Cotoneaster, Control of Two-Spotted Spider Mite, Lake CO., Ohio, 1990

Cotoneaster growing in 3 gal (11.7 liter) containers at a nursery in Lake Co., OH, were used to evaluate efficacy of selected pesticides against two-spotted spider mites. A CO2 compression sprayer at 30 psi with a single Teejet SS8004 flat-fan nozzle was used to apply treatments to run-off Infested plants were selected at random and placed in groups of 4 replicates per treatment. The first application was applied to all plants 3 Jul under sunny skies, 27°C, and 16-24 km/h winds; the second application to selected plants was on 13 Jul under cloudy skies, 19°C, and 16-24 km/h winds. Plants received over-head irrigation every other day or as needed. Treatments were evaluated 6 and 24 days after the second application by removing four, 10-13 cm long branch tips from each of the 4 replicates per treatment. Samples were placed in plastic bags and transported, in coolers, to the laboratory. All samples were processed by passing them through a mite brusher 6 times to dislodge mites to a rotating glass plate coated with Tween-20. Dislodged mites were counted with the aid of a binocular dissecting microscope.