Speed-Sprayer Trials for Citrus Thrips Control, 1994

Insecticides were evaluated in 2 fields at the University of California’s Lindcove Field Station near Exeter, California for control of citrus ,thrips. Pesticides were applied with an FMC CP-757 speed-sprayer. In Field 23, different rates and timings of Agri-Mek were evaluated using 125 gpa and outside coverage (achieved by reducing fan speed). In Field 41-42, 5 treatments were compared against an untreated control and were applied similarly. Field 23 was divided into 10 plots and Field 41-42 was divided into 12 plots; treatments were assigned to plots randomly and replicated twice in each field. Each plot was 6 rows wide and 5-8 trees long. In each plot, 10 data trees were chosen from the center 2 rows of the plot, excluding the trees at the end of a row. Citrus thrips infestation due to first and second instars was monitored twice a week for 6 wks after petal fall by examining 5 fruit randomly from each data tree (50 fruit per plot, 100 fruit per treatment in each field). Citrus thrips fruit scarring evaluations were taken in Oct 1994 on all fruit on the exterior of data trees from knee to eye level. Typical scarring levels on outside fruit as sampled in this study are approximately twice as high as percent scarring of fruit sampled from the entire tree (inside fruit are less severely scarred). Scarring was rated as: (a) none, (b) slight (any citrus thrips scarring), or (c) severe (complete ring scar or extensive surface scarring at a level that would cause downgrading of fruit in a commercial operation). Economic scarring levels in a normal year are about 5% severe scars.