Control of Western Flower Thrips on Dwarf Roses, 1995

One hundred and twenty mini-rose cuttings of each cultivar were planted in 6 inch pots and grown in a western flower thrips-infested greenhouse compartment at the Ohio Agricultural Research and Development Center, Wooster, Ohio. Plants were fertigated using 150 ppm 15-16-17 on a 3 fertilizeni leach schedule. On 13 February 1995, when the plants were 13 wk old, treatments of two systemic insecticides were applied at a range of rates. Applications were weighed out on a Sartorius balance and poured onto the soil surface from plastic spoons. The plants were watered following the application. Ten treatments were applied to three pairs of plants (a pair comprising both cultivars) in each of four replicates of a completely randomized design. Each replicate occupied a separate bench in the compartment. Post-treatment counts were made 21, 35, and 49 DAT. WFT were sampled by alcohol-washing flowers picked from each of the plants in a treatment group. Number of immature thrips were recorded on a per plant basis. Larval WFT density was expressed as number of thrips per flower to compensate for the variable number of flowers per plant. Temperature and humidity were 25±5 °C and 60±25 %RH during the trial.