June 9, 2003 Volume 12 No. 13 Update on Pest Management and Crop Development
Geneva: San Jose scale trap catch increasing.
Highland: White Apple Leafhopper and Rose Leafhopper
moving into apple.
Roundheaded Appletree Borer
Oriental Fruit Moth
San Jose Scale
Spotted Tentiform Leafminer
Plum Curculio. Heat units are finally beginning to build, and the forecast calls for highs in the upper 70's this week; however, this is definitely one of those seasons when the egg-laying period promises to be prolonged, so growers will need to keep their fruit protected. Our numbers as of today:
Oriental Fruit Moth. The second application against the first brood in both peaches and apples should be applied at approximately 350-375 DD (base 45F) from biofix:
Codling Moth. These accumulations are also still somewhat behind, but this first brood will likely be taken care of by curculio sprays in most locations. With 250 DD (base 50F) as a first spray date, we currently have:
Obliquebanded leafroller moths have yet to start flying in both the Hudson Valley and in Geneva, but with a week of more seasonal temperatures forecast, we may eventually get back onto a nearly normal schedule for insect activity by mid-month. First hatch is generally assumed to occur from about 300-360 DD (base 43F) after the flight starts, so we'll start updating you each week with values for Highland and Geneva once things get rolling. With some improved pesticide tools now available to NY growers, OBLR management has not appeared to be as much of a challenge recently as it has been in past years, although this pest has not faded entirely into obscurity, and many of the old problem orchards can still be counted on for a reality check if we start to get complacent. Accordingly, a brief synopsis of last year's research efficacy trials might be in order.
Pesticide control programs for the first summer brood of OBLR were conducted in a Wayne Co. orchard in 2002 containing 'Jonagold' and 'Fortune' varieties. Plots were rectangles of eight adjacent rows (approx. 0.25 A) with 6-8 trees in each row. Treatment blocks along with untreated check plots were arranged in a RCB design and replicated twice so that an equal distribution of both varieties were represented in each replicate. Treatments were applied based on estimated DD accumulations (base temp = 43F) after the beginning of the summer flight of adults on 11 Jun. One application was made after an accumulation of 300 DD (estimated first egg hatch) on 25 Jun, while the rest of the treatments were applied at 360 DD (estimated mid-egg hatch) on 1 Jul. These sprays were then reapplied at 14-day intervals from the first application date (10 Jul and 24 Jul for the 300 DD plot and 16 Jul for the 360 DD plots).
The early application (300 DD) consisted of Intrepid 2F (12.0 oz/A) plus Latron B 1956 (16.0 oz/100), and the remainder of the treatments (360 DD) were: Deliver (8.0 oz/A), Dipel DF (1.5 lb./A), Spintor 2SC (5.0 oz/A) applied with LI-700 (16.0 oz/100), Danitol 2.4EC (10.7 oz/A) and an untreated check plot. Initial fruit damage from the summer generation of OBLR was estimated on 26 Jul by inspecting 300 fruits on trees from the center of each plot. Damage was assessed as present or absent, regardless of severity. Harvest evaluations were conducted on 28 Aug by randomly selecting 200 fruits from the center trees within each plot and inspecting them for damage. Fruit injury was classified on the USDA scale of Fancy, #1, or Cull. Data then was subjected to an analysis of variance, and means were separated using Fisher's Protected LSD Test (P<0.05). Data was transformed Arcsin (Sqrt X) prior to analysis.
Pressure from OBLR was relatively low in 2002 compared with past years, and fruit damage levels among the treatments and check plots were generally not statistically different. Fruit damage was considerably low in all of the treatments and the check plots at harvest and the relative effectiveness of treatments was different from that observed during the summer. Treatment rankings varied among the three levels of grading. However, the untreated check plots had the highest percentages of damage in all of the three grades. At harvest, Deliver, Spintor, and Intrepid were the only three treatments that had significanly less total fruit damage than that in the untreated check. Although various Bt products have been tested in NY against OBLR in previous years, Deliver is one of the few materials that has been more effective in preventing damage than the standard Bt product, Dipel, although the differences between these two products is not statistically significant. Danitol was less effective than any of the other treatments in protecting fruit, and damage in these plots at harvest was not significantly lower than that in the untreated checks. The relative ineffectiveness of this material may have been due to a buildup of resistance by OBLR populations within this region from previous usage of various synthetic pyrethroids.
Table 1. Comparison of insecticides against obliquebanded leafroller, 2002
Means within a column followed by the same letter are not significantly different (Fisher's Protected LSD Test, P 0.05). Data transformed arcsine (sqrt[x]) prior to analysis.
On Thursday, 5 June, the NYS DEC granted a registration for the use of Isomate-LPTB to control lesser peachtree borer and ("greater") peachtree borer in a wide range of stone fruits in NY. The standard rate for control of lesser peach tree borer is 100 ties per acre. If the ties are applied at a higher rate, both species of borer can be controlled by the application of the LPTB ties. Now would be the proper timing for application because we have just caught the first LPTB moth in Geneva today; PTB flight is expected in a few weeks. This product performed very well in NY field trials, and is a recommended alternative to pesticide sprays of trunks and scaffold branches.