in June as aphid populations start to increase. Spray should be directed at base of plants and good coverage is essential for effective aphid control. This will be more challenging in weedy fields. See table 33 for insecticides effective against aphids.

Table 34. Insecticides registered for use on blueberries and their primary uses.
Insecticide IRACa GROUP ACTIVE INGREDIENT aphid

blueberry 

maggot

brown

marmorated

stink bug

bud

mite

cranberry

weevil

cranberry/

cherry

fruit worm

japanese beetle leafhopper leaf roller plum curculio scale spotted wing drosophila thrips white grub
Actara 4A thiamethoxam +++ + -- 0 +++ 0 ++ +++ -- + -- -- 0 --
Admire Pro 4A imidacloprid +++ ++ ++ 0 -- 0 ++ ++ -- -- -- + 0 +++
Agree 11 Bacillus thuringiensis ssp aizawai 0 0 0 0 0 -- 0 0 ++ 0 0 0 0 0
Altacor 28 chlorantraniliprole -- -- -- 0 -- ++ ++ -- ++ -- -- -- -- ++
*Asana 3 esfenvalerate ++ ++ -- 0 +++ ++ ++ ++ +++ ++ -- +++ -- --
Assail 4A acetamiprid +++ +++ -- -- -- + ++ ++ -- 0 -- +++ ++ --
Avaunt 22A indoxacarb -- -- -- -- -- ++ -- -- -- ++ -- -- -- --
Aza-Direct UN azadirachtin -- + -- -- -- -- + -- -- -- -- 0 -- --
Azera 3,UN pyrethrins, azadirachtin + + -- -- -- -- + -- -- -- -- + -- --
Biobit 11 Bacillus thuringiensis, ssp kurstaki 0 0 0 0 0 -- 0 0 ++ 0 0 0 0 0
*Bifenture 3 bifenthrin +++ -- ++ -- -- -- -- ++ +++ -- -- ++ -- --
*Brigade 3 bifenthrin +++ ++ ++ -- -- -- +++ ++ -- -- -- ++ -- --
Confirm 18 tebufenozid -- -- -- -- -- ++ 0 -- ++ -- -- -- -- --
Cormoran 4A,15 acetamiprid, novaluron +++ ++ -- -- -- -- -- -- ++ -- -- +++ -- --
*Danitol 3 fenpropathrin ++ ++ ++ ++ -- +++ +++ ++ +++ ++ -- ++ -- --
Delegate 5 spinetoram -- ++ -- -- -- +++ -- 0 +++ + -- +++ ++ --
Deliver 11 Bacillus thuringiensis, ssp kurstaki 0 0 0 0 0 -- 0 0 ++ 0 0 0 0 0
Des-X   potassium salts of fatty acids ++ -- -- -- -- -- -- + -- -- -- -- -- --
*Diazinon 1B diazinon ++ ++ -- 0 ++ ++ 0 +++ ++ +++ +++ +++ ++ +
Dipel 11 Bacillus thuringiensis, ssp kurstaki 0 0 0 0 0 ++ 0 0 ++ 0 0 0 0 0
Entrust 5 spinosad -- ++ -- 0 -- +++ 0 +++ +++ 0 0 ++ ++ --
Esteem 7C pyriproxyfen ++ -- -- -- -- ++ 0 + ++ -- +++ + -- --
Exirel 28 cyantraniliprole ++ ++ -- ++ -- +++ ++ -- +++ ++ -- +++ -- --
GF-120 Naturalyte Bait 5 spinosad -- ++ -- 0 -- ++ 0 -- ++ 0 0 ++ ++ --
Grandevo UN Chromobacterium
subtsugae
+++ -- -- -- -- ++ -- -- +++ -- -- ++ -- --
* Hero 3 zeta-cypermethrin,
bifenthrin
+++ ++ ++ -- -- ++ ++ ++ ++ ++ -- ++ -- --
Imidan 1B phosmet -- +++ -- -- +++ +++ ++ +++ +++ +++ ++ +++ 0 --
Intrepid 18 methoxyfenozid -- -- -- -- -- +++ -- -- +++ -- -- -- -- --
JMS Stylet Oil   mineral oil ++ 0 -- ++ -- -- 0 -- -- -- +++ -- -- --
*Lannate 1A methomyl ++ ++ ++ -- ++ +++ + ++ ++ + -- +++ + --
Magister SC 21A fenazaquin -- -- -- +++ -- -- -- -- -- -- -- -- -- --
Malathion 1B malathion + ++c ++ -- + + + + -- ++ -- ++ ++ --
Molt-X UN azadirachtin + + -- -- -- -- + -- -- -- -- 0 -- --
Movento 23 spirotetramat +++ -- -- -- -- -- -- -- -- -- -- -- -- --
M-Pede   Potassium salts
of fatty acids
++ -- -- -- -- -- -- + -- -- -- -- -- --
*Mustang Maxx 3 zeta-cypermethrin -- + ++ -- -- ++ ++ ++ ++ ++ -- +++ -- --
Neemix UN azadirachtin ++ + -- -- -- -- + -- ++ -- -- 0 -- --
NemaShield HB N/A Heterorhabditis bacteriophora -- -- -- -- -- -- + -- -- -- -- -- -- +
Platinum 4A thiamethoxam +++ -- -- 0 -- 0 -- ++ -- + -- -- 0 +++
Pyganic 3 pyrethrin + + -- -- -- -- + -- -- -- -- + -- --
Pyrenone 3 pyrethrin +PBO + + -- -- -- -- + -- -- -- -- + -- --
Rimon 15 novaluron -- -- -- -- -- ++/+++ -- -- +++ ++ -- ++ -- --
Senstar 23,7C spirotetramat,
pyriproxyfen
++ -- -- -- -- -- -- -- -- -- -- -- ++ --
Sevin 1A carbaryl -- + -- -- + + ++ ++ ++ ++ --- ++ -- --
Sivanto Prime 4D flupyradifurone +++ ++ -- -- -- -- -- -- -- -- +++ -- ++ --
SuffOil-X   mineral oil ++ 0 -- ++ -- -- 0 -- -- -- +++ -- -- --
Superior Oil   mineral oil ++ 0 -- ++ -- -- 0 -- -- -- +++ -- -- --
Surround   kaolin clay -- + ++ -- -- -- + -- -- ++ -- -- -- --
Tersus 3 pyrethrins + + -- -- -- -- + -- -- -- -- + -- --
Trilogy   neem oil -- + -- -- -- -- + -- -- -- -- 0 -- --
Venerate UN Burkholderia spp. +++ -- -- -- -- +++ -- -- +++ -- -- -- -- --
Verdepryn 28 cyclaniliprole -- -- -- -- -- ++ -- -- ++ -- -- -- -- ++
 XenTari 11 Bacillus thuringiensis, ssp aizawai 0 0 0 0 0 -- 0 0 ++ 0 0 0 0 0

0=not effective, +=poor, ++=good, +++=excellent, --=insufficient data

Products with the same IRAC group number act by the same mode of action. Repeated use of the same mode of action should be avoided, in order to avoid reductions in pesticide efficacy via development of chemical resistance in the pest population. For more on information on managing pesticide resistance, go to www.irac-online.org.

*Restricted use material; pesticide applicators license required.      OMRI listed - organic production; go to www.omri.org for details.

Always read the label for important restrictions or warnings about tank mix compatibility or phytotoxicity warnings.

Table 35. Highbush Blueberry Pest Management Table

Table 35. Highbush blueberry pest management table†.

For resistance management do not make more than 2 sequential applications of fungicides in the same FRAC group or insecticides in the same IRAC group. See product labels or RAC GROUP column in this table for groups.
Pest

RAC
Group

Spray Material, Rate/A
(pre harvest interval PHI)
Cultural Practices and
Scouting Notes
Comments
Dormant and Delayed Dormant
Scale insects  
 
Superior oil, 2-2.5% (0) Or
JMS Stylet Oil, 3-6 qt/100 (0)
SuffOil-X, 1-2% (0)
Prune out old, weakened canes.
 
Apply oil during dormancy using 250-300 gallons of spray (300-400 psi) per acre to ensure thorough coverage and when no danger of freezing temperatures within 24 hours.
Winter moth
IRAC

 

 
18
5
7C
5
1B

Superior oil, 2-2.5% (0) Or
JMS Stylet Oil, 3-6 qt/100 (0)
plus one of the following:

Confirm 2F, 16 oz (14)
Delegate WG, 3-6 oz (3)
Esteem 35WP, 5 oz (7)
Entrust, 1.25-2 oz (3)
Imidan 70W, 1 1/3 lb (3)

  Where winter moths are numerous, insecticide should be applied when eggs are hatching. If population not at outbreak levels (not defoliating trees) but still present, apply insecticide after caterpillars observed but before bloom.
Mummyberry
 
 
Bury over-wintering mummies by cultivation or applying 3-4" mulch before mushroom cups (apothecia) appear.
'Burlington', 'Collins', 'Jersey', 'Darrow', 'Rubel', and 'Bluetta' appear somewhat resistant; 'Earliblue' and 'Blueray' appear more susceptible to mummyberry.
Fusicoccom canker
Phomopsis twig blight
FRAC
M01
M01
M01
M01
M01
M02
3
M03
 
 
Badge SC, 2-4 pts (0)
Badge X2, 1-2.25 lb (0)
Cuprofix Ultra, 2-4 lb (0)
Kocide 2000/Kocide 2000-O, 2-4 lb (0)
Kocide 3000/Kocide 3000-O/Kocide, 1.0-2.25 lb (0)
Miller Lime Sulfur, 5-6 gal (0)
Quash, 2.5 oz (7)
Ziram 76DF, 1.5 lb (21)
 
Prune out and destroy affected canes.
'Weymouth', 'Berkeley', and 'Earliblue' are very susceptible to Fusicoccum.
Use Lime Sulfur only once in Spring. May be used again in autumn where Phomopsis is a problem.
Do not use Lime Sulfur within 14 days of an oil spray or when temperatures are above 75˚F.
Avoid practices such as late season fertilization that makes bushes more vulnerable to winter injury. Winter-injured bushes are more susceptible to Phomopsis and Fusicoccum infections.
Phytophthora root rot
FRAC
P07
P07
P07
P07
4
 
 
 
 

BM02
 
Aliette WDG, 5 lb (0.5)
pHorcePhite, 2-4 qt (0)
Phostrol, 2.5-5 pt (0)
ProPhyt, 4 pt (0)
Ridomil Gold SL (45)
New Plantings, 3.6 pt broadcast
at or before time of planting
(repeat once)
Established Plantings, 1/4 pt/1000 ft
of row, (repeat once)
RootShield Plus WP (0)
  • Do not plant blueberries on wet soils.
  • If wet site is unavoidable, install drainage tile and plant blueberries on raised beds.
  • Phytophthora damage symptoms may mimic nutritional deficiency symptoms.
Ridomil Gold: Apply only as an emergency use, not as a routine or preventative treatment.
Apply in spring before growth begins in established plantings. In new plantings, apply at or just after planting.
In new plantings, do not exceed 3.6 gallons/A within 12 months of harvest or illegal residues may result.
Aliette: Apply as a 5 ft. band. Do not tank mix Aliette with copper compounds or apply to foliage with copper residues or phytotoxicity may occur.
Phostrol: Begin foliar sprays at pink bud stage, and continue on a 14-21 day interval.
RootShield: In furrow spray or transplant starter: 16-32 oz/acre. Cutting or barerooted transplant dip:  6 oz/20 gal water
Bud-break (aka Bud Swell, Green tip) through pre-bloom
Gypsy moth
Winter moth
IRAC
11
3, UN
18
11
11
UN
3
18
 
UN
UN
11
Insecticides listed at dormant plus:
Agree WG, 0.5-2 lb (0)
Azera, 1-3.5 pt (0)
Confirm 2F, 16 oz (14)
Deliver, 0.25 - 1.5 lb (0)
Dipel DF, 0.5-2 lb (0)
Grandevo DF, 1-3 lb (0)
*Hero, 4-10.3 oz (1)
Intrepid 2F, 16 oz (7)
Molt-X, 8-10 oz (0)
Venerate XC, 1-8 qt (0)
XenTari, 0.5-2 lb (0)
 
Confirm and Intrepid are most effective against young larval stages.

Use Grandevo when pest populations are low and/or in young growth stage.
Blueberry blossom weevil,
Cranberry weevil
IRAC
3
28
 
*Asana XL, 4.8-9.6oz (14)
Verdepryn 100SL, 8.2-11 fl. oz. (1)
Disking between rows and raking/hoeing under plants helpful.
Eradication of wild blueberries in the vicinity of the blueberry planting is advised.
Mummy berry
FRAC
BM02
11
M5
BM02
M4
M4
17, M4
BM02
BM02
3
BM02
7,9
29
M05
3
19
7, 11
3
3
3
3, 11
P05
BM02
9,12
 
Actinovate AG, 3-12 oz (0)
Abound F, 6.0-15.5 oz (0)
Bravo Ultrex, 2.7-3.6 lb (42)
BotryStop, 3 lb (0)
Captan 80 WDG, 1.25-3.1 lb (0)
Captec 4L, 0.75-1 qt (0)
Captevate 68 WDG, 4.7 lb (0)
Double Nickel 55, 0.25-3 lb (0)
Double Nickel LC, 0.5-6 qt (0)
Indar 75 WSP, 2 oz (30)
LifeGard, 4.5 oz/100 gal (0)
Luna Tranquility, 13.6-27 oz (0)
Omega 500F, 1.25 pts (30)
Oranil 6L, 3-4 pt (42)
Orbit, Tilt, 6 oz (30)
Oso 5% SC, 6.5% (0)
Pristine, 18.5-23 oz (0)
Proline 480 SC, 5.7 oz (7)
PropiMax EC, 6 oz (30)
Quash, 2.5 oz (7)
Quilt Xcel, 14-21 fl oz (30)
Regalia, 1-4 qt (0)
Serenade Max, 1-3 lb (0)
Switch, 11-14 oz (0)
Before mummy cups appear (mid-March), disk between rows and rake, sweep, and hoe under plants or cover with 3-4” of mulch.
As first mummy cups appear, apply 200 lbs of 50% Urea prills.
Cultivation and Urea are most effective when both are used.
Abound should be used with extreme caution to avoid phytotoxicity to apples. See label for further information.
Use of propiconazole for mummy berry control has been associated with an increase in Botrytis severity.
 
Tank mix Regalia with other registered fungicides.
 
Double Nickel and Oranil for mummy berry suppression only.
 
Be aware of pre-harvest interval restrictions for Omega and Oranil.

Do not use a silicone surfactant or penetrant adjuvant with BotryStop.
 
 
Early to mid-bloom
Gypsy moth
Winter moth
IRAC
11
11
11
11

Agree WG, .5-2 lb (0)
Deliver, 0.25 - 1.5 lb (0)
Dipel DF, 0.5-2 lb (0)
XenTari, 0.5-2 lb (0)
   
Mummy berry
 
Same as bud-break through pre-bloom
Scout field for mummyberry strikes to determine risk level for secondary infections.
Fungicide applications are especially important following frost/freeze events during bloom.
Botrytis blossom and twig blight
FRAC
BM02
BM02
M4 
17, M4
BM02
BM02
BM02
7,9
UN
3
BM02
M03


Actinovate AG, 3-12 oz (0)
BotryStop, 3 lb (0)
Captan 50WP, 5 lb (0)
CaptEvate 68WDG, 3.5-4.7 lb (0)
Double Nickel 55, 0.25-3 lb (0)
Double Nickel LC, 0.5-6 qt (0)
LifeGard LC, 4.5 oz/100 (0)
Luna Tranquility, 16-27 oz (0)
Oxidate, 40-128 oz (0)
Quash, 2.5 oz (7)
Serenade Max, 1-3 lb (0)
Ziram 76DF, 3 lb (21)

Avoid high rates of nitrogen fertilizer which tends to promote growth that is more susceptible to infection. Do not use a silicone surfactant or penetrant adjuvant with BotryStop.
Anthracnose
Phomopsis twig blight
FRAC
UN
M4
17, M4
M01
BM02
BM02
17
BM02
29
M5
19
P07
7, 11
3
3
3, 11
NC
BM02
9, 12
M03
 
 
Actinovate AG, 3-12 oz (0)
Captan 50WP, 5 lb (0)
Captevate 68 WDG, 3.5-4.7 lb (0)
Cueva, 0.5-2 gal (0)
Double Nickel 55, 0.25-3 lb (0)
Double Nickel LC, 0.5-6 qt (0)
Elevate 50WDG, 1.5 lb (0)
LifeGard, 4.5 oz/100 (0)
Omega 500F, 1.25 pt (30)
Oranil 6L, 3-4 pt (42)
Oso 5% SC, 6.5 oz (0)
pHorcepHite, 2-4 qt (0)
Pristine WG, 18.5-23 oz (0)
Proline 480 SC, 5.7 oz (7)
Quash, 2.5 oz (7)
Quilt Xcel, 14-21 fl oz (30)
Rendition, 48 oz (0)
Serenade Max, 1-3 lb (0)
Switch, 11-14 oz (0)
Ziram 76DF, 3 lb (21)
 
Many mummy berry materials also labeled for these diseases.
Use Captevate at the highest rate (4.7 lb) for anthracnose. Captevate NOT labeled for Phomopsis.
Be aware of pre-harvest interval restrictions for Omega and Oranil.
Apply Cueva at start of flowering and every 7-10 days through bloom. Do not reapply within 7 days.
Rendition is hydrogen peroxide plus peroxyacetic acid. Apply during bloom when weather conditions favor disease development.
Blueberry leaf rust
FRAC
NC
M5
3
3
3
3
NC
 
JMS Stylet Oil, 3-6 qt/100 (0)
Oranil 6L, 3-4 pt (post harvest)
Orbit, Tilt, 6 oz (30)
Proline 480 SC, 5.7 oz (7)
PropiMax EC, 6 oz (30)
Quash, 2.5 oz (7)
SuffOil-X, 1-2% (0)
Remove alternate host (Hemlock) from within 1/4 mile if possible, especially those upwind of blueberry planting.
 
Plant resistant cultivars such as 'Bluecrop', 'Burlington', 'Collins', 'Dixi', 'Earliblue', 'Ivanhoe', 'Stanley', or 'Weymouth' if possible.
 
Oranil can be used after harvest to maintain healthy foliage.
Powdery mildew
FRAC
BM02
3
NC
M02
7,9
M02
BM02
3
NC
3
3
NC
18B
 
Actinovate AG, 3-12 oz (0)
Indar 75 WSP, 2 oz (30)
JMS Stylet Oil, 3 qts (0)
Kumulus DF, 6-15 lb (0)
Luna Tranquility, 13.6-27 oz (0)
Microthiol Disperss, 6-15 lb (0)
Milstop SP 2.5-5 lb (0)
Orbit, Tilt, 6 oz (30)
Oxidate, 40-128 oz (0)
PropiMax EC, 6 oz (30)
Quash, 2.5 oz (7)
SuffOil-X, 1-2% (0)
Trilogy, 1-2% sol (0)
Prune for good drying conditions.
Plant resistant cultivars when possible.
Do not use sulfur products and oil products within 2 weeks of each other.
Petal Fall (remove honey bees before spraying)
Cranberry fruitworm
Cherry fruitworm
IRAC
11
28
3
4A
22A
11
3
18
3
5
11
11
5
7C
28
UN
3,4A
1B
18
1A
1B
UN
3
15
1A
UN
11
28
 
Agree WG, .5-2 lb (0)
Altacor, 3.0-4.5 oz (1)
*Asana XL, 4.8-9.6 0z (14)
Assail 30 SG, 4.5-5.3 oz (1)
Avaunt, 3.5-6 oz, (7)
Biobit 1.6 FC, 1-2 pt (0)
*Brigade WSB, 5.3-16 oz (1)
Confirm 2F, 16 oz (14)
*Danitol 2.4E, 10.6 (3)
Delegate WG, 3-6 oz (3)
Deliver, 0.25-1.5 lbs (0)
DiPel DF, 1-2 lb (0)
Entrust, 1.25-2 oz (3)
Esteem 0.86EC, 16 oz (7)
Exirel, 10-13.5 fl oz (3)
Grandevo, 1-3 lb (0)
*Hero, 40-10.3 oz (1)
Imidan 70W, 1 1/3 lb (3)
Intrepid 2F, 10-16 oz (?)
*Lannate 90, 0.5 - 1 lb (3)
Malathion 5E, 1.5 pt (1)
Molt-X, 8 oz (0)
Pyrenone 0.5EC, 2-12 oz (0)
Rimon 0.83EC, 20 oz (8)
Sevin XLR, 1.5-2 qts (7)
Venerate XC,1-8 qt (0)
Verdepryn 100SL, 8.2-11 fl. oz. (1)
XenTari, .5-2 lb (0)
Disking between rows and raking and hoeing under plants is helpful for fruitworm management.
In small plantings remove and destroy infested fruit (which can be identified because it turns prematurely blue)
Fruitworms are active for about five weeks and they cannot be controlled with only one post-pollination spray.
Agree, Biobit and DiPel are bacterial biological insecticides containing Bacillus thuringiensis and must be ingested to be effective. Apply when newly hatched larvae (1st or 2nd instar) begin feeding. Larvae cease feeding in hours and die in 2-5 days.
White grubs
IRAC
4A
 N/A
 
 
Admire Pro, 7-14 oz soil (7)
NemaShield HB, 1 billion nematodes (0)
 
Apply Admire Pro through low pressure irrigation or as a band treatment followed by rainfall or irrigation. Do not exceed 0.5 lb active ingredient per acre per year. The most effective timing is between June 1 and July 15.
 
When applying nematodes, water after application and keep soil moist two weeks after application.  
 
   
 
 
Aphid
IRAC
4A
3
4A
3, UN
3
15,4A
UN
28
UN
3,4A
3
23

3
4A
23,7C
4D
UN
 
UN
 
Actara, 3-4 oz (3)
*Asana XL, 4.8-9.6 oz (14)
Assail 30SG, 2.5-5.3 oz (1)
Azera, 1-3.5 pt (0)
*Brigade WSB, 5.3-16 oz (1)
Cormoran, 9-12 oz (8)
Des-X, 2% sol. (0)
Exirel, 13.5-20.5 fl oz (3)
Grandevo DF, 1-3 lb (0)
*Hero, 4-10.3 oz (1)
Molt-X, 8-10 oz (0)
Movento 2SC, 8-10 oz (7)
M-Pede, 1-2% sol. (0)
Neemix, .25-1 pt (0)
Platinum, 5-12 fl oz (75)
Senstar, 16-20 fl oz (7)
Sivanto Prime 200SL, 7-10.5 fl oz (3)
 SuffOil-X, 1-2% (0)
Trilogy, 1-2% sol (0)
Venerate XC, 2-4 qt (0)
 
Aphids can vector the phytoplasma that causes Blueberry Scorch disease and so should be controlled in blueberry plantings.
Mix penetrating adjuvant with Movento.
 
Venerate for aphid suppression only.
Anthracnose
 
Same as early-mid bloom
 
 
Powdery mildew
 
Same as early-mid bloom
 
 
First cover (about 10 days after Petal Fall; some berries begin to color)
Cranberry fruitworm
Cherry fruitworm
 
Same as petal fall
 
Apply 7 to 12 days after petal fall
Blueberry maggot
IRAC
3
4A
UN
3
15,4A
3
5
28
5
UN
3,4A
1B
1A
1B
UN
23
3A
15
1A
4D
 
3
28
 
*Asana XL, 9.6 oz (14)
Assail 30 SG, 4.5-5.3 oz (1)
Aza-Direct, 1-3.5 pts (0)
*Brigade WSB, 5.3-16 oz (1)
Cormoran, 12 oz (1)
*Danitol 2.4EC, 10.6 oz (3)
Delegate 25WG, 3-6 oz (3)
Exirel, 13.5-20.5 oz (3)
GF-120 Naturalyte Bait, 10-20oz (1)
Grandevo WDG, 2-3 lb (0)
*Hero 4-10.3 oz (1)
Imidan 70 W, 1 1/3 lb (3)
*Lannate SP, 0.25-0.5 lb (3)
Malathion 5EC, 1 pt (1)
Molt-X, 8-10 oz (0)
Movento, 10 oz (7)
Pyrenone 0.5EC, 2-12 oz (0)
Rimon 0.83EC, 20-30 of (8)
Sevin 4F, 1.5-2 pt (7)
Sivanto Prime, 12-14 fl oz (3)
Surround WP, 12.5-50 lb (0)
Tersus, 4.5-17 fl (0)
Verdepryn 100SL, 8.2-11 fl. oz. (1)
Use sticky traps (red/green spheres or yellow rectangles; See source listing in appendix) to monitor population and activity.
Apply insecticide 7-10 days after first trap catch.
Check traps twice each week.
Apply sprays when berries begin to turn blue or when flies begin to lay eggs, usually late June. Repeat every 10 days through harvest.
Be aware of pre-harvest intervals and other restrictions with repeated sprays.
Malathion should be used with 1.5 qt Staley’s Sauce Base No. 7 (NuLure).
 
Mix penetrating adjuvant with Movento.
 
Delegate for blueberry maggot suppression.
 
GF-120 Naturalyte Bait contains sugar as an insect attractant, in order to increase efficacy of the active ingredient.
Brown marmorated stink bug
(BMSB)
IRAC
4A
3, UN
3
3
3
3,4A
1A
1B
3
UN
 
Admire Pro, 2.1-2.8 oz (3)
Azera, 1-3.5 pt (0)
*Bifenture 10DF, 5.3-16.0 oz (1)
*Brigade WSB, 5.3-16.0 oz (1)
*Danitol 2.4EC, 10.6 oz (3)
*Hero, 4-10.3 oz (1)
*Lannate 90, 0.5 - 1 lb (3)
Malathion 5E, 2.5-3 pt (1)
*Mustang Max 4.0 oz (1)
Surround WP, 12.5-50 lb (0)
 
As of 2020, brown marmorated stink bugs have been found in all New England states but have not been reported as a problem in blueberry production.
Aphids
 
Same as petal fall
 
 
Anthracnose
 
Same as petal fall
 
 
Powdery mildew
 
Same as petal fall
 
 
Spotted wing Drosophila
(SWD)
IRAC
4A
3
3
3
15,4A
3
5
5
28
UN
3
1B
1A
3
3A
15
28
 
Assail 30 SG 4.0-6.9 oz (1)
*Asana XL, 4.8-9.6 0z (14)
*Bifenture 10DF, 5.3-16.0 oz (1)
*Brigade WSB, 5.3-16.0 oz (1)
Cormoran, 20 oz (8)
*Danitol 2.4EC, 10.6 oz (3)
Delegate WG, 6 oz (3)
Entrust, 4-6 oz (3)
Exirel, 13.5-20.5 (3)
Grandevo DF, 2-3 lb (0)
*Hero, 4-10.3 oz (1)
Imidan 70 W, 1 1/3 lb (3)
*Lannate 90, 0.5 - 1 lb (3)
*Mustang Max, 4.0 oz (1)
  Pyganic 1.4EC, 32-64 oz (0)
Rimon 0.83EC, 20-30 oz (8)
Verdepryn 100SL, 8.2-11 fl. oz. (1)
Use traps baited with apple cider vinegar plus ethanol alcohol (90% apple cider vinegar plus 10% ethanol) and/or fermenting yeast to monitor population.
Spray once SWD adults are captured and fruit begins to turn color.
 
Grandevo for SWD suppression only.
 
When using Rimon, tank mix with an adulticide to control adult SWD
Second and additional covers (10 days from previous cover, repeat as needed)
Blueberry maggot   Same as first cover above See comments above for Blueberry maggot
Brown marmorated stink bug   Same as first cover above  
Japanese beetle and other scarab beetles
IRAC
4A
4A
28
3
4A
UN
3A
3
28
3
1B
UN
N/A
4A
3A
1A
 
3
28
 
Actara, 3-4 oz (3)
Admire Pro, 2.1-2.8 oz (3)
Altacor, 4.5 oz (1)
*Asana XL, 4.8-9.6 oz (14)
Assail 30 SG, 4.5-5.3 oz (1)
Aza-Direct, 1-3.5 pts (0)
*Brigade 2EC, 2.1-6.4 (1)
*Danitol 2.4EC, 10.6 oz (3)
Exirel, 13.5-20.5 (3)
*Hero, 4-10.3 oz (1)
Imidan 70W, 1.3 lbs (3)
Molt-X, 8-10 oz (0)
NemaShield HB, 1 billion nematodes (0)
Platinum, 5-12 oz (75)
Pyrenone 0.5EC, 2-12 oz (0)
Sevin XLR Plus, 1-2 qt (7)
Surround WP, 12.5-50 lb (0)
Tersus, 4.5-17 fl (0)
Verdepryn 100SL, 8.2-11 fl. oz. (1)
Traps are not recommended as they tend to draw more beetles to the area than they remove.
Bushes can withstand significant feeding injury without yield impact but fruit contamination with feces may be unacceptable, especially for packout.
Admire Pro rate is for foliar applied; see label for soil applied rate.
 
The use of Sevin may result in the build up of aphids due to the elimination of natural predators.
 
Surround labeled for suppression only.
 
Aza-Direct acts as a feeding repellent and requires frequent reapplication.
 
When applying nematodes, water after application and keep soil moist two weeks after application.  
 
   
 
 
Anthracnose
 
Same as First Cover above
 
See Captan comments in Petal Fall Section.
Powdery mildew
 
Same as First Cover above
 
 
Spotted wing Drosophila
 
Same as First Cover above
 
 
Post-harvest
Sharp-nosed leafhopper
IRAC
4A
3
3
3
3
1A
1B
1A
 
Actara, 3-4 oz (3)
*Asana XL, 4.8-9.6 oz (14)
*Bifenture 10DF, 5.3-16.0 oz (1)
*Brigade WSB, 5.3-16 oz (1)
*Hero, 4-10.3 oz (1)
*Lannate LV, 1.5 pt (3)
Malathion 5E, 2.5-3 pt (1)
Sevin XLR Plus, 1-2 qt (7)
Rogue out plants affected with blueberry stunt.
Monitor insects with yellow sticky traps and control when found.
Each of these sprays will control sharp-nosed leafhopper, the only known carrier of the blueberry stunt mycoplasma.
Powdery mildew
 
Same as Second Cover above
Plant resistant cultivars when possible.
Plant and prune for good air circulation and drying conditions.
Do not use sulfur products and oil products within 2 weeks of each other.
Phomopsis twig blight
FRAC
M02
 
Miller Lime Sulfur, 5 gal (0)
 
Apply in late October or when 2/3 of leaves drop on Weymouth and Berkeley.
Where brand names for chemicals are used, it is for the reader’s information. No endorsement is implied, nor is discrimination intended against products with similar ingredients. Please consult pesticide product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.
RAC=Resistance Action Committee group for resistance management.  Fungicides=FRAC, Insecticides=IRAC
*Restricted use pesticide; pesticide applicators license required. OMRI listed for organic production. (UN) unknown mode of action.
For resistance management do not make more than 2 sequential applications of fungicides in the same FRAC group or insecticides in the same IRAC group. See product labels or RAC column in this table for groups.

Vertebrate Pests

Deer: White-tailed deer can cause extensive damage to blueberries by browsing top-growth in winter. Deer can also cause damage to other small fruit crops. For more information on controlling deer, please see Deer Control in the Appendices.

Birds: Birds are a major pest problem in highbush blueberries. Left unchecked, they can destroy enough of the crop to ruin profitability of a planting. The loss of chemical deterrents has made bird control a more difficult task in recent times, but effective means are still available.

Management: Netting is the most effective way to keep birds out of the planting. Although initial costs can be high, most netting will last for many years if cared for properly. Netting should be hung over some sort of support structure built around the planting. Usually posts are set nine feet above the ground around the perimeter of the planting, and wire is run from pole to pole to form a grid over the planting. The netting is hung over this grid when fruit begins to turn color. Some temporary nine foot poles may be placed within the planting at intersections of the grid to keep netting from drooping. Bury edges of the netting or anchor it to the ground to keep birds from crawling underneath. Remove netting when harvest is complete, and store in a cool, dry place.

Visual scare devices have variable effectiveness on birds. Scarecrows, balloons, kites, snakes or stuffed owls may work on certain bird species in certain areas, but none seem to have widespread dependability. When using visual scare devices, place in planting only when fruit begins to ripen, and move regularly, at least once a day. Six scare-eye balloons per acre are recommended. Remove from field as soon as harvest is over to reduce birds becoming accustomed to the devices. Kites and helium-filled balloons of hawks positioned high above the planting have provided good results in some areas.

Noise deterrents, such as propane cannons, alarms and recorded distress calls seem to have the least effect on birds in blueberries, and may greatly annoy neighbors. A combination of noise and visuals may be effective, however. Several operations have hired people to regularly drive motorcycles and/or ATVs through plantings when fruit is ripe, and this seems to keep birds away quite well.

Bird Shield™, a repellent formulated from methyl anthranilate, is registered for use on blueberries, cherries, and grapes. Methyl anthranilate is commonly used as a grape flavoring in human food preparations. Bird avoidance is based on odor quality and irritation. To humans, this chemical has a grape-like or fruit odor and a slightly bitter, pungent taste. Unfortunately efficacy data does not support recommending the use of this material at this time.

Research using laser "scarecrows" is currently being conducted. Hopefully these devices will help deter birds in the near future.

Voles: Voles can be a serious problem in blueberry plantings. They feed on the bark of stems or on roots depending on which species of vole is present. In the Northeast, two species are found: the meadow vole (Microtus pennsylvanicus) and the pine vole (Microtus pinetorum). They may both be present in a blueberry planting. It is important to determine which species is present in order to make management decisions.

Size and appearance of the two species differ although it is somewhat rare to actually see them. The meadow vole has a long body (150-195 cm) and long tail, prominent eyes and ears, coarse fur, and is dull gray to chestnut in color with a gray belly. The pine vole has a short body (110-135 cm) and short tail, sunken eyes and ears, fine velvety fur, and is bright chestnut in color with a slate gray belly.

Evidence of their activity is more diagnostic. Meadow voles are active on the surface of the ground, feeding on the bark of the bushes and making shallow trails in the grass or mulch around the plants. Food caches and droppings can be found in these surface trails. Pine voles are active below ground, feeding on roots. Subsurface trails can be found by digging around the bushes. These trails come to the surface where mounds of dirt can be seen. Holes leading into these trails are about 1” in diameter.

Simply finding evidence of voles does not indicate a serious problem. To determine whether the voles are causing serious injury to the bushes, it is necessary to estimate the population of voles present. This requires some specialized sampling. It is best to contact your Extension Specialist for help with this sampling procedure.

Management: In some cases, removal of mulch material around bushes can help in reducing the meadow vole population. However, this is risky for bushes susceptible to drought stress. In those cases, choosing a mulch material that does not support tunneling (caves in easily), such as wood chips, is recommended. In some New England States, any application of toxicants or poisons for the purpose of killing any mammal or bird is prohibited. However, some toxicants may be allowed under certain situations with the proper permits. Call your Extension Specialist for recommendations.

Weeds

The primary goal of weed management is to optimize yields by minimizing competition between the weeds and the crop. Weeds reduce yields by competing with the crop for water, light, and nutrients. Weeds also harbor insects and diseases and encourage vertebrate pests. Timely cultivation, wise use of herbicides, and never permitting weeds to go to seed are integral parts of a good weed management system. Many of the weeds found in these fields are difficult-to-control perennial weeds that are not common in annual crop culture. New plantings usually have fewer perennial weed problems than older plantings. Annual and biennial weeds can also exist in these fields. Fields should be scouted at least twice a year (spring and fall) to determine specific weed problems. The selection of a weed management tool should be based on specific weeds present in each field.

The most important weed management strategy is employed prior to planting that is, eliminating all perennial weeds. Fields that have been dormant or have been in pasture may have perennial weeds that at well established. Fields that have been in cultivation are less likely to have established perennial weeds in them. Common perennial weeds include common dandelion, Canada thistle, stinging nettle, field bindweed, field horsetail, goldenrod, and quackgrass. Once these perennial weeds become established or remain established in a berry field, they are very difficult to remove. The most common way to remove perennial weeds is with Roundup (glyphosate) applied in the fall prior to planting. Perennial broadleaf weeds should be treated after flowering but prior to a killing frost. Perennial grasses can be treated well into November.

Weeds can develop resistance to herbicides. The Weed Science Society of America (WSSA) developed a grouping system based on the mode of action of different herbicides. WSSA Group numbers can be used as a tool to choose herbicides in different mode of action groups so mixtures or rotations of active ingredients can be planned to better manage weeds and reduce the potential for resistant species.

Cultural weed management in blueberry plantings includes mulching, cultivation, and soil pH management. Mulching is a major weed management tool in blueberry production. Mulches that are free of weed seeds and placed thickly enough can be very effective at reducing or eliminating most annual weeds from the crop row. They are seldom effective on perennial weeds, however. Use of cultivation is difficult and often is counter productive in blueberry plantings. It destroys surface feeding roots and does not work well where mulches are used. All cultivations should be timely and shallow to minimize crop root injury, to minimize loss of soil moisture, and to avoid repositioning new weed seeds to the soil surface. The low pH soil that blueberry plantings thrive in is not a good environment for most weed species. Keeping the soil pH at the right level will help to reduce weed pressure.

The areas between the crop row is usually maintained with a mowed cover of sod, clover, weeds, or a combination of these. This cover is used primarily for erosion control and to improve trafficability in the field.

Table 36. Weed Management for Highbush Blueberries

Table 36. Weed management for highbush blueberries in the transplant year and in established plantings.
Weed Problem Herbicide Rate/Acre Comments and Limitations
PLANTING YEAR
PREEMERGENCE WEED CONTROL
Annual broadleaf weeds (mesotrione) Group 27
Callisto Herbicide
3-6 oz Add nonionic surfactant to be 0.25%% of the spray volume, or 1 qt per acre crop oil concentrate. Apply in the late fall after leaf drop and/or in early spring before bud break as a spray directed toward the base of the bush. Broadleaf weeds controlled include horseweed and common lambsquarter. Tank-mix with an appropriate postemergence herbicide for broad-spectrum control of emerged weeds. Tank-mix with a residual grass herbicide to improved annual grass control. Do not apply more than 6 fl oz of Callisto per acre within one year.
Annual broadleaf weeds
and suppression of annual grasses
(flumioxazin) Group 14
Chateau SW
6 oz Only if plants established less than 2 years are protected from spray contact by nonporous wrap, grow tubes, or waxed containers. Add crop oil concentrate to be 1% of spray volume. Apply in late fall after leaf drop or in early spring before bud break. Tank-mix with an appropriate postemergence herbicide for broad-spectrum control of emerged weeds. Tank-mix with a residual grass herbicide to improve annual grass control. Do not allow spray to contact foliage or new green bark. Do not use more than 6 oz/a of product where the soil contains more than 80% sand until the plants have been in the field for more than 3 years. Follow instructions on label for tank clean-out if any part of the sprayer will be used to spray other crops; otherwise, crop injury may occur. See label for other cautions and restrictions, as even contact with treated residue can cause phytotoxicity.
Annual grasses and small seeded broadleaf weeds (napropamide) Group 15
Devrinol 50 DF
Devrinol 2-XT
Devrinol DF-XT
8 lb
2 gal
8 lb
Apply after transplanting to weed-free soil. Devrinol must be activated within 24 hrs by cultivation or enough water by irrigation or rainfall to wet the soil to a depth of 2 to 4 inches. The full rate may not be necessary at transplanting.
(oryzalin) Group 3
Surflan DF
2.4 - 7.1 lb Do not apply until soil has settled around the plants and no cracks are present. Irrigation or 1 inch of rain is needed within 21 days of application. Shallow cultivation will improve control. May injure newly planted tissue culture plants.
(S-metolachlor) Group 15
Dual Magnum EC
0.67 pt Apply as a banded treatment to either side of the blueberry rows prior to weed emergence. Avoid contact with the crop. Blueberry bushes planted in coarse soils are more susceptible to injury than those on fine-textured soils. MASSACHUSETTS ONLY: Indemnified label available only at www.farmassist.com. Read entire label for other precautions.
(simazine) Group 5
Princep 4L
Caliber 90
 
1 - 2 qt
1.1 - 2.2 lb
Use to improve the broadleaf weed activity of Devrinol or Surflan. Consider applying half the maximum rate after planting and half in the fall before winter annuals emerge. Do not use on newly transplanted tissue culture plants.
(isoxaben) Group 29
Gallery 75D
Trellis
0.66 - 1.33 lb
0.66 - 1.33 lb
NON-BEARING USE ONLY. Do not apply within 1 year of the first harvest. Do not apply over t he top of plants but as a directed spray to thebase of plants after the soil has settled. Does not control emerged weeds. Controls many broadleaf weeds from seed. See label for a complete list.
POSTEMERGENCE WEED CONTROL
Emerged annual and most perennial grasses (fluazifop) Group 1
Fusilade DX
16 - 24 oz NON-BEARING USE ONLY. See label for best times to treat specific weeds. Will not control broadleaf weeds or sedges. Do not apply to crops to be harvested within 1 year of application. Do not apply if rainfall is expected within 1 hour or if grasses are under drought stress. Must be used with a crop oil concentrate or non-ionic surfactant.
(sethoxydim) Group 1
Poast
1 - 2.5 pt See label for best times to treat specific weeds. Will not control broadleaf weeds or sedges. Do not apply to grasses under stress (e.g. drought). Crop oil concentrate must be added to the spray tank. Do not cultivate 5 days before or 7 days after application. Do not apply more than 5 pints per acre per season.
Emerged annual and most perennial grasses
(clethodim) Group 1
Select 2EC
Select Max
Arrow 2EC
 
6-8 oz
12-16 oz
6-8 oz
Use the lower rate to control annual grasses and the perennial grasses listed to the left. Repeat the application if regrowth occurs. Always add oil concentrate to be 1% of the spray solution, or a minimum of 1 pint per acre, to Select 2EC. Always add oil concentrate to be 1% of the spray solution, or a minimum of 1 pint per acre, or nonionic surfactant to be 0.25% of the spray solution to Select Max. Do not tank-mix with any other pesticide unless labeled. Do not apply within 1 hour of rainfall. Do not apply to grasses suffering from drought, heat, cold, or any other stress condition. Select is currently labeled for nonbearing fields only. Do not apply within 12 months of harvest.
Emerged annual weeds and suppression of perennial weeds. (pelargonic acid) Group 0
Scythe
3-10%
solution
Contact material for burn down only. See Scythe comments in Strawberry section. See label for complete instructions.
(glufosinate ammonium)
Group 10
Rely 200
Cheetah
Lifeline

 

77-115 oz
48-82 oz
48-82 oz

Use to burndown emerged weeds. Apply as a banded, broadcast, or spot treatment. Do not apply within 14 days of harvest. Avoid direct contact with crop. Do not exceed 230 oz/acre/year. Do not graze, harvest, or feed sprayed weeds to livestock.
ESTABLISHED PLANTINGS
PREEMERGENCE WEED CONTROL
Annual grasses and small seeded broadleaf weeds (napropamide) Group 15
Devrinol 50DF
Devrinol 2-XT
Devrinol DF-XT
8 lb
2 gal
8 lb
Apply in the early spring before seedling weeds emerge. Devrinol must be activated within 24 hours by shallow cultivation or with enough rainfall or irrigation to wet the soil to a depth of 2 to 4 inches.
(oryzalin) Group 3
Surflan 4AS
Surflan DF
 
2 - 4 qt
2.4 - 7.1 lbs
Apply to weed-free soil in the spring. Irrigation or 1 inch or rainfall is needed within 21 days of application.
(norflurazon) Group 12
Solicam 80DF
2.5 - 5 lb Apply in early spring when crop is dormant to clean and weed-free soil. May result in temporary bleaching or chlorosis of leaves from which the plant will recover. Do not use on nursery stock.
(S-metolachlor) Group 15
Dual Magnum EC
0.67 -1.33 pt Apply as a banded treatment to either side of the blueberry rows prior to weed emergence. Avoid contact with the crop. Blueberry bushes planted in coarse soils are more susceptible to injury than those on fine-textured soils. MASSACHUSETTS ONLY: Indemnified label available only at www.farmassist.com. Read entire label for other precautions.
NOTE: For broad spectrum pre-emregence weed control, consider applying one of the above “grass” herbicides (napropamide, oryzalin, norflurazon, or S-metolachlor) in addition to one of the following “broadleaf” herbicides (simazine, terbacil, hexazinone, dichlobenil, or mesotrione).
Annual and perennial grasses (pronamide) Group 3
Kerb 50WP
2-4 lb Apply in late fall when soil temperatures are between 35 and 55°F. Spring transplants should be at least six months in the field, and fall transplants should be in the field for twelve months prior to treatment. When applied in the fall, also provides early control of annual grasses the following spring. Apply Surflan, Solicam, or Sinbar the following spring for full season annual grass control. Tank-mix Kerb with Princep for residual broadleaf weed control.
Annual broadleaf weeds (mesotrione) Group 27
Callisto Herbicide
3-6 oz Add nonionic surfactant to be 0.25% of the spray volume, or 1 qt per acre crop oil concentrate. Apply in the late fall after leaf drop and/or in early spring before bud break as a spray directed toward the base of the bush. If applying in the fall, use a 3 fl oz rate and repeat with 3 fl oz prebloom for longer control. If applying in the spring, up to 6 fl oz can be used. Broadleaf weeds controlled include horseweed and common lambsquarter. Tank-mix with an appropriate postemergence herbicide for broad-spectrum control of emerged weeds. Tank-mix with a residual grass herbicide to improved annual grass control. Do not apply more than 6 fl oz of Callisto per acre within one year.
(halosulfuron) Group 2
Sandea 75 WSG
0.5-1 oz

For control of broadleaf weeds and nutsedge. Apply a single or sequential application based on weed pressure. If small weeds are present, tank-mix with a post-emergence broad-spectrum type herbicide to maximize and enhance the spectrum of broad-leaf and grass control. Do not apply Sandea to plants established less than 1 year or to plants under stress. Do not apply more than 2 oz Sandea per acre per 12-month period. Check plant-back interval before establishing a new crop on Sandea-treated areas (i.e. 36 months for strawberries).

For nutsedge control, make a single application when nutsedge is fully emerged (3-5 leaf stage). If a second application is needed, it may be made later in the season directed to secondary nutsedge emergence. For best results use a minimum of 0.75 oz/A Sandea.

Annual broadleaf weeds and supression of some annual grasses (flumioxazin) Group 14
Chateau SW
6-12 oz Add crop oil concentrate to be 1% of spray volume. Apply in late fall after leaf drop or in early spring before bud break. Tank-mix with an appropriate postemergence herbicide for broad-spectrum control of emerged weeds. Tank-mix with a residual grass herbicide to improve annual grass control. Do not allow spray to contact foliage or new green bark. Do not use more than 6 oz/a of product where soil contains more than 80% sand until plants have been in the field for more than 3 years. Follow instructions on label for tank clean-out if any part of the sprayer will be used to spray other crops; otherwise, crop injury may occur. See label for other cautions and restrictions, as even contact with treated residue can cause phytotoxicity.
(rimsulfuron) Group 2
Solida

4 oz

For broadcast applications, make a single application preemergence or early postemergence to actively growing weeds at 4 ounces per acre per year . Use a directed spray application adjusted to provide complete coverage of the weeds while minimizing the amount of spray coming into contact with blueberry plants. When applied as a banded treatment (50% treated band or less), Solida may be applied twice per year. Allow a minimum of 30 days between applications. Applications made after bud break may cause temporary chlorosis and/or stunting of leaves contacted by the spray. Use on high bush blueberries that have gone through at least one growing season and are in good health and vigor. May be applied in tank mixture with other herbicides registered for use in high bush blueberries. Do not apply within 21 days of first harvest (21 day PHI). Do not apply more than 4 ounces per acre on a broadcast application basis per year.

Broadleaf weeds, some grasses, and suppression of some perennial weeds (simazine) Group 5
Princep 4L
Caliber 90
 
2 - 4 qt
2.2 - 4.4 lb
Apply in the spring before bud break and before weeds emerge, or in the fall. Do not apply when fruit is present. For improved control as well as quackgrass suppression apply half in the spring and half after harvest.
(terbacil) Group 5
Sinbar 80WP
Sinbar WDG
 
2-3 lb
2-3 lb
Apply in the early spring or in the fall as a directed spray to the base of the plants. Will also control small emerged weeds. Do not contact new shoots and avoid contact with foliage. Spring application must be made before fruit set. Avoid application on plantings low in vigor. Planting must be at least 1 year old before application. Do not apply within 70 days before harvest.
(hexazinone) Group 5
Velpar 75DF
Velpar L
 
1.3 - 2.6 lb
4 - 8 pt
Planting must be established at least 3 years. Apply in the spring to the soil surface PRIOR to blueberry leaf emergence. Use a directed spray to avoid contact with blueberry plants. Controls many perennial weeds and will suppress wild brambles.
(dichlobenil) Group 20
Casoron CS
Casoron 4G
 
1.4-2.8 gal
100-150 lb
Apply at temperatures below 50˚F, preferably just before rain or snow. Soil must be settled around established plants. Uniform application is essential. Do not apply during new shoot emergence. The 4G formulation is effective on many perennial weed species. May reduce plant growth in plantings that are young or lacking vigor. There is a leaching risk with this product however both the granular (4G) and microencapsulated (CS) formulations have reduced leaching potential compared to the wettable powder formulation used previously. Use higher rate for perennial weeds. Do not apply until 1 year after planting. Tank mixing with other pre-and/or post-emergence herbicides registered for use on the specific crops listed may provide a broader spectrum of weed control.
  (sulfentrazone) Group 14
Zeus XC
Zeus Prime
8 - 12 oz
7.7-15.2 oz

If adequate moisture (1/2" to 1") from rainfall or irrigation is not received within 7 to 10 days after treatment, a shallow incorporation may be needed. Apply to blueberries growing at least 3 years and in good condition. Should be applied when no weeds are present. If weeds are present, tank mix with a postemergence herbicide. Can be tank mixed with other preemergence and postemergence burndown herbicides. Refer to the tank mix partner’s labels for additional restrictions. Burndown herbicides may include, but are not limited to, Aim, glyphosate, paraquat, glufosinate, and 2,4-D. Do not tank mix with Chateau® herbicides (flumioxazin) or with other products containing sulfentrazone.  May be applied twice per year. Do not apply more than 12 fl oz product per acre (0.375 lb ai/A) on a broadcast application basis per year. Allow a minimum of 60 days between applications.
Zeus Prime is a combination of carfentrazone-ethyl plus sulfentrazone
 
POSTEMERGENCE WEED CONTROL
Emerged annual grasses and broadleaf weeds. Suppression of emerged perennial weeds (paraquat) Group 22
*Gramoxone SL 2.0
Firestorm 3SC
 
2-4 pt
1.3-2.7 pt
Contact herbicide with no translocation or residual activity. Best results occur when weeds are 2 inches tall or less. Regrowth may occur from the root systems of established weeds. Use a surfactant to be 0.25% of the spray solution (1 qt per 100 gallons of spray solution). Combine with recommended preemergence herbicide(s) for residual weed control. Do not allow spray or drift to contact green bark, leaves, or fruit. Crop damage may result. The use of shields, such as grow tubes or paper milk cartons greatly reduces the risk of injury in young plantings. DANGER: Do not breathe spray mist. Read safety precautions on the label.
(glufosinate ammonium)
Group 10
Rely 200
Cheetah
Lifeline
 
77-115 oz
48-82 oz
48-82 oz
Use to burndown emerged weeds. Apply as a banded, broadcast, or spot treatment. Do not apply within 14 days of harvest. Avoid direct contact with crop. Do not exceed 230 oz/acre/year. Do not graze, harvest, or feed sprayed weeds to livestock.
(carfentrazone ethyl)
Group 14
Aim EC
Zeus Prime
 
1-2 oz
7.7-15.2 oz
Apply as a directed spray to the base of the crop to burn down emerged weeds including morningglory, nightshade, bedstraw, and ferns. Do not use more than 6.1 oz/year. Contact with the crop will cause damage. Zeus Prime is a combination of carfentrazone-ethyl plus sulfentrazone.
 
 
Emerged annual and most perennial grasses (sethoxydim) Group 1
Poast
1- 2.5 pt Effective on actively growing grasses. Do not apply to grasses under stress (e.g., drought). Crop oil concentrate must be added to spray tank. Do not cultivate 5 days before or 7 days after application. Do not apply within 30 days before harvest in blueberries. Do not exceed 5 pints per acre per year.
(clethodim) Group 1
Select Max
9-16 oz Apply as a directed spray to the base of the crop and to actively growing grasses. Grasses under drought stress will not be controlled. Do not apply more than 64 oz/acre/year. Do not repeat applications within 14 days.
Emerged annual weeds and suppression of perennial weeds (pelargonic acid)
Fatty acid, Group 0
Scythe
3-10% solution Contact material for burn down only. See Scythe comments in Strawberry section. See label for complete instructions.
Emerged annual and perennial weeds (glyphosate) Group 9
Roundup Ultra
1 - 5 qt Apply to actively growing weeds. Apply with a wiper or a shielded/directed spray to the base of the plants. Do not permit herbicide solution to contact desirable vegetation, including green shoots, canes, or foliage. Do not cultivate within 7 days after application.
†Where brand names for chemicals are used, it is for the reader’s information. No endorsement is implied, nor is discrimination intended against products with similar ingredients. Please consult pesticide product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.
*Restricted use pesticide; pesticide applicators license required. OMRI listed for organic production
Table 37. Weed management with and without herbicides in a blueberry planting
Year Month Herbicide Options Non-herbicide Options
Planting year
  Fall prior to planting Roundup for emerged perennial weeds 30 days before planting. After weed dieback till to prepare for planting. Frequent tillage
  April-May Surflan or Devrinol before seedlings emerge. Till or water in within 24 hours Hand weed
  Mid-June after planting Fusilade, Poast, Select, or Arrow for perennial grasses Cultivate/handweed/mulch; mow row middles and borders
  Mid-July Hand weed or Roundup spot treatments Cultivate/handweed; mow row middles and borders
  October Princep at low rate Cultivate/handweed; mow row middles and borders
  November Callisto or Chateau for broadleaves. Kerb for grasses before ground freezes. Casoron for grasses and broadleaf weeds. Read labels carefully for specific application requirements Handweed
Fruiting years
  March-April Callisto, Casoron, Chateau, Sandea, Sinbar, Princep or Velpar for broadleaf weeds. Devrinol, Solicam or Surflan for grasses. Handweed and apply mulch as needed
  Early May Gramoxone or Scythe before new cane emergence. Handweed and mow row middles and borders
  Late July after harvest Select or Poast on actively growing grasses, spot treat with Roundup Handweed and mow row middles and borders
  September to October Sinbar (after harvest), Devrinol, Solicam, Surflan, Princep. See labels for restrictions. Handweed and mow row middles and borders
  November; after crop dormancy Callisto or Chateau for broadleaves. Kerb for grasses. Casoron if needed for grasses and broadleaves. See labels for restrictions. Handweed