APPLE: Malus domestica Borkhausen, 'Red Delicious' MITE FLARING POTENTIAL AND EFFECTS ON BENEFICIALS OF VARIOUS COMPOUNDS, 2003

The objective of this study was to determine the potential for several new CM products to flare ERM populations, especially those in the neonicotinoid class, by comparing them to other CM insecticides from the organophosphate, carbamate and pyrethroid classes. Treatment timing was designed to simulate application for CM control. The test materials were applied to 16-yr-old 'Red Delicious' apple trees at the Trevor Nichols Research Complex in Fennville, MI (Violet Block) with an FMC 1029 airblast sprayer calibrated to deliver 50 gpa at 2.5 mph. Two-tree plots were arranged in a RCB design and replicated 4 times. Tree spacing was 10 × 21 ft, with at least two buffer trees and one buffer row separating all plots. Sevin XLR (1.0 pt/acre) was applied to the entire orchard on 1 Jun for apple thinning. All treatments were initiated at CM egg hatch on 16 Jun and a second application was applied 14 d later on 30 Jun. A third application was put on at second generation CM egg hatch on 14 Aug. A pre-application mite evaluation was conducted on 9 Jun, and subsequent post-application evaluations were conducted on 30 Jun, 14 Jul, 28 Jul, 14 Aug, and 28 Aug by picking 50 randomly selected leaves from each replicate for a total of 200 leaves per treatment. Mites and eggs were removed with a mite-brushing machine and counted under a stereomicroscope. The number of ERM eggs and motiles were recorded, as well as motiles of the predatory mites ZM and AF. Foliar mite data are reported as the mean number of mites or eggs per leaf. An evaluation was conducted on 8 Oct to quantify the effects of the treatments on the number of overwintering eggs deposited on limbs. Ten subsamples, each consisting of a 6-inch section of branch that included the basal node of the current year's growth, were collected from each plot and taken back to the lab. The limbs were marked 0.5-inch on either side of the basal node on the new growth, and the mean diameter of the limb recorded. All ERM eggs between the marks were counted, and the mean number of eggs per cm2 was calculated. Data were analyzed using ANOVA and means separated by LSD (P ≤ 0.05).