Control of Aphids on Potato, 2017

Aphids have the ability to spread viruses; therefore, continued testing of new chemistries and monitoring the efficacy of existing compounds are very important. The experiments were conducted in Presque Isle, ME in 2017. The plots were four-rows wide (12 feet) and 30-ft long. Experiments were replicated four times and arranged in an RCB design. A ten-ft space was left fallow between blocks, and a six-ft space was left fallow between the plots within the blocks. Machine-cut ‘Atlantic’ seed was planted 25 May. A four-row Lockwood (Model 425) planter placed seed in an open furrow every 12 inches, and delivered 14-14-14 fertilizer at the rate of 1,100 lb per acre. The rows were mechanically covered, placing the seed piece approximately 3 inches below the surface. Foliar insecticides were applied 28 Jul and 03 Aug with a modified Century boom sprayer, delivering foliar sprays through eight Turbo Twinjet nozzles per rep at 35-psi pressure and 40 gpa, and boom height 20–24 inches. Tractor speed was 2.8 mph. Blackhawk (2.0 oz/acre) was applied to all treatments on 08 Jul to prevent excessive defoliation by Colorado potato beetles. The crop was treated with Bravo ZN at 5- to 7-day intervals based on recommendations from the University of Maine Cooperative Extension throughout the season for late blight control. Aphid numbers (by species) were counted weekly on one top, one middle, and one bottom leaves of 20 plants selected at random in the middle two rows of each plot. ANOVA were conducted following transformation of the data using log₁₀ (X + 1) 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 Caribou gravely loam, pH 6.0. The total monthly rainfall for June, July, and August (through 22 August, which was the last day of the trial) was, respectively, 3.86", 2.36", and 1.81" and the average mean temperature was 60°F, 65°F, and 64°F.

A total of 1,263 aphids were counted on the experimental plots throughout the season. Of those, 39% were buckthorn aphids, 30% were green peach aphids, and 31% were potato aphids. The purpose of the first experiment (Table 1) was to compare foliar applications of BAS 440 and Movento HL with Sivanto Prime and Movento 240 as the industry standards. Aphid populations were low until the end of August. No significant differences were found during the first four sample dates. All treatments during the 22-Aug evaluation date controlled aphids compared with the untreated check. The purpose of the second foliar experiment (Table 2) was to compare how Minecto Pro applied at two different rates compared with several industry standards. Aphid populations were low until the end of August. Minecto Pro had little effect on aphids when compared with the industry standards. No phytotoxicity was observed with any of the treatments.

This research was supported by industry gifts of pesticide products and money.