Citrus Thrips Insecticide Trial 2, 2017

A field trial was conducted in a 25-yr-old ‘Parent’ navel orange orchard at the Lindcove Research and Extension Center, Exeter, California to compare the efficacy of various insecticides to protect fruit from citrus thrips rind scarring. Insecticides were applied at petal fall, on 25 Apr 2017, and all trees received a second application of the same or a different insecticide on 9 May. Treatments were diluted in 200 gal of water per acre and applied in an RCB design to four blocks of four-tree plots using a 100-gal high pressure D30 diaphragm pump sprayer with mechanical agitation and a hand wand with a D6 nozzle. Treatments were applied using 250 psi and combined with 0.50% Omni 6E oil. All outside fruit within reach were evaluated the week of 2 Aug 2017 and rated 0, 1–2 (slight), and 3–4 (severe) for the level of thrips scarring, and the mean % total fruit scared and the mean % severely scarred fruit were calculated. Treatment means were compared using ANOVA and means separated using Fisher’s LSD (P = 0.05) after arcsine (squareroot(x)) transformation of the proportions.

The untreated control trees had 17.8% citrus thrips-scarred fruit and 2.7% severely scarred fruit (Table 1). The mean number of fruit examined ranged from 23.2 to 33.1 per tree. The Delegate treatment significantly reduced the percentage of total fruit scarred and all three treatments reduced the percentage of severely scarred fruit that would be downgraded in the packinghouse.

This research was supported by a grant from the Citrus Research Board and industry gifts of pesticide and research funding.