Control of Spotted Wing Drosophila in Tart Cherry, 2018

We evaluated the effects of three to five applications of individual insecticides, or insecticides used in rotation, against Spotted Wing Drosophila (SWD) in Tart Cherry. Single-tree plots were established in a 24-yr-old ‘Montmorency’ cherry planting (15 × 20 ft spacing) at the Trevor Nichols Research Center in Fennville, MI (Tart Cherry 4). The trial was organized as an RCB with four replications. Applications began 20 June at initial infestation with ripe fruit and were reapplied on 7-day intervals until 19 July (Table 1). Test materials were applied with a FMC 1029 airblast sprayer calibrated to deliver 100 GPA at 2.5 mph.

Two-pound samples of random ripe fruit were hand-picked from each plot on 10 July, 17 July, and 24 July. The fruit were evaluated using the Washington State Department of Agriculture brown sugar method by crushing them in a sugar solution (7 pounds brown sugar to 5 gallons water). The larvae were allowed to float and were subsequently counted. Counts of the total larvae per pound of fruit were analyzed using ANOVA with means separation by Tukey’s HSD (P = 0.05) after square root transformation of the data.

In the 10 July evaluation, after most plots had received the first three insecticide applications, nine treatments reduced SWD compared to the untreated check. These included Apta followed by Verdepryn, Movento followed by Baythroid, Imidan, IKI-3131, Delegate with Preference, Delegate with Accudrop, one application of Verdepryn on 4 July, JetAg, and JetAg followed by Delegate (Table 1). However, it should be noted that none of the treatments were statistically improved compared to Verdepryn (application timings DE) that had still not received its first treatment, and therefore served as a second untreated check through the 10 July evaluation date.

In the 17 July evaluation, seven treatments reduced SWD to 10.8–33 SWD per pound of fruit compared to the untreated check (166 per pound). These plots received three applications of Verdepryn (starting at 28 June), or four applications of Delegate with Preference, Delegate with AG16134, Delegate with Accudrop, Verdepryn (beginning on 20 June), JetAg followed by Delegate, or Delegate (Table 1).

In the 24 July evaluation, two treatments reduced SWD to <10 per pound of fruit compared to 73.3 in the untreated check. These treatments include five applications of Delegate with AG16134 and four applications of Verdepryn (starting 28 June) (Table 1). Across all evaluation dates there were no significant differences among plots receiving two to five applications of Verdepryn.¹

Footnotes