Control of Colorado potato beetle on potato by ledprona, 2024

Testing new chemistries and monitoring the efficacy of existing compounds is extremely important because the CPB has the ability to build up resistance to chemicals. The experiment was conducted in Presque Isle, Maine in 2024. The experiment followed an RCB design and treatments were replicated four times. Plots were 4 rows wide (12 ft) and 30 ft long. A 10-ft space was left fallow between blocks and a 6-ft space was left fallow between the plots within the blocks. Machine-cut ‘Reba’ seed was planted on 24 May. A Lockwood (Model 425) pick planter placed seed in an open furrow every 12 inches and delivered 14-14-14 fertilizer at 1,100 lbs per acre. Platinum (2.66 oz/A) was applied in-furrow to treatments 5, 6, 7, and 8 at the time of row closure (24 May) using a custom-built sprayer, a single nozzle per row, 8-inch band at 12 psi pressure at 5 gpa, and 1.5 mph tractor speed. The rows were mechanically covered, placing the seed piece approximately 3 inches below the surface. Foliar applications were applied on 3, 9, and 15 July with a modified Century sprayer, with 8 Turbo Twinjet (TTJ60-11003) nozzles per rep at 40 psi pressure and 20 gpa. The boom height was 18”, and the tractor speed was 4.3 mph. The crop was treated with Bravo Weather Stik based on recommendations from the University of Maine Cooperative Extension throughout the season for late blight control. The numbers of CPB adults and larvae were counted weekly on 10 plants selected randomly from the center 2 rows of each plot. Potato defoliation was quantified by visually estimating the percentage of foliage missing on each plot due to beetle feeding damage. When dates of count and application were the same, counts were made before applications of the insecticide. Data were transformed using log₁₀(X + 1) for insect counts and arcsine square roots for defoliation. ANOVA was conducted, and means were compared using Fisher’s LSD test. Means followed by the same letter do not significantly differ from each other (P > 0.05). The soil is classified as a Caribou Loam, pH 6.3. The total monthly rainfall for Jun, Jul, and Aug was, respectively, 5.18”, 4.58”, and 4.38” and the average temperature was 63.36, 68.59, and 63.85 °F.

This experiment tested the incorporation of Calantha in a season-long spray program in Maine for control of Colorado potato beetles. All treatments reduced Colorado potato beetle abundance and damage compared to the untreated check (Tables 1 and 2). The performance of Calantha was similar to that of other foliar insecticides. Applying Platinum in furrow followed by foliar applications of other insecticides resulted in better control compared to foliar-only programs. Phytotoxicity was not observed following the insecticide treatment applications.¹

Footnotes