Evaluation of Foliar Insecticides for the Control of Tipworm in Cranberry, 2015 *

In the summer 2015, an experiment was conducted to assess the efficacy of insecticides currently labeled for use in cranberry (Altacor, Diazinon, Assail, and Orthene), a registered insect growth regulator (Rimon), softer chemistry insecticides labeled on cranberry (Grandevo and Venerate), and insecticides not currently labeled on cranberry (cyclaniliprole, Closer, Fanfare, Movento, and Exirel) on cranberry tipworm. This experiment was conducted in a mature cranberry planting on a commercial farm near Warrens, Wisconsin. The trial consisted of 13 main effect treatments arranged in an RCB design with four experimental replicates. Each replicate plot was 10 × 20 ft. Foliar applications of these insecticides were done at 13:00 hours on 27 Jul 2015 (application A; early fruit set) and again on 3 Aug 2015 (application B; medium fruit set). Insecticides were delivered at 28.4 GPA and 31 psi with a CO ₂ backpack sprayer equipped with four 8,003 flat-fan nozzles on a 6.7-ft boom. The control plots (untreated check) received no insecticide. Plots were examined for the presence of tipworm larvae 7 days after the second application (7DA-APB) on 10 Aug 2015, 14 days after the second application (14DA-APB) on 17 Aug 2015, and 21 days after the second application (21DA-APB) on 24 Aug 2015. Using sweep nets, the number of tipworm larvae, consisting primarily of late instar larvae, collected in 20 random sweeps was counted in each plot. Data were analyzed using ANOVA and means separation by Fisher’s LSD test at P  = 0.5.

Most treatments did not reduce the number of tipworm larvae consistently throughout the experiment ( Table 1 ). Only Fanfare and Movento reduced the number of tipworm larvae consistently, with control ranging from 74% with Movento at 7DA-APB to 98% with Fanfare at 14DA-APB. Cyclaniliprole, Diazinon, and Rimon significantly reduced the number of larvae at certain times post application ( Table 1 ). For example, Rimon provided control at 14 and 21DA-APB with control ranging between 73 and 79%. Diazinon provided up to 73% control while Cyclaniliprole only reached 48% at 7DA-APB. Other treatments (Altacor, Assail, Closer, Exirel, Grandevo, Orthene, and Venerate) did not significantly reduce the number of tipworm larvae at any time post application ( Table 1 ).

Author notes