July 21, 2003 Volume 12 No. 19 Update on Pest Management and Crop Development
Oriental Fruit Moth
Spotted Tentiform Leafminer
Oriental Fruit Moth
Spotted Tentiform Leafminer
Oriental Fruit Moth. Despite the fact that the 2nd brood flight started in Geneva on 7/3, and in Harvey Reissig's research plots in Williamson on 7/10, catches in many areas (including some problem blocks) have been extremely variable. The provisional PA model suggests that the 50% hatch point should occur somewhere around 1450 DD-45, and we're approaching that in the most advanced sites. However, our strangely delayed field catches have everybody a bit confused as to what's happening (not to mention the difference between apples and peaches). Therefore, we're going with the evidence of the several sites showing the highest catch numbers, and are recommending that apple orchards with a history of high pressure start getting their first spray against the 2nd brood sometime this week if they haven't already received it. For the record, our numbers from the season's first biofix as of 7/21 are:
Codling Moth. The first application against the 2nd brood of this species is not advised until 1260 DD (base 50°F) after the season's first biofix, and we're still a good 1-2 weeks away from that mark in most sites.
Obliquebanded Leafroller. Sites on a Spintor program should be approaching their 2nd application against the first summer brood, which should be near about the 90% hatch point this week.
(Art Agnello, Entomology, Geneva)
Someone recently remarked to me how it seems to be kind of a slow season for insect problems so far, to which I agreed only as much as a natural distrust of such impressions would allow me, for fear of awakening some bad mojo we'd have to fight off for the final six or so weeks of the season. To be certain, a few of our perennial summer pests are on the job, so here's a brief rundown of what to keep in mind:
Oriental Fruit Moth & Co.
The second flight of this peach (and apple) pest started at the beginning of July, and we are now within the window to begin the second round of sprays. We recommend Asana in two applications, spaced 14 days apart. If you haven't begun treating for this generation of OFM, this week is still not too late to start. Refer to the discussion of OFM control timing in the Model Building article for more information. Shoot-flagging injury from the first brood larvae is evident in Niagara Co. orchards by now, but those orchards relying on pheromone mating disruption seem to be holding their own. A little attention to orchard weed management now can help minimize later season catfacing injury.
A few orchards we have seen are in trouble from European red mites so far, but also keep in mind the potential for two-spotted mite, which can reach alarming levels in a hurry. Inspect your leaves using the 5 mite/leaf form in the Recommends, and be aware that two-spot populations increase more quickly than ERM, so be conservative in your interpretations. Acramite tends to be the most effective material against TSSM and Pyramite works better against red mites than it does on TSSM, but the main advice is to get out there and look at your foliage.
We have been hearing reports of building infestations of this nuisance pest in orchards recently. The woolly apple aphid (WAA), Eriosoma lanigerum, 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. Their presence now can serve as an indication of potential trouble spots later on.
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.
Water sprouts, pruning wounds, and scars on the inside of the tree canopy should be examined for WAA nymphs, and 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 (particularly pyrethroids) and thus does not provide adequate control in regularly sprayed commercial orchards. Different rootstocks vary in their susceptibility to WAA. Resistant rootstocks such as MM.106, MM.111, and Robusta are the only means of controlling underground infestations of WAA on apple roots; M.9 rootstock is very susceptible. WAA is difficult to control with insecticides because of its waxy outer covering and tendency to form dense colonies that are impenetrable to sprays. This insect is resistant to many commonly used materials, but insecticides that are effective include Diazinon, Provado, Actara (if you haven't already used the single application allowed per season), Thiodan, and dimethoate. Use of a wetting agent will improve penetration of the woolly masses and, therefore, control efficacy.
This perennial pest overwinters as a partially grown grub in the soil below the frost line. In the spring the grub resumes feeding, primarily on the roots of grasses, and then pupates near the soil surface. Adults begin to emerge during the first week of July in upstate N.Y., and if you have looked at any roses lately, you know that they are right on schedule this year. The adults fly to any of 300 species of trees and shrubs to feed; upon emergence, they usually feed on the foliage and flowers of low-growing plants such as roses, grapes, and shrubs, and later on tree foliage. On tree leaves, beetles devour the tissue between the veins, leaving a lacelike skeleton. Severely injured leaves turn brown and often drop. Adults are most active during the warmest parts of the day and prefer to feed on plants that are fully exposed to the sun.
Although damage to peaches is most commonly noted in our area, the fruits of apple, cherry, peach and plum trees may also be attacked. Fruits that mature before the beetles are abundant, such as cherries, may escape injury. Ripening or diseased fruit is particularly attractive to the beetles. Pheromone traps are available and can be hung in the orchard in early July to detect the beetles' presence; these products are generally not effective at trapping out the beetles. Fruit and foliage may be protected from damage by spraying an insecticide such as Sevin, or Provado (not labelled in peaches this year, remember) when the first beetles appear.
(Information adapted from: Johnson, W.T. & H.H. Lyon. 1988. Insects that feed on trees and shrubs. Cornell Univ. Press.; and Howitt, A.H. 1993. Common tree fruit pests. Mich. State. Univ. Ext. NCR 63.)
Catches have not been terribly high yet, but they are beginning to show up in our statewide research blocks. If you aren't monitoring in specific orchards and haven't yet applied a protective spray against AM (and aren't using Spintor for OBLR), prudence would suggest a bit of attention to this insect. Hanging a few volatile-baited sphere traps on the edge of susceptible plantings can provide a world of insight on when (and whether) immigrating flies are posing a threat. Growers on a Spintor program should be somewhere between the first and second spray of this material for leafrollers, which will provide protection against moderate AM pressure.
This formerly rare pest has been known recently to cause damage to nectarines and peaches in the Hudson Valley. Originally limited to western North America, this is now a cosmopolitan species that is a key pest in the greenhouse production of flowers and vegetables. Apparently, drought conditions and high temperatures encourage damaging populations that can affect stone fruit crops, particularly nectarines and peaches. The following information is taken from the PA Tree Fruit Production Guide: "...just prior to and during harvest,...adults move from alternate weed or crop hosts to fruit. [They] feed on the fruit surface in protected sites, such as in the stem end, the suture, under leaves and branches, and between fruit. Feeding ...results in silver stipling or patches. Silvering injury is particularly obvious on highly colored varieties. Because Lannate has a short preharvest interval (4 days), it can be used to control thrips during harvest." Also, SpinTor can be used within 14 days of harvest. An application after the first harvest may prevent subsequent losses; however, an additional application may be needed if thrips pressure is severe.