Effect of Pyrethroid Insecticides on Citrus Rust Mite Control, Fall, 2013 *

While foliar sprays of pyrethroid insecticides have been observed to cause resurgence of mite pests, some such as fenpropathrin, are labeled for mite control including citrus rust mite (CRM). The objective of this trial was to evaluate response of CRM populations on citrus to frequent application of two pyrethroid insecticide and one pyrethroid + abamectin premix, both used in Florida citrus, particularly for control of the Asian citrus pysllid, Diaphorina citri . The experimental block at Southwest Florida Research and Education Center Immokalee, Florida consisted of 6-yr-old sweet orange “Hamlin” orange trees planted at a density of 132 trees/acre. Three pyrethroids applied weekly and biweekly were evaluated for their effect on CRM. Six treatments and an untreated check were randomly distributed in an RCBD with 4 replicates in five-tree plots over four rows separated by buffer rows. The first application was made on 5 September and repeated weekly or biweekly. Trees were sprayed from both bed and swale sides using a Durand Wayland AF100-32 air blast speed sprayer operating at 1.9 mph and 350 psi equipped with three John Bean ceramic nozzles 5, 4, 3 on each side delivering 90 gpa. Three central trees were sampled per plot. Four fruits, one from each side of the tree, were examined using 2–4 lens fields per fruit to count CRM. Data were subjected to ANOVA and means separated using LSD ( P  = 0.05) are presented.

The pretreatment count averaged 3.4 ± 0.4 CRM per lens field. All treatments resulted in significant reduction in CRM through 2 Dec, except both weekly and biweekly treatments of Mustang Max + 435 Oil on 18- September and the biweekly treatment on 3 October ( Table 1 ). A greater reduction of CRM was observed with weekly than biweekly treatments of Mustang Max + 435 Oil but this difference was not seen for Gladiator + 435 Oil or Danitol + 435 Oil except for the latter on 25 September. No phytotoxicity was observed.

Author notes