Control of Apple Clearwing Moth, Synanthedon myopaeformis, with Tree-trunk Applications of Reduced-risk Insecticides, Nematodes and Barriers.

Judd, G.J.R., Bedford, K.E., and Cossentine, J.E. (2015). "Control of Apple Clearwing Moth, Synanthedon myopaeformis, with Tree-trunk Applications of Reduced-risk Insecticides, Nematodes and Barriers.", Journal of Entomological Science of British Columbia, 112, pp. 69-83.

Abstract

Apple clearwing moth (ACM), Synanthedon myopaeformis Borkhausen (Lepidoptera: Sesiidae), was discovered in an apple orchard in Cawston, British Columbia in 2005. This xylophagous, invasive European species has become a serious problem in high-density apple orchards where size-controlling rootstocks are attacked by the wood-boring larvae. Seven screening trials with reduced-risk insecticides for conventional (seven treatments) and organic apple production (three treatments) were established in two commercial high-density mixed-variety apple plantings in Cawston. Our objectives were (1) to screen several new synthetic insecticides having novel chemistries that purportedly have reduced risks, (2) to evaluate use of several organically-approved spray materials, including nematodes, and (3) to compare the efficacy of various products when applied at different times during the growing season. Single, hand-gun sprays delivering treatments in 2000 L of water ha−1at 200 psi were applied as curative sprays targeting mature larvae inrootstock-scion graft unions in May and October 2008, and June 2009. Among seven treatments tested, only the insect growth regulator, Rimon® 10 EC (10% novaluron), at 2.4 L a.i.ha-1, caused significant reductions in adult emergence compared with untreated controls in all experiments. When applied twice as preventative treatments during flight of male ACM in 2008, Altacor®, Belt®, Delegate™ and Rimon all caused significant reductions in adult emergence the following year; Rimon caused the greatest reduction (-96.4%). In a similar 2009 trial only Rimon reduced populations the following year. One curative or two preventative applications of the organic materials, Entrust®, Crocker’s Fish Oil®, or Purespray Green Oil™, at any spray timing, did not control ACM. The nematode, Steinernema feltiae (Filipjev) (1×105infective juvenile nematodes / 100 ml of water / tree) provided significant control of ACM in one spring 2008 trial. In two 2009nematode-only experiments, a sawdust paste tree-trunk barrier applied over nematode applications made either in May or August, caused significant reductions in emergence of ACM adults. Curative tree-trunk sprays of Rimon 10 EC at the tested rate are recommended for control of ACM inconventional apple orchards. There is no effective organic control for ACM at this time, but tree-trunk barriers and nematodes may warrant further study.

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