CHEMICAL CONTROL OF TWOSPOTTED SPIDER MITE ON GREENHOUSE MARIGOLD, 2012

The efficacy of five miticides, used alone and in combinations, for twospotted spider mite control on greenhouse ornamentals was evaluated compared to a non-treated check at the Gulf Coast Research and Education Center, Wimauma, Fla. in Apr-May 2012. Two seeds of ‘Petite’, mixed colors marigold, per 2-inch cell, were planted into polystyrene trays on 17 Feb. The resulting seedlings were transplanted, one each, to 6-inch pots on 21 Mar. Each plant was pinched to four nodes (26 Mar) and infested with about 25 motile TSM from a laboratory colony (28 Mar). Plots consisted of three pots. Treatments were replicated six times in a RCB design. The plants were spaced so that those from different plots would not touch. Pre-treatment samples were taken on 2 Apr and treatments were applied 1 day later using a hand-held sprayer with a spray wand outfitted with a nozzle containing a 45° core and a no. 4 disc. The sprayer was pressurized by CO2 to 40 psi and calibrated to wet the leaf surfaces thoroughly without excessive run off. Sampling continued periodically from 1 through 42 DAT. Samples consisted of three leaves per plot (one from each plant) and were transported to the laboratory where the numbers of motile and egg forms of TSM on the lower leaf surfaces were recorded with the aid of a dissecting microscope. Distinctions could not be made between viable and non-viable eggs, thus total eggs were recorded. Data were transformed log10(x+1) prior to ANOVA and means were separated by Fisher’s Protected LSD test (P≤0.05). Non-transformed means were reported.