Full-season insecticide management programs for the control of Colorado potato beetle in Wisconsin potato, 2014 *

The purpose of this experiment was to evaluate various full-season, reduced-risk, insecticide programs designed to manage Colorado potato beetle (CPB) on potatoes in Wisconsin. With developing neoicotinoid insecticide resistance among CPB populations in the potato production areas in Wisconsin, several systemic-based and foliar-based programs were designed to evaluate their effectiveness on managing the CPB on potato. This experiment was conducted in 2014 on a loamy sand soil at Hancock Agricultural Research station (HAES) located 1.1 mile (1.8 km) southwest of Hancock, WI. Potato, Solanum tuberosum cv. “Russet Burbank,” seed pieces were planted on 2 May. Plants were spaced 12 inches apart within rows and rows were spaced 3 feet apart. The 8-row plots were 24 feet in width by 40 feet in length, for a total of 0.025 acres/plot. Replicates were separated by a 5-feet border of bare ground. Three replicates of 15 full-season insecticide programs were arranged in a randomized complete block (RCB) design. Systemic insecticides were applied in-furrow at planting (2 May for treatments 1–6). The first application of Rimon (treatment 7) was made on 19 June. The first foliar insecticide applications were applied after peak egg hatch and prior to large larval population development (27 June, for treatments 7–12). Subsequent applications were made on 3 July (for treatments 3–6) and 10 July (for treatments 2, 3, and 9–12). Second-generation CPB foliar applications were made to treatments 1, 2, 7, 8, 11, and 12 on 30 July. Treatment information is available in Table 1 . All in-furrow treatments were applied at 11.0 gpa on 2 May using a two nozzle boom equipped with Tee Jet XR8001 flat fan spray nozzles powered by a CO ₂ backpack sprayer at 30 psi. Furrows were cut using a commercial potato planter without closing discs attached. Immediately after the in-furrow treatments were applied and all seed piece treatments were placed in open furrows, all seed were covered by hilling. Foliar insecticides were applied using a CO ₂ pressurized sprayer with a 24-feet boom operating at 30 psi delivering 20 gpa through 16 Tee Jet XR8002XR flat fan nozzles spaced 18 inches apart while travelling at 4.0 ft/s The efficacy of treatments was assessed by counting the number of egg masses, small larvae, and large larvae per plant on 10 randomly selected plants in each plot. Percent defoliation (% DF) ratings were taken by visual observation of the entire plot. Potato leafhopper (PLH), Empoasca fabae, efficacy was assessed by counting the number of adults collected from 15 sweep net samples in each plot. Aphid and PLH nymph populations were surveyed by visual assessment of 25 leaves per plot. Insect counts occurred on several dates throughout the summer, and reported means were averaged across those dates ( Tables 2 and 3 ). Insect count averages reflect time periods during the summer when specific life stages peaked in the plots. Yield and quality data were collected after harvest (18 September) ( Table 4 ). Data sets were analyzed using analysis of variance, and means were compared using a Fisher’s protected least significant difference mean separation test ( P  = 0.05). No signs of phytotoxicity were observed among treatments.

Author notes