Rate Response of Tolfenpyrad for Control of Citrus Rust Mite, 2014 *

Fruit damage caused by the citrus rust mite (CRM) is a concern to fresh fruit growers in Florida and elsewhere. Juice yield and quality can also be affected. The present trial comparing rates of Apta and a standard was conducted at a commercial site in Labelle, Florida on 5-year-old ‘Valencia’ orange trees planted at 15 × 22 ft. spacing. An RCB design was used to assign four replications of each of the five treatments and an untreated check to 8-tree plots within rows separated by an untreated buffer row. Applications to both sides of the tree were made 22 Oct using a Durand Wayland AF100-32 air blast speed sprayer operating at 1.9 mph and 300 psi. Two fruit on each of the center six trees per plot were sampled weekly from 24 Oct to 23 Dec using a 14× Bausch & Lomb Hastings hand lens. A “lens field” of ∼1.0 cm ² was viewed on two partially shaded areas of each sampled fruit. The mean number of mites per two lens fields per fruit is reported. All data were subjected to ANOVA for treatment effects with means separated by LSD contingent of a significant F ( P  = 0.05) value. A pre-treatment sample on 16 Oct indicated an average of 2.65 ± 0.45 (mean ± SE) mites per lens field.

Mite numbers remained high on check trees through 41 days after treatment (DAT) and then began to decrease. All treatments through 48 DAT provided significant reduction of mites compared with the untreated check with no differences between remaining treatments. However, the two lower rates were no longer different from the check at 55 DAT and no treatment effect was seen at 62 DAT. No phytotoxicity was observed ( Table 1 ).

Author notes