Control of Hemlock Woolly Adelgid with Joust 4L (Oxythioquinox), 1992

An experiment was conducted at Longwood Gardens, located in Kennett Square, Pennsylvania to determine the effectiveness of a foliar spray of the high labeled rate of Joust 4L for controlling hemlock woolly adegids on eastern hemlocks. Trees had moderate infestations of aestivating flrst-instar adelgid nymphs. On 1 Sep, four trees ranging in height from 3 to 4 m were treated using a Hypro Corp. diaphragm sprayer operating at 400 psi with a Green Garde JD-101L nozzle. Approximately 13 liters of spray mix were applied to each tree. Treatment was performed between 8 to 9 am, under clear skies, 17°C, 45% RH, and < 2 mph winds. The effectiveness of the treatment was evaluated on 21 Sep by sampling four branches from 4 sprayed and 4 unsprayed trees. The first 100 adelgids on each branch encountered were recorded as dead or alive; 1600 adelgids were examined for the treatment.