Understanding the Efficacy of Hexythiazox Against Twospotted Spider Mites in Strawberry, 2022

Abstract

Twospotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae), is a serious pest of strawberry, Fragaria x ananassa (Rosaceae) in Florida. Management of T. urticae is challenging with very few effective miticides available for controlling the pest. The objective of the study was to understand the efficacy of miticides, hexythiazox (Onager Optek) alone, and in combination with abamectin (Agri-Mek SC), compared with cyflumetofen (Nealta), abamectin (Agri-Mek SC), and untreated control against T. urticae in strawberries. On 8 October 2021, bare root strawberry cultivar, ‘Florida Brilliance’, was planted on 32-ft-long strawberry beds with a plot size of 20 plants per plot at the Gulf Coast Research and Education Center (GCREC), Wimauma, University of Florida. Treatments were initiated in February 2022, once the natural T. urticae populations had built up significantly in the experimental plots. The details of miticide treatments and rates are shown in Table 1. Four replicates of each treatment was assigned to four strawberry beds in a randomized complete block design. All products were tank mixed with the surfactant LI700 at the rate of 0.125% (v/v). Miticide treatments were applied on 16 February 2022, with a backpack sprayer calibrated to 40 gallons per acre and at 40 PSI. Five random strawberry plants in each plot were sampled to assess T. urticae population. Sampling was conducted on a day before the application and then at 3, 10, and 20 d after treatment (DAT). Tissue samples consisting of strawberry trifoliates, and fruits were brought to the Entomology laboratory at the GCREC and washed with 70% ethanol for counting T. urticae eggs, nymphs, and adults under stereomicroscope.