Codling moth degree day accumulations are at 1540 in Henderson and 1970 in Cleveland County, which coincides with about 55% and 90% emergence of the second generation adults. Second generation populations appear to be low throughout the region, which is not surprising considering the excellent control of the first generation in virtually all orchards recently visited. By this time everyone should have applied a preventive application against the second generation, and additional sprays should be based on pheromone trap captures of 5 or more moths per trap per week. In mating disruption orchards use a threshold of 3 cumulative moth captured over a two week period.
Woolly apple aphid (WAA): Woolly apple aphids are showing up with regularity in many orchards and appear to be related to applications of Zivalgo for first generation codling moth. We have not yet conducted an extensive survey in commercial orchards, but the relationship seems to be clear in our research plots at the MHCRS.
The same situation occurred when Delegate was first registered in 2008, with high WAA following Delegate applications against the first generation codling moth. This was due in part to toxicity of the insecticide to a key parasitic wasp of WAA – Aphelinus mali. Over several years the flare up of WAA declined as the parasite apparently developed some tolerance to Delegate. Parasitized aphids are black (referred to as mummies), and those from which a parasitic wasp emerges have an exit hole on the aphid’s exoskeleton.
There is no threshold for WAA, primarily because insecticides only provide mediocre control, and eventually parasites will reappear and suppress the population. At this time damage is most likely to be limited to accumulation of honeydew on fruit where there are large colonies. The most effective insecticide is the organophosphate Diazinon, but only the 50WP is registered on apple and it is difficult to source. Also, some buyers of fruit do not allow organophosphate use. Other insecticides that can provide some suppression at high rates include Assail, Sivanto Prime, Closer, and Beleaf, but none will provide good knockdown activity. Movento has a higher rating than these materials, but it is most effective when applied preventively due to its systemic activity.
