Insects | Credits
Volume 7, No. 8 May 11, 1998
43F 50F Current DD accumulations (Geneva 1/1-5/11): 520 280 (Geneva 1997 1/1-5/11): 302 138 (Geneva "Normal" 1/1-5/11): 350 164 (Highland 1/1-5/11): 701 383 Coming Events: Ranges: Redbanded leafroller 1st flight peak 180-455 65-221 Spotted tentiform leafminer flight peak 180-544 65-275 San Jose scale 1st catch 189-704 69-385 Comstock mealybug 1st gen crawlers in pear buds 220-425 82-242 Oriental fruit moth 1st flight peak 259-606 96-298 Codling moth 1st catch 273-805 141-491 Spotted tentiform leafminer sap-feeders present 295-628 130-325 American plum borer 1st flight peak 360-962 134-601 European red mite summer eggs present 448-559 235-320 Lesser appleworm 1st flight peak 372-851 181-483 Pear psylla hardshells present 463-651 259-377 Mirid bug hatch complete 532-720 252-390 McIntosh at fruit set 467-648 242-339 Phenologies (Geneva): Apple (McIntosh) - Petal Fall (Red Delicious) - Petal Fall Pear (Bartlett) - Fruit Set Sweet Cherry (Darrow) - Fruit 10mm Tart Cherry (Montmorency) - Petal Fall Peach - Shuck Split Plum - Fruit Set (Highland): Apple (McIntosh) - Fruit Set (Red Delicious) - Fruit Set Pear (Bartlett) - Fruit 10mm TRAP CATCHES (Number/trap/day) Geneva: 4/27 4/30 5/4 5/7 5/11 Spotted Tentiform Leafminer 375 580 741 589 85.5 Redbanded Leafroller 4.8 8.5 12.6 7.0 4.8 Oriental Fruit Moth (apple) 6.0 11.2 8.0 2.2 3.3 Lesser Appleworm - - 1.9* 4.0 7.0 Codling Moth - - - 1.3* 1.4 San Jose Scale - - - 0 0.5* American Plum Borer - - - 0.7* 1.1 Lesser Peachtree Borer - - - 0.2* 0.1 Highland (Dick Straub, Peter Jentsch): 4/20 4/24 4/27 5/4 5/11 Pear Psylla (eggs/leaf) 9.6 - 16.3 12.8 2.1 Pear Psylla (nymphs/leaf) 0.7 - 2.3 3.7 - Pear Psylla (hardshells/leaf) - - - 0.2 0.3 Spotted Tentiform Leafminer 0.1 404 17.2 18.3 7.4 Redbanded Leafroller - 34* 8.3 7.4 2.3 Oriental Fruit Moth - 2.5* 2.3 3.0 1.0 Lesser Appleworm - 0 0 0 0 Codling Moth - 0 0 0.1* 0 Obliquebanded Leafroller - 0 0 0 0 * 1st catch PEST FOCUS Geneva: Codling Moth and San Jose Scale 1st catch in apple 5/7 (Begin accumulating degree days base 50 F from 5/7 to determine timing of codling moth spray). American Plum Borer and Lesser Peachtree Borer 1st catch in cherry and peach 5/7. Highland: Plum Curculio damage observed 5/7. 1st Spotted Tentiform Leafminer mines observed. European Apple Sawfly damage observed on apple fruitlets.
by Art Agnello and Harvey Reissig
This is probably past the point of being timely for many of the orchards in the eastern parts of the state, but even with a weekly format, it's difficult for us to keep on top of the schedule when a season has the starts and stops we've seen during the past few weeks. Weather allowing, many western N.Y. orchards will be entering the petal fall period this week, which is the pivotal time for establishing a foundation for the control of many of the most important arthropod pests. Here are a few points to keep in mind for the petal fall insecticide sprays:
Because tree development this year was earlier and more rapid than normal, European red mite management strategies will need to compensate for some atypical situations this season. First, the trees in many spots were well into the pink bud stage before the first mite eggs began to hatch, so it might be tempting to think that mite population development is 'delayed' this year. However, the post-hatch weather has been more favorable than normal for mite growth, so if anything, the mites are probably better primed for a rapid buildup than they normally would be by this date. Furthermore, although spraying conditions were fairly acceptable during the prebloom period, it didn't last long enough for many people to complete their tight cluster or pink miticide sprays, so there's probably going to be a lot of waiting-until-they-show management decisions this summer.
This approach is possible of course, especially with the availability of a good threshold-response product like Pyramite, but it carries the implicit requirement of vigilant monitoring for threshold numbers and timely action when a rescue treatment is needed. This summer has all the markings of being longer and warmer than normal, which could enable red mites to complete an entire extra generation before bowing out in the fall. High numbers and significant leaf damage can develop very rapidly under such conditions.
European red mite adult female
Our message, not surprisingly, is that it is always wise to keep an eye on the foliage throughout June and July to detect unreasonable mite buildup, because it doesn't take much to boost numbers into the problem category. Until June 30, we recommend a threshold of 2.5 motile stages (anything except eggs) per leaf. You can determine the mite densities on the foliage by using the presence/absence technique.
Examine intermediate-aged leaves (from the middle of the fruit cluster) for motile stages. Check at least 50 leaves (5 per tree), for the presence of any number of mites; no treatment is recommended if <62% of the leaves examined are infested. A sequential sampling table (p. 91) and chart (p. 98) are provided in the Recommends. The choices are as follows if you detect over-threshold levels:
Pyramite applied in a timely manner should generally do the best job, and is most likely to give you control for the remainder of the season, but don't stop examining the foliage altogether. It's advisable not to use this product more than once per season, even though 2 applications are allowable. This is not only out of consideration for potential resistance development, but also because Pyramite has some toxicity to predator mites, and hitting them twice won't do much to allow their establishment.
Kelthane can be used if you have no reason to suspect resistance in your populations, or if none has been applied in a given block for at least 5 years.
Carzol is another choice if you don't mind eliminating any predator mites in the block; back-to-back sprays of this product would probably be needed.
WALH nymphs can be numerous in some blocks, especially in the eastern part of the state. Provado has proven itself effective against this pest, and a petal fall application also gives leafminer control. Furthermore, it will have an added effect on green aphid populations, which might otherwise be more problematic this spring, owing to the advanced tree development and sustained availability of succulent green tissue.
Newly hatched white apple leafhopper nymph
Plum curculio adults move into orchards from overwintering sites in hedgerows or the edges of woods and are present in the trees from late pink to early bloom before the fruit is susceptible to damage. Adults are active in the spring when temperatures exceed 60 F, which means that more than likely they've already started. Adult females oviposit in fruit during both day and night but feed mostly at night. Depending on temperature, overwintering adults remain active for two to six weeks after petal fall.
Plum curculio adult
Although adults may feed on blossoms, apples are not susceptible to damage until petal fall, at which time adults damage fruit by both feeding and ovipositing. Unlike fruit injured by other pests, many apples damaged by plum curculio will remain on the tree until harvest. Because adults are not highly mobile, orchards near overwintering sites, woodlands, and hedgerows are most susceptible to attack. Fruit damage is usually most common in border rows next to sites where adults overwinter.
Dried sap produced by plum curculio feeding and oviposition wounds on apple
Monitoring for plum curculio is not currently recommended in New York because of the amount of time and labor involved and because plum curculio is generally assumed to be present in every orchard. However, various techniques have been used in other areas to monitor plum curculio damage and the presence of adults:
Plum curculio oviposition scars on apple
Several species of wasps parasitize eggs and larvae of plum curculio. Ants, lacewings, and ground beetles prey on larvae in the soil, and some fungi kill larvae. These organisms are not usually sufficient to regulate populations of plum curculio in commercial orchards. Plum curculio is difficult to control completely with insecticides. Relatively high rates and persistent applications are important because of the difficult to predict period of adult activity. In normal orchards that are not near woodlots or hedgerows and have not suffered previous damage, a single application at petal fall will provide seasonal control.
In problem orchards, a petal fall application followed by a second spray 10 to 14 days later will provide adequate control. In orchards with chronic problems, or in seasons when adult activity is prolonged by unusually cool and wet weather, two cover sprays applied 10 to 14 days apart after petal fall may be necessary to prevent late damage. This recommendation derives from a developmental model tested several years in the field at Geneva, which predicts that control sprays are no longer necessary whenever the last spray has been applied with 10-14 days after the accumulation of 340 DD (base 50 F) from petal fall. Guthion, Imidan, Lorsban, and all pyrethroid insecticides are effective at controlling plum curculio. These materials will also control codling moth later on.
Scaffolds is published weekly from March to September by Cornell University - NYS Agricultural Experiment Station (Geneva), and Ithaca - with the assistance of Cornell Cooperative Extension. New York field reports welcomed. Send submissions by 3 p.m. Monday to:
Scaffolds Fruit Journal
NOTE: Every effort has been made to provide correct, complete and up-to-date pesticide recommendations. Nevertheless, changes in pesticide regulations occur constantly, and human errors are possible. These recommendations are not a substitute for pesticide labelling. Please read the label before applying any pesticide.
Return to the Scaffolds 1998 Directory
Return to Scaffolds Home Page
Photographs courtesy of New York State Integrated Pest Management Program