Tabm Greenhouse Ground Cover Test, 1990

Larvae feeding on dandelion plants (Taraxacum officinale Weber) were treated using a herbicide sprayer and held in a greenhouse to test insecticides for use in the ground cover under apple trees in the spring. Six dandelions were grown from seed in each of 24 nurSery flats (31 × 56 cm) (Kaden Co., Dayton, Ohio). Twenty field strain, third through early fifth instar TABM larvae were placed on the plants in each flat on 11 Oct. Tape with Insect Trap Coating (The Tanglefoot Co., Grand Rapids, Mich.) on the rims of the flats prevented larval escape. After larvae had opportunity to construct shelters, treatments were made using a Bean herbicide sprayer calibrated to deliver 935 liters*ha-1 on 12 Oct (Asana XL applied at 987 liters*ha-1). The mean daily max/min temperatures in the greenhouse were 24.5 and 13.2°C, respectively. Photoperiod was maintained at 16L:8D to prevent diapause. On 9 Nov larvae, pupae and pupal exuvia were removed from flats and live larvae and pupae transferred to the laboratory (28°C, 16L:8D) where they where held on diet until adult eclosion was complete in the control. Percent mortality was based on the initial no./ flat less those removed from the trap coating. The data was analyzed as a completely randomized design.