Control of Silverleaf Whitefly on Poinsettia Under Greenhouse Conditions, Summer 1997

Poinsettias, ob tained as rooted cuttings, were potted in 15-cm pots and allowed 8-wk growth (15-20 cm tall) before use. The plants were fertilized once with Osmocote (14-14-14) and irrigated every d for three minby overhead misters. On day (0), ten whiteflies were caged on the 5th (counting from top leaf of about 1 cm2 down), and a 2.5-cm-diam circle was drawn on the leaf around the cage perimeter. Twenty-four h later the adult whiteflies were removed. After egg eclosion (10 Jul), a pre-treatment count of the no. of nymphs was taken, and it was followed by treatment application. Post-treatment counts of live nymphs were taken weekly for two wks. Treatments were applied using a backpack sprayer at approximately 25 psi. A RCB design was used with five replicates per treatment. Data were transformed log10 + 1 prior to analysis to satisfy the assumptions of the analysis of variance, and LSD (P = 0.05) was used to separate the means.