Lygus control in carrot grown for seed, 2025

Central Oregon is a globally important production region for hybrid carrot seed, and feeding damage caused by the western tarnished plant bug (Lygus hesperus) during seed fill can reduce seed quality and germination. A small-plot insecticide efficacy trial was conducted to evaluate several insecticides for control of L. hesperus in hybrid carrot seed production. The study was conducted in a commercial hybrid carrot seed field approximately 4 miles north of Madras, OR. Treatments were arranged in a RCB design with 3 replicates. Individual plots consisted of 4 rows of the female parent line (30-inch row spacing) by 50 ft in length. Each replicate was located in a separate bed with a 10-ft bed of male parent plants separating blocks. Treatments were applied shortly after the removal of honeybees used for pollination on 14 Aug 2025, using a CO2-powered backpack sprayer calibrated to deliver 30 gpa through TeeJet XR11004 flat-fan nozzles at 50 psi. All treatments included 0.5% v/v Royal 90 non-ionic surfactant (NIS). All other crop maintenance was provided by the grower using standard commercial carrot seed production practices. Lygus hesperus populations were sampled at 7 and 14 DAT using a standard 15-inch sweep net. Fourteen sweeps were taken between 2 rows across approximately 40 ft in the center of each plot. Each 2-row subsection of the 4-row plot was sampled only once at a single evaluation date. Adult data were not considered because of adult mobility across treatment plots. Collected nymphal stages were frozen and counted under magnification. Data were analyzed using an ANOVA, and treatment means were separated using Tukey’s HSD test (P < 0.05). Orthene provided complete control of L. hesperus nymphs at both evaluation timings, ie 7 and 14 DAT. Among the alternative insecticides evaluated, Transform provided the greatest suppression of L. hesperus and was statistically similar to Orthene. Transform maintained significantly lower nymph densities at both 7 and 14 DAT compared to Beleaf, Brigade, Sivanto Prime, Sedaire, and the untreated check. (Table 1). Beleaf and Brigade provided moderate suppression at 7 DAT, but control declined at 14 DAT. In particular, Brigade plots exhibited a strong population rebound by 14 DAT, resulting in the highest L. hesperus densities followed by Sedaire, Sivanto, and the untreated check. Sivanto and Sedaire showed limited efficacy, with L. hesperus densities similar to those in the untreated check at both evaluation timings (This research was supported in part by Central Oregon Seeds, Inc.). Means within columns followed by the same letter are not significantly different (P < 0.05; Tukey HSD). None declared. None declared.