June 23, 2003 Volume 12 No. 15 Update on Pest Management and Crop Development
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Upcoming Pest Events |
Trap Catches | Pest Focus | Insects
Upcoming Pest Events | Trap Catches | Pest Focus | Insects
Upcoming Pest Events | Trap Catches | Pest Focus | Insects
Geneva: 1st Obliquebanded Leafroller moths caught 6/17. Spotted Tentiform Leafminer 2nd flight beginning.
Upcoming Pest Events | Trap Catches | Pest Focus | Insects
Geneva Predictions: Roundheaded Appletree Borer Codling Moth Lesser Appleworm Obliquebanded Leafroller Oriental Fruit Moth Redbanded Leafroller San Jose Scale Spotted Tentiform Leafminer Highland Predictions: Roundheaded Appletree Borer Codling Moth Lesser Appleworm Obliquebanded Leafroller Oriental Fruit Moth Redbanded Leafroller San Jose Scale Spotted Tentiform Leafminer
Plum Curculio. Accumulated heat units need to reach 340 (base 50F) from petal fall before the predicted end of the immigration of ovipositing females. Most sites should be well past this mark after the steamy temperatures predicted for this week. Our numbers as of today, June 23:
Oriental Fruit Moth. Applications against the 1st brood should all be finished by now. The sprays against the 2nd brood aren't advised until we get to 1150 (peaches) and 1450 (apples) DD (base 45F) from biofix; our numbers as of today, June 23:
Codling Moth. All sites are at (or nearly so) the 250 DD (base 50F) first spray date, but we're assuming that the necessary plum curculio applications will cover this timing. We currently have:
(Art Agnello & Harvey Reissig, Entomology, Geneva) Green Aphids: Apple aphid, Aphis pomi De Geer, Spirea aphid, Aphis spiraecola Patch Although small numbers of these aphids may be present on trees early in the season, populations generally start to increase in mid- to late June. This trend has been delayed somewhat by the cool spring weather this year, but our early plentiful rains and predicted heat should soon provoke a respectable amount of the succulent terminal growth much favored by these insects. Large numbers of both species may build up on growing terminals on apple trees during summer. Both species are apparently common during the summer in most N.Y. orchards, although no extensive surveys have been done to compare their relative abundance in different production areas throughout the season. Nymphs and adults of both species suck sap from growing terminals and water sprouts. High populations cause leaves to curl and may stunt shoot growth on young trees. Aphids excrete large amounts of honeydew, which collects on fruit and foliage. Sooty mold fungi that develop on honeydew cause the fruit to turn black, reducing its quality. Aphids should be sampled several times throughout this season starting in late June. Inspect 10 rapidly growing terminals from each of 5 trees throughout the orchard. Record the percentage of infested terminals. No formal studies have been done to develop an economic threshold for aphids in N.Y. orchards. Currently, treatment is recommended if 30% of the terminals are infested with either species of aphid, or at 50% terminal infestation and less than 20% of the terminals with predators. An alternative threshold is given as 10% of the fruits exhibiting either aphids or honeydew. The larvae of syrphid (hoverflies) and cecidomyiid flies (midges) prey on aphids throughout the summer. These predators complete about three generations during the summer. Most insecticides are somewhat toxic to these two predators, and they usually cannot build up sufficient numbers to control aphids adequately in regularly sprayed orchards. Check Tables 5 (p. 54) and 12 (p. 61) in the Recommends for toxicity ratings of common spray materials. Both aphids are resistant to most organophosphates, but materials in other chemical classes control these pests effectively, including Asana, Avaunt, Danitol, Dimethoate, Lannate, Provado, Thiodan, Vydate and Warrior. Woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann) WAA colonizes both aboveground parts of the apple tree and the roots and commonly overwinters on the roots. In the spring, nymphs crawl up on apple trees from the roots to initiate aerial colonies. Most nymphs are born alive to unmated females on apple trees during the summer. Colonies initially build up on the inside of the canopy on sites such as wounds or pruning scars and later become numerous in the outer portion of the tree canopy, usually during late July to early August. Aerial colonies occur most frequently on succulent tissue such as the current season's growth, water sprouts, unhealed pruning wounds, or cankers. Heavy infestations cause honeydew and sooty mold on the fruit and galls on the plant parts. Severe root infestations can stunt or kill young trees but usually do not damage mature trees. Large numbers of colonies on trees may leave sooty mold on the fruit, which annoys pickers because red sticky residues from crushed WAA colonies may accumulate on their hands and clothing. During July, water sprouts, pruning wounds, and scars on the inside of the tree canopy should be examined for WAA nymphs. By the end of the month, new growth around the outside of the canopy should be examined for WAA colonies. No economic threshold has been determined for treatment of WAA. Aphelinus mali, a tiny wasp, frequently parasitizes WAA but is very susceptible to insecticides and thus does not provide adequate control in regularly sprayed commercial orchards. Different rootstocks vary in their susceptibility to WAA. The following resistant rootstocks are the only means of controlling underground infestations of WAA on apple roots: MM.106, MM.111, and Robusta. WAA is difficult to control with insecticides because of its waxy outer covering and tendency to form dense colonies that are impenetrable to sprays. WAA is resistant to the commonly used organophosphates, but other insecticides are effective against WAA, including Diazinon and Thiodan.
(Dick Straub, Entomology, Highland) Effects on Phytoseiids of Non-OP Alternatives Applied at Apple Maggot Timing, 2002 Preliminary assessments of mite populations in a commercial block of Red Delicious revealed extremely high levels of the phytoseid predator mite,Amblyseius fallacis (AMB). Our objectives during 2002 were to evaluate conventional non-OP insecticides (Sevin XLR, Danitol, and Asana compared with Guthion and an untreated check) for effects on European red mite (ERM) and AMB when used on a timing schedule for control of apple maggot. Secondarily, because the maximum use rate allowed for Danitol in NY is 10.7 oz/acre (remainder of civilized world can use at 21.3 oz/acre), we evaluated the reduced rate for efficacy against ERM. Treatments were applied once (August 24) by airblast sprayer to single-tree plots replicated four times in a randomized complete block design. Phytophagous and predacious mite populations were evaluated by sampling 25 leaves from each plot on 24 Aug (pre-treatment count), and subsequently at 10d and 28d post-application.
Pre-treatment count numbers of ERM were low, averaging 0.5 mites/leaf (Table 1). Pre-treatment count numbers of AMB however, were quite high, averaging 1.3/leaf. Because numbers of AMB inexplicably decreased in the untreated check at 10d post-application, data were corrected for untreated mortality. All insecticide treatments, including Guthion, significantly reduced numbers of AMB. As expected, the selected non-OP insecticides were quite toxic to the predator. At 28d post-application however, AMB had recovered in the Guthion treatment, and this was reflected in correspondingly low ERM numbers. In the Sevin and Asana treatments, AMB did not recover, and ERM rapidly multiplied to exceed the August treatment threshold of 7.5 mites/leaf. Moreover, AMB did not recover in the Danitol treatment, but ERM remained low because this insecticide has miticidal activity. All non-OP alternatives evaluated were variously toxic to AMB, and even a single application was sufficient to flare ERM. Danitol, however, although toxic to AMB, has low potential to flare ERM because of its innate toxicity to the pest. Guthion, although initially toxic to AMB, allowed the predators to recover sufficiently to provide biological control of ERM at 28 d post-application. Danitol was effective against ERM at the somewhat reduced rate mandated in NY. Table 1. Non-OP alternatives applied at apple maggot timing - effects on phytoseiids and European red mite, Stone Ridge, NY - 2002.
This material is based upon work supported by Smith Lever funds from the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture. 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 Online at <http://www.nysaes.cornell.edu/ent/scaffolds/>
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