Citrus Thrips Insecticide Trial, 2016*

A field trial was conducted in a 24-yr-old ‘Parent’ navel orange orchard at the Lindcove Research and Extension Center, Exeter, California to compare the efficacy of various insecticides on citrus thrips. Insecticides were applied during bloom (5 Apr 2016) or at petal fall (19 and 20 Apr) and most trees received a second application of the same or a different insecticide on 3 or 4 May. Treatments were diluted in 200 gal of water per acre and applied in a RCB design with four blocks of four-tree plots using a 100-gal high pressure D30 diaphragm pump sprayer with mechanical agitation. All treatments were applied with 0.50% Omni 6E oil, except for Bexar and NNI-0101 that were applied with 0.25% Dyne-Amic and Baythroid and Sivanto had no additional adjuvant. All outside fruit within reach (mean 50–86 fruit/tree) were evaluated the week of 18 Jul 2016 and rated 0, 1–2 (slight), 3–4 (severe) for the level of thrips scarring and mean % total fruit scarring and % 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 fruit had 41.3% total thrips scarred fruit and 13.2% severely scarred fruit (Table 1). Sevin and Bexar did not reduce severe citrus thrips scarring significantly below the untreated control levels. Minecto Pro, Exirel, and Delegate treatments applied twice alone and Minecto Pro and Delegate applied as alternations significantly reduced total thrips scarred fruit below 15% and severely scarred fruit below 1.5%. Other treatment combinations produced intermediate results of 15–29% total scarring and 2.5–9% severe scarring. Alternating different chemistries or changing the order of chemistries did not did not appreciably improve control but these strategies are important for pesticide resistance management.

Author notes