CONTROL OF EUROPEAN RED MITES ON APPLE, 2005

This trial was designed to determine the efficacy of different rates and timings for various new miticides. Two-tree plots were established in an 18 yr old ‘Red Delicious’ apple block (Brown Block) at the Trevor Nichols Research Complex in Fennville, MI and treatments arranged in a RCB design with four replications. Tree spacing was 18 × 20 ft, with a minimum of one buffer tree and one buffer row separating all plots. Regular foliar maintenance applications of Nova, Dithane, Penncozeb, Flint, Asana XL, Vangard, Ziram, Sevin, Guthion, and Mora-Leaf 20-20-20 were applied separately to the entire orchard. In addition, Glyphomax Plus and Sinbar were banded under the trees for weed control. Apollo and Agri-Mek treatments were applied on 23 May (PF+7 d) and the rest of the treatments were initiated at an ERM action threshold of 2-3 motiles per leaf on 3 Jun. All treatments were applied with an FMC 1029 tractor-mounted airblast sprayer calibrated to deliver 100 gpa at 2.5 mph. Evaluations of all plots were conducted on 2 Jun (prior to threshold application), 9 Jun (6 d after threshold application, DAT), 16 Jun (13 DAT), 23 Jun (20 DAT), 30 Jun (27 DAT), 7 Jul (34 DAT), 13 Jul (40 DAT), and 21 Jul (48 DAT), and 1 Aug (61 DAT), by picking 50 randomly selected leaves from each replicate for a total of 200 leaves per treatment. Mites and eggs were removed with a mitebrushing machine and counted under a stereo microscope. Data collected on 1 Aug and later dates are not included as all plots continued to decline due to an extended drought. All mite data are reported as the mean number of mites or eggs per leaf (Tables 1 and 2, respectively), and percentage control (Table 3). Mean percentage control was calculated for evaluations conducted 3, 5 and 7 wk after threshold application using the Henderson-Tilton formula; % control = [1 – ((n control plot before treatment * n treated plot after )/( n control plot after treatment * n treated plot before ))]*100, and all data were analyzed using ANOVA and means separation by Duncan’s New MRT(P = 0.05).