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Healthy Fruit 2010 Vol. 18:14

Jul 13, 2010

Orchard Radar insect synopsis (for Belchertown)

First dogwood borer (DB) egg hatch roughly: June 15. Peak hatch roughly: July 22

Codling moth (CM) development as of July 13: 2nd generation adult emergence at 26% and 2nd generation egg hatch at 3%. In most orchards, insecticide targeted against plum curculio and apple maggot prevent codling moth damage. If targetted codling moth control is needed, key management date is: 2nd generation 7% CM egg hatch: July 15, Thursday (= target date for first spray where multiple sprays needed to control 2nd generation CM)

Spotted tentiform leafminer (STLM): Rough guess of when 2nd generation sap-feeding mines begin showing: June 24, Thursday. Optimum first sample date for 2nd generation STLM sapfeeding mines is June 30, Wednesday. Second optimized sample date for 2nd generation STLM sapfeeding mines, if needed: July 7, Wednesday. Third optimized sample date for 2nd generation STLM sapfeeding mines, if needed: July 15, Thursday

2nd generation White Apple Leafhopper (WAL) found on apple foliage: July 22, Thursday

Orchard Radar preliminary McIntosh harvest date forecasts (for Belchertown)

Date to apply ReTain to delay harvest for apples which without treatment would be ready for storage harvest on August 25 is Wednesday, July 28

Begin measuring actual McIntosh starch-iodine index no later than Wednesday, August 18

The Michigan formula estimate for standard (i.e. non-spur) McIntosh starch index 4.0 and beginning of optimum McIntosh harvest for CA storage is Wednesday, August 25. Estimate adjusted to lessen influence of unusual bloom date is Tuesday, August 31

Cornell Bulletin 221 provides formulas for different locations to estimate date when non-spur McIntosh reach starch index 6.0 and the end of optimum harvest for CA storage. Using the Hudson Valley formula, the estimated end of McIntosh CA harvest for Belchertown MA is Wednesday, September 15

The way I see it

The heat and dry weather has kind of put a damper on a lot of things including diseases, but surprisingly, insect activity is not all that prevalent. Very few reports of high apple maggot or mite numbers have been coming in, although that could change fast I suppose. Japanese beetles are around but not in excessive numbers like years past. Even potato leafhoppers are not all that bad. All that being said, it is early still so keep an eye on things. We seem to already be turning the corner to harvest as early peaches are being picked in earnest and early apples will start in just a few weeks. I maintain most everything will be 7-10 days ahead of 'average' so be prepared. Maybe McIntosh will actually be 'ready' to pick on Labor Day this year. :-)

Time to collect leaves for foliar analysis

It's not too early to start collecting leaves for foliar (plant tissue) analysis to determine nutrient status. Foliar/leaf analysis is the best way to get a snapshot of the nutrient content of your trees, and thus tailor fertilizer programs to address deficiencies or excess of nutrients as indicated by the leaf analysis results. Complete directions for collecting and submitting the leaves are here on the UMass Soil and Plant Tissue Testing Laboratory. (One form also included with this Healthy Fruit that can be copied if you are submitting multiple samples.) Consider sampling every block every three years of so you can best address the nutrient needs of your trees. Note that you can analysis can be done for apples, peaches, pears, cherries, etc. If you have any questions let me know. JC

Guest article

STINKIN' UP THE PLACE Peter Jentsch, Cornell's Hudson Valley Lab. Reprinted from Scaffolds Fruit Journal, July 12, 2010.

Stink bugs (Heteroptera: Pentatomidae) are generally native to our region and are notable examples of locally migratory insects that live on a broad complex of plant hosts. Principal hosts found along the orchard edge or resident within herbicide strips include mullein, mustard, dock, plantain, milkweed, mallow, morning glory, thistles, vetch, and velvet grass. These adult "seed-feeders" most often enter our orchards during the dry periods of the season as host plants dry out. Irrigated tree fruit becomes very attractive to the stink bug complex during drought conditions, leading to late season feeding damage in pear, apple and peach orchards. Their mouthparts are designed to pierce the fruit skin and draw out the cellular contents of the fruit flesh, leaving behind dry cell walls that appear as corking when peeled.

The complex of stink bugs includes the green, brown and brown marmorated stink bug (Acrosternum hilare, Euschistus servus and Halyomorpha halys, respectively). The green and brown stink bugs are native to the region and are found throughout the state, while the brown marmorated stink bug is a newly emerging pest on fruit in the northern mid-Atlantic region and lower New York State. As you might suspect, stink bugs derive their name from the production of pungent and offensive chemicals released when they are disturbed. Relatively mild winters and reduced insecticide programs may help in fostering their overwintering success.

A recent addition to this complex, the brown marmorated stink bug, made its appearance in Highland, NY during the fall of 2008. A handful of specimens were brought into my office by a distraught gentleman looking for a way to rid them from his home. This species' native range is China, Japan, Korea, and Taiwan; it evidently is a firstclass hitchhiking pest, observed in cargo containers from Asia, and is able to maintain its grip to automobile radio antennas racing along the Pennsylvania turnpike. It has now been identified in parts of New Jersey, Maryland, Delaware, Connecticut, and the southern tier of New York.

The brown marmorated stink bug has distinct alternating light and dark bands on the antennae, and darker bands on the overlapping membranous area at the rear of the front pair of wings. It has copper, bluish-metallic tinted depressions on the head and pronotum not exhibited in other species of regional stink bugs. It is known to feed on a wide variety of host plants, including apple, peach, fig, mulberry, citrus fruits and persimmon, along with ornamental plants, weeds, and soybeans. It has been observed feeding on tree fruits in the U.S., resulting in the characteristic "catfacing," on peaches, which renders fruit unmarketable. It also can be an urban nuisance pest, as it seeks protected overwintering sites in and around homes.

Methods for scouting and managing the stink bug complex can be elusive, due to the lack of technical monitoring tools and the economic thresholds traditionally used in insect pest scouting and management. The first level of management for this pest is determining the level of damage your farm has experienced over the past five years. Drought conditions in the Hudson Valley during the latter part of the last few growing seasons have provided ideal conditions for adult stink bug migration and subsequent fruit injury. Weeds can play an important role in stink bug abundance, thus field proximity to weedy areas often results in higher populations and damage.

It's important to note that stink bug feeding differs dramatically among stone fruit, apple and pear. "Catfacing" injury to peaches by stink bug is very similar to that of the plant bug complex. Stone cells naturally occurring in pears are more pronounced in fruit with stink bug feeding injury as cell contents are removed and the thickened cell walls of stone cells remain. However, on apple, fruit damage appears as shallow, circular, light brown to white spongy pockets in the fruit flesh, usually from 5–10 mm in circumference, and 5–8 mm in depth. Stink bug feeding can easily be mistaken for cork spot (bitter pit). Typical feeding injury tends to be on the stem end or sides of the fruit, as those parts of the fruit surface are easier for the insect to stand on, and most likely to be covered by foliage, which provides protection as the bug feeds.

On apple, stink bug feeding and cork spot are distinguishable by several differences in the depressions on the apple surface. With stink bug feeding, the edge of the depression on the fruit surface is gradual instead of abrupt, as observed with cork spot. The corky flesh is always immediately beneath the skin in stink bug injury, and often separates from the skin. Stink bug injury always has a small puncture near the center of the feeding depression, requiring magnification to observe the feeding site. Occasionally, stink bug feeding may leave a "feeding sheath" within the flesh and protruding above the fruit surface.

Mark Brown, research entomologist at the USDA Appalachian Fruit Research Station in Kearneysville, WV, found that most stink bug damage occurs between 26–60 days before harvest. He has observed that 'Braeburn', 'Jonagold', 'Granny Smith' and 'Stayman' tend to have high stink bug injury levels at harvest, whereas 'Imperial Gala', 'Lawspur Rome', and 'Red Fuji' have been observed to have lower levels of stink bug injury.

Stink bugs are very difficult to manage for a number of reasons. They have a broad host range, including many crops and broadleaf weeds. They are highly mobile, frequently moving between weed hosts and fruit trees. They tend to be more active in the evening and during the night. Insecticide applications made during the day may not come in direct contact with the insect, subsequently reducing the effectiveness of the materials. Therefore, stink bugs are not continually exposed to insecticide residues for long periods of time, as are most other insect pests in managed orchards. Consequently, effective management of stink bug points toward repeated applications of insecticides, especially along the borders of orchards during the period of "adults in flight" late in the season.

Hudson Valley Laboratory studies conducted on apple in 2006 demonstrated reductions in stink bug feeding damage with Thionex 50WP (endosulfan), Warrior 1CS (lambda-cyhalothrin) and Danitol 2.4EC (fenpropathrin) treatments at 2-week intervals. The use of Thionex against aphids and leafhoppers will provide incidental control of stink bug (which is not on the label). Thionex has a 21-day PHI, with a maximum of 2 applications during the fruiting season at a maximum labeled rate of 5.0 lbs/A and a maximum seasonal use limit of 6.0 lbs/A. Danitol has a 14-day PHI, does include stink bug on the label, and (in NY) has a 16.0 fl oz/A rate allowed for stink bug, with a maximum limit of 32 fl oz/A per season. Danitol will give some control of European red mite, apple maggot, the internal lep complex and the leafhopper complex. Warrior has a 21-day PHI, also includes stink bug on the label, with a 2.56–5.12 fl oz/A use range for stink bug, and a maximum use rate of 20.48 fl oz/A per year post-bloom. Warrior gives some control of apple maggot, the internal lep complex and the leafhopper complex. Pyrethroids in general are less effective in hot weather and may cause late season mite flare-up.

Useful links

UMass Extension Fruit Program

UMass Cold Spring Orchard

Scaffolds Fruit Journal

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