Speed-Sprayer Trials for Citrus Thrips Control, 1996

Insecticides were evaluated spring, 1996 in Field 41-42 at the University of California’s Lindcove Field Station near Exeter, CA for control of citrus thrips. Pesticides were applied with an FMC CP-267 speed-sprayer pulled behind a tractor. Five treatments were compared against an untreated control using 200 gallons of water per acre and outside coverage (achieved by reducing fan speed). The field was divided into 12 plots; treatments were assigned to plots randomly and were replicated twice in each field; each plot was six rows wide and 5-8 trees long. Ten data trees were chosen from the center two rows of each plot, excluding the trees at the end of a row. Citrus thrips infestation due to first and second instar immatures was monitored after petal fall by examining 10 fruit randomly selected from each data tree (100 fruit per plot, 200 fruit per treatment in each field). Predaceous mite levels were monitored by counting the number of motile mites on 10 leaves picked from 0.5 m inside the canopy. Citrus thrips fruit scarring was evaluated in October, 1995 on all fruit on the exterior of data trees from knee to eye level. 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). Approximately 5% severe scars are normally regarded as economic scarring levels.