Insects | Credits

SCAFFOLDS Fruit Journal, Geneva, NY                           Volume 4 
Update on Pest Management and Crop Development            May 15, 1995 


                                                     43F       50F
Current DD accumulations (Geneva 1/1-5/15):          406       196
                       (Highland 1/1-5/14):          408       172

Coming Events:                              Ranges:
Tarnished plant bug adults active                 71-536     34-299
Green fruitworm flight subsides                  170-448     75-251
Redbanded leafroller 1st peak                    180-455     65-221
Spotted tentiform leafminer 1st flight peak      180-420     65-217
San Jose scale 1st adult catch                   189-704     69-385
White apple leafhopper nymphs present            236-708    123-404
Codling moth 1st catch                           273-805    141-491
Spotted tentiform leafminer sap-feeders present  295-628    146-325
Oriental fruit moth 1st catch                    323-606    138-298
European red mite egg hatch complete             361-484    183-298
Pear at petal fall                               343-539    144-275
Tart cherry at petal fall                        385-518    185-287
McIntosh at petal fall                           418-561    210-317

Geneva, 5/15
   Apple (McIntosh): Bloom
   Pear: Bloom
   Sweet Cherry (Windsor): Early Petal Fall
   Tart Cherry (Montmorency): Bloom
   Peach: 90% Petal Fall
   Plum: 50% Petal Fall
Hudson Valley Lab, Highland, 5/15
   Apple (McIntosh): 80% Petal Fall
          (R. Del.): Full Bloom

TRAP CATCHES (Number/trap/day)
                                  4/24    5/1   5/8   5/11   5/15
Green Fruitworm                    0.3    2.7   0.8      0    0.3
Redbanded Leafroller               1.0*   0.6   1.3    1.3    2.0
Spotted Tentiform Leafminer        157    371   349    447    492
Oriental Fruit Moth (apple)          0      0   8.9    8.0   57.0
Lesser Appleworm                     0   0.07*  7.5   28.3   28.9
San Jose Scale                       -      -     -      -    0.1*
American Plum Borer (cherry)         -      -     -      -    0.1*

Highland (Dick Straub, Peter Jentsch)
                                  4/24    5/1    5/8  5/15
Green Fruitworm                    0.7      0      0     0
Redbanded Leafroller              10.4    8.7    0.8   0.7
Spotted Tentiform Leafminer       13.0   45.6    6.0   8.2
Oriental Fruit Moth                  0    9.3    0.8   1.0
Fruittree Leafroller                 0      0    0.1*  0.2
Rose Leafhopper nymphs               -      -    1.2  20.3
White Apple Leafhopper nymphs        -      -    0.1* <0.1
European Red Mite motiles            -      -    0.1  <0.1
                                                       * = 1st catch

Geneva: San Jose Scale and American Plum Borer, 1st catch
Highland: Codling Moth and European Apple Sawfly, 1st catch


Highland, NY:       Immature     Mature   Discharged   Tower shoot
5/9                   44%          40%       16%      <2,000 spores


By: Art Agnello & Harvey Reissig, Entomology, Geneva

The effort to circumvent insect pest problems starts its most active phase at this time. Following are a few points to keep in mind for your petal fall insecticide sprays:

  1. To minimize the hazard to honey bees, apply pesticides only after ALL petals have fallen in the block and when no bees are actively foraging on blooming weeds (evening is better than early morning).
  2. Do not use Lannate on early McIntosh, Wealthy, or Dutchess because of possible injury to fruit and foliage.
  3. Postbloom use of any synthetic pyrethroid insecticide has on occasion encouraged the build-up of mites and woolly apple aphid. If a pyrethroid (Asana, Ambush, Pounce) was used in any of the prebloom sprays, do not apply another pyrethroid at petal fall. Try to limit use of these materials to one application per season to delay resistance development and extend their useful field life.
  4. When choosing an insecticide for this application, keep in mind its range of activity, both adverse and beneficial. For example, if Sevin is applied for thinning, it will also help to control plum curculio and white apple leafhopper (even at the 1 lb rate). Carzol acts not only against European red mite, but will also control white apple leafhopper; however, it is not kind to predatory mites.
  5. Be aware of the destructive effects of any spray materials on beneficial mites and insects (refer to Tables 8 and 12 on pp. 37 and 42-44 in the 1995 Recommends.)
  6. Do not use Vydate or Sevin during the first 30 days after bloom without taking into account their thinning effects.


We have seen some impressive overwintered European red mite egg populations this spring, even in blocks that had few mites last year. The weather patterns from last fall through the winter and continuing even now seem calculated to have set us up for a potentially historic mite year. Egg hatch began in earnest last week in most apple blocks around the state; some bona fide treatable populations may have already been noted. Now is the time to keep one eye on the thermometer and the other on mite numbers, because a little warm weather can quickly 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 actually counting them if you want to, but this is more effort than is required. Your time is probably better spent 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. 84) and chart (p. 91) are provided in the Recommends.


WALH nymphs can be numerous in some blocks, especially in the eastern part of the state; growers using Sevin in their thinning sprays will get some control at the 1 lb rate. Alternative choices for control include Thiodan and Lannate; Carzol used for mites now will also do the job, but will be harmful to your predator mites; this first generation is generally not worth the trade-off.


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 60F. 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. 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.

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. Various techniques have been used in other areas to monitor plum curculio damage and the presence of adults:

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 adults may be active for two to six weeks after petal fall depending on temperatures. 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. Guthion, Imidan, Lorsban, and all pyrethroid insecticides are effective at controlling plum curculio. These materials will also control codling moth later on.

The current control strategy is treatment with an organophosphate insecticide at petal fall and the first cover spray in western N.Y., and at petal fall plus the first and second cover sprays in eastern N.Y. Harvey Reissig and Jan Nyrop conducted field tests on oviposition for several years, to find out whether the egg-laying period can be defined in terms of the always variable postbloom weather patterns, especially regarding degree-day accumulations. Their results reinforced a few points we generally try to make each season:

  1. Although plum curculio adults may be in the trees during bloom, they generally do not begin to do any bud-cutting or egg-laying until some time (i.e., 80 degree days, base 50F, or at least a few days) after petal fall.
  2. Unless weather conditions cause an inordinately extended progression from bloom to petal fall to fruit set, perfectly adequate control can be achieved with a timely spray at petal fall and another at first cover (population pressure in the research check plots gave 10% fruit damage).
  3. Application of a pyrethroid at pink does not reduce fruit damage compared with the above post-bloom schedule.


This is a collective common name used in New York to refer to a number of Lepidoptera, but one of the more common members of this group is the speckled green fruitworm, Orthosia hibisci. Traditionally, orchards in eastern N.Y., particularly the Hudson Valley, have had greater problems with GFW than those in the western part of the state. The GFW has a single generation per year and overwinters in the pupal stage in the soil. Adult emergence begins at about green tip and is complete by the pink stage of McIntosh apples. The adults are about 2/3 of an inch long, and are grayish-pink in color with two purplish-gray spots on the forewings. Egg laying begins at about half-inch green. Eggs are laid singly or in pairs. They are white to grayish in color and have ridges radiating from the center. GFW larvae begin hatching between tight cluster and pink. The larvae feed on new leaves, flowers, and developing fruit.

Fruit feeding is normally restricted to larger larvae. The larvae mature between late May and late June, at which time they drop to the ground and pupate in the soil at a depth of 2 to 4 inches. In the past, sprays were applied at pink and petal fall to control the GFW. However, research has indicated that a single spray at petal fall provides comparable control to the two-spray program. Monitoring for the GFW is the same as monitoring for the obliquebanded leafroller, which should take place during the late bloom stage, and both species may be considered together in making a control decision. Pesticides recommended for control of this caterpillar include: Lorsban, Thiodan, Lannate, and the pyrethroids Asana, Ambush, or Pounce.


EAS is an introduced pest and its natural enemies in the United States have been little studied. It overwinters in a puparium in the soil, and adults emerge at the beginning of bloom. Eggs are laid in blossoms at the base of the stamens and hatch in one to two weeks. Larvae feed below the skin near the apple calyx in a spiral pattern that will cause scarring around the circumference of the fruit at harvest. The larvae then molt and feed deeper inside the apple, causing the fruit to abort. Sawfly damage can be distinguished from that of internally feeding lepidopterous larvae because sawfly exit holes are covered with reddish-brown frass pushed out by the feeding larva. This insect is generally a pest only in Eastern New York. Because adults are visually attracted to apple blossoms, sticky-coated white rectangles that are non-UV-reflecting can be used to monitor adults. In Massachusetts, a spray is recommended at petal fall if more than an average of 6-9 EAS per trap are captured by petal fall in an orchard that received prebloom insecticide, or 4-5 in an orchard that did not receive prebloom insecticide. We do not recommend monitoring for this pest in New York because it is normally controlled by the initial spray applied at petal fall to control the plum curculio.


By: Art Agnello, Entomology, Geneva

Deb Breth reported some high populations of eriophyids (rust mites) on fruit cluster leaves in a Wayne Co. peach planting, and, not having seen anything like this in our region before, I put the question to some of our colleagues in Michigan and Virginia. Apparently, these fit the description of peach silver mite (PSM), Aculus cornutus. The following is taken from a Mid-Atlantic States orchard monitoring guide due out next month, courtesy of Doug Pfeiffer at VPI:

A check of the tree-fruit miticides reveals that Omite 30WP has a label for this pest on peaches, at a rate of 5-15 lb/acre. Presumably, a petal fall application should be sufficient to remedy the problem.


A new fact sheet on predatory mites, published by the New York State IPM Program, is now available. The fact sheet gives physical descriptions (with photographs) and describes the biology, effectiveness as biocontrol agents, and management of the three most important predator mite species in New York State: Typhlodromus pyri, Amblyseius fallacis, and Zetzellia mali. It is available from Cornell Media Services in Ithaca (Resource Center-GP, 7 Business and Technololgy Park, Cornell University, Ithaca, NY 14850. Fax: 607-255-9946) for $1.20 per copy. Quantity discounts are available. Request Insect Identification Sheet No. I-23.

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
Editors: A. Agnello, D. Kain
Dept. of Entomology, NYSAES
Geneva, NY 14456-0462
Phone: 315-787-2341 FAX:315-787-2326

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