Control of stone fruit borers in tart cherry, 2022

A trial was conducted to evaluate the efficacy of different insecticides belonging to different insecticide classes against various species included in the stone fruit tree borer complex (American plum borer, lesser peach tree borer, and peach tree borer). The trial was conducted at the Michigan State University (MSU) West Central MI Research and Extension Center in Hart, MI (43° 47ʹ 8.5986ʹ N, 86° 8ʹ 21.3282ʹ W) in 2022 by spraying single-tree plots of tart cherry (Prunus cerasus, cv. ‘Montmorency’) in a complete randomized block design with 4 replicates. Insecticide applications were done on 9 Jun and 7 Jul 2022 using formulated products (Table 1). Before insecticide applications, tart cherry tree trunks were artificially wounded using a hatchet to emulate wounds by mechanical shakers in industry scale farm on all 4 cardinal directions immediately before each insecticide application totaling 8 artificial wounds on each tree. Insecticide applications were applied using a County Line 15-gallon Spot Sprayer (Tractor Supply Co., Brentwood, Tennessee) until adequate coverage was achieved on tree trunks.

Field evaluation for damage severity was done the following year on 13 Oct 2023 by scoring based on frass produced on each artificial wound made the previous year. Severity scoring followed these criteria: 0: no fresh frass detected on artificial wounds; 1: >0%–5% of artificial wound area covered with fresh frass; 2: >5%–20% of artificial wound area covered with fresh frass; 3: >20%–50% of artificial wound area covered with fresh frass; 4: >50%–70% of artificial wound area covered with fresh frass; 5: >70% of artificial wound area covered with fresh frass. Mean scores were presented and analyzed using Kruskal–Wallis, and a post hoc test was done using the Dunn test at P-value ≤ 0.05. Lorsban 4E and Altacor 35WG were the only treatments that showed significantly reduced severity scores compared to untreated check, while Assail 30SG, Rimon 0.83EC, and Asana XL 0.66EC were not significantly different compared to the untreated check (Table 1).¹

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