Citrus Thrips Insecticide Trial, 2019

A field trial was conducted in a 17-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 just after petal fall on 1 or 2 May and all trees received a second application of the same or a different insecticide on 14 or 15 May. Treatments were applied at 250 psi in 200 gpa 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. All treatments were combined with 0.50% Omni 6E oil. All outside fruit within reach were evaluated the week of 12 Aug and rated 0, 1–2 (slight), or 3–4 (severe) levels of thrips scarring. The mean number of fruit per tree sampled, the mean % total thrips scarred fruit and the mean % severely scarred fruit per tree were compared between treatments using a one-way ANOVA after testing for an NS block effect. Treatment means were separated using Fisher’s protected least significance different test LSD (P = 0.05) after acrsine(squareroot(x)) transformation of the proportions and log₁₀(x + 1) transformation of the mean sampled fruit.

The untreated check trees had 31.1% citrus thrips-scarred fruit and 12.9% severely scarred fruit (Table 1). Two treatments of Delegate did not significantly reduce thrips severe scarring below the untreated control but all other treatments had a significant effect. The most effective treatments, reducing severe scarring below 2%, were Delegate followed by Minecto Pro, Delegate followed by Exirel, Exirel applied twice, PQZ followed by Minecto Pro and Minecto Pro applied twice.1

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