CHERRY, CONTROL OF TWO SPOTTED SPIDER MITE AND EUROPEAN RED MITE, 2003

Abstract

This study was established to screen new materials and rates of miticides for control of TSSM and ERM in tart cherries. The trial was conducted at the Northwest Michigan Horticulture Research Station in Traverse City, MI. Three-tree plots were established in a mature block of Montmorency tart cherry trees, and treatments then assigned in a RCB design with four replications. The test materials were applied at threshold on 7 Aug with an FMC 1229 airblast sprayer calibrated to deliver 60 gpa. Random samples were collected from four areas of the orchard on a weekly basis to monitor TSSM populations for action threshold levels of seven to ten motiles per leaf. A pre-application count of TSSM and ERM motiles was conducted on 6 Aug, and subsequent post-application evaluations were made on 11 Aug (4 DAT), 18 Aug (11 DAT), 25 Aug (18 DAT), 2 Sep (26 DAT), and 8 Sep (32 DAT). On each date, 50 randomly selected leaves were picked from the middle tree of each replicate, brought back to the lab, and passed through a mite-brushing machine. Motile forms of TSSM and ERM were then counted with the aid of a stereo microscope. Since ERM populations did not develop in this trial, no data are reported. All mite data are reported as the mean number of mites per leaf and were analyzed using ANOVA and means separation by LSD at P = 0.05.