Western flower thrips control with neonicotinoid-treated lettuce seed, 2022 Open Access

The objective of this trial was to evaluate the efficacy of clothianidin (NipsIt; Valent USA) seed treatment to control western flower thrips (WFT) in lettuce under desert growing conditions. Commercially treated with clothianidin and untreated romaine lettuce ‘Del Sol’ seed was direct seeded on 23 Feb 2022 at the Yuma Agricultural into beds on 42-inch centers with 2 seed lines per bed. All seeds were planted at a 2-inch spacing. Stand establishment was achieved using overhead sprinklers and irrigated with furrow irrigation thereafter. Plots were 2 beds wide by 35 ft long and bordered by 2 untreated beds. Four replications of each treatment were arranged in an RCB design. No other insecticides were applied during the trial.

WFT numbers were estimated using a whole plant wash method. On each sampling date, 5 plants on each plot were randomly selected and removed from the soil at ground level. Samples were processed using a washing technique and the number of adults and larvae in each sample were counted using magnification. Because of heterogeneity of mean variances, data were transformed using a log10 (x + 1) function before analysis and subjected to ANOVA, and means were compared using Turkey’s honestly significant difference test (α = 0.05). Means from nontransformed data are presented in the tables.

WFT numbers were low to moderate in this trial. There were no significant differences among treatments for numbers of WFT adults (Table 1) and larvae (Table 2) on any sample date. No phytotoxicity was observed.

Funding

This research was supported by a grant from the Arizona Iceberg Lettuce Research Council.