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, space, 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 crop 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 are 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 late 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.
| Weed Problem | Herbicide | Rate/Acre | Comments and Limitations |
|---|---|---|---|
| PLANTING YEAR | |||
| PREEMERGENCE WEED CONTROL | |||
| Annual broadleaf weeds | (mesotrione) Group 27 Callisto |
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 0 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 21 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 the top of plants but as a directed spray to the base 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 young annual and perennial grasses. 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 in 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 |
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 0 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 29
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! Restricted-use herbicide. May be fatal if swallowed or inhaled. Read safety precautions on the label. See notes below. |
|
(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 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. OMRI listed for organic production |
|||
| 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. | Handweed | |
| Mid-June after planting | Fusilade, Poast, Select, or Arrow for perennial grasses | Cultivate/handweed/mulch; mow row middles and borders | |
| Mid-July | 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 | |
NOTES
Alion (indaziflam) - Use preemergence. Apply only to bushes that are at least 1 year old and exhibiting good growth and vigor. A dry soil surface at time of application and 48 hours after application is optimum for binding the active ingredient to soil particles and preventing its downward movement to the crop’s roots. Moisture is needed for activation of Alion Herbicide. Dry soil conditions following the initial 48-hour period after application of Alion Herbicide may result in reduced weed control. Controls selected broadleaves and grasses. Exercise caution with this product around or near water bodies.
Karmex DF/Diuron 4L - Many formulations are available; be sure to verify that you can use your selected product in your state. Controls many annual and perennial grasses and herbaceous broadleaf weeds. Although this herbicide can have postemergence control, it seems best when applied preemergence. Best results are seen when herbicide is activated with water within 2 weeks of application.
QuinStar (quinclorac) - A systemic herbicide with plant uptake occurring through both the foliage and roots. Resultant herbicide symptoms on susceptible plants include twisting, stunting, reddening and chlorosis. For annual plants, symptoms may take up to two weeks after application to develop with death occurring in about three weeks. For perennial weeds, symptoms may not be evident for several weeks after application and full effect may not be evident for 3 to 6 months. May affect desirable nearby species; check label.
For the first application apply up to 12.6 fluid ounces per acre (0.375 lb ai/A) of QuinStar® 4L at the end of dormancy, prior to budbreak. For highbush blueberries, apply as a banded, soil application on each side of the blueberry plants. For lowbush blueberries, apply as a broadcast, soil application. A second application may be made up to 30 days prior to harvest. For highbush blueberries, apply up to 12.6 fluid ounces per acre (0.375 lb ai/A) of QuinStar® 4L as a banded application to the ground on each side of the blueberry plants. For lowbush blueberries, apply the second application as a broadcast, soil application to the ground. A crop oil concentrate at a rate of 2 pints per acre may be included in the spray mixture.
Suppress EC - nonsystemic, nonselective postemergence foliar burndown herbicide for control of annual and perennial broadleaves and grasses. Best on newly emerged plants, less than 6 inches in height. OMRI-approved product.
Axxe - nonsystemic, nonselective postemergence, foliar burndown herbicide. Use higher rates on bigger plants. Very toxic to fish and invertebrates. Do not contaminate water resources during use. Eye irritant. OMRI-approved product.