Registered and experimental foliar insecticides to control Colorado potato beetle and potato leafhopper in potato, 2014 * Open Access

The objective of this experiment was to assess the efficacy of foliar insecticides applied to control insect pests of potato. The trial consisted of 30 main effect treatments arranged in a randomized complete block (RCB) design with four experimental replicates. Potato was machine planted on 22 April 2014 at the Hancock Agricultural Research Station in central Wisconsin. Experimental plots consisted of two-row plots measuring 6 ft (1.8 m) in width and 20 ft (6.1 m) in length with unplanted guard rows on each side. Rows were planted on 36-inch row centers (0.9 m) with 12 inches (0.3 m) between plants with 12-ft (3.6 m) alleys separating replications. All foliar treatments were applied at 20 gpa using a four-nozzle, 6-ft (1.8 m) boom equipped with an XRVS 8002 flat fan spray tip powered by a CO ₂ backpack sprayer operating at 30 psi. Foliar treatments were applied twice in succession when 75–90% of the first generation CPB was within the first and second stadia. Foliar applications of novaluron (Rimon 0.83EC) were initiated 11 June, 1 wk earlier than all other treatments. The first foliar application occurred between 10:00 and 11:00 hours on 19 June 2014, and application conditions were recorded as an east wind at 3.5 mph (5.6 kph), 67.6°F (19.8), 88% RH, under partly cloudy skies. A second application occurred on 26 June 2014 between the hours of 10:00 and 11:00. Application conditions were recorded as a southeast wind at 6.0 mph (9.6 kph), 71.3°F (21.84°C), 66.5% RH, under cloudy skies. All plots were maintained according to standard commercial practices. CPB adults, egg masses, small larvae, large larvae as well as PLH adults and nymphs were assessed by counting the number of each life stage on 10 randomly selected plants from the center two rows in each plot. CPB counts occurred five times during June and July. The first set of counts occurred on 23 and 25 June (4 and 6 DAT) after the first application. The second set of counts occurred on 30 June, 7 and 14 July (4, 11, and 18 days after treatment) after the second application. Adult PLH counts were performed on 24 June, and 1, 8, and 15 July count data were log ₁₀ transformed prior to data analysis using analysis of variance. Means were compared using the least significant difference option in an analysis of variance.

Populations of CPB were already established by the first foliar application, as defoliation estimates approached 5% in most plots. Experimental treatments were often significantly different than untreated check in the control of CPB adult, larval, and associated defoliation, although some treatments were more effective at controlling immature CPB ( Table 1 ). Adult PLH pressure was moderate, and the neonicotinoid-containing compounds plus the synthetic pyrethroids provided the most effective control of PLH adults. No evidence of phytotoxicity was observed.

Author notes