Effectiveness of a Dormant Application of Sunspray 6E Oil for the Control of the Honeylocust Spider Mite on Established Thornless Common Honeylocust, 1994

Honeylocusts, with an avg DBH of 7 inches and located on the property of Longwood Gardens, Kennett Square, PA, were used to evaluate the effectiveness of a dormant treatment of Sunspray 6E oil for the control of honeylocust spider mites. On 8 Apr, the infested honeylocusts were treated with a 2.5% solution of oil using an SDI sprayer operating at 400 psi with a no. 18 disc nozzle tip in an FMC gun. Treatment was applied between 6-8 AM under clear skies, 38°F, 30% RH, <5 mph winds. An avg of 23 gal. of finished spray was applied to each tree. On 7 Apr, pre-treatment counts of live mites were made by examining a 10-inch-long branch section, as measured from the terminal end, from 11 different trees. On 15 Apr (7 DAT), the effectiveness of the treatment was evaluated by sampling 3 treated and 3 untreated trees. Four branches 10-inches in length, as measured from the terminal end, were collected from each tree and examined microscopically for live mites.