Greenhouse Whitefly Control on Marigolds in Michigan, 1993

Marigold plants were raised from seed in 6 inch clay pots for 10 weeks reaching 10-12 inches in height in a research greenhouse infested with greenhouse whitefly at Michigan State University. Each treatment and a control were replicated 6 times with each replication being an individual plant. Precounts were taken on 22 Jun by counting all whitefly larvae and pupae under a dissecting microscope on the undersides of 5 randomly selected leaves from each plant. The treatments were then blocked based on these precounts. Insecticide applications were applied on 24 Jun and repeated on 1 Jul with a R&D CO2 sprayer with a single 8008 nozzle at 50 psi until first runoff. The Marshal/Suscon treatments were applied to the soil surface of the pots. Postcounts were made in the same manner as precounts on 13, 21, 28 Jul, 4 and 12 Aug. The number of whiteflies reported for all sample dates is the total number of whitefly including larvae and pupae.