Forecasted weather over the next 24 hours are predicting heavy rain events with accumulations nearing 1″. Residue of insecticides for codling moth will likely requite re-application during next available management window to maintain codling moth control.
John Wise, Entomologist, Michigan State University Extension has studied and characterized insecticide residual based on active ingredient class and mode of action. His article on this topic is a must read for all growers.
These materials require 24 hours of drying prior to a rain event to fully move into the developing fruit and leaf cuticle. Neo-nicotinoids, being ‘translaminar’ or locally systemic, generally, have strong weathering capacity within the cuticle up to 0.5″ of rainfall. However, surface residue of these materials is poor after a very brief period and 1″ of rainfall compared to pyrethroids and carbamates. Insects that feed on fruit or foliage will continue to ingest the neo-nic insecticide within the plant tissue after after 1″ of rain.
In untreated Red Delicious we are now seeing 7% codling moth (CM) fruit injury on the morning of June 10th 2019. The CM feeding and entry sites are very small and exhibiting a ‘red ring’ around the entryway. Within the next two weeks the larva entering the fruit will begin feeding on the seeds, forcing frass out from the calex end of the fruit, making the infestation very visible.
In the timeline chart of adult pheromone trap captures we see that we have passed the first CM adult peak emergence. This trend will continue through complete larval emergence, increasing in adult numbers over the next two weeks as more adults emerge, mate and lay eggs. We are likely to see a second or ‘B’ peak, representing another large late emergence of adults in mid-late June.
The codling moth Biofix occurred on 17th May, first emergence of larva at 220DD on the 2nd of June. We have to date accumulated 308 DD50 and within the past 8 days significant CM injury is now visible in orchards that were not managed for this pest.
However, even if injury is occurring, effective applications can still be made after this coming rain event with a viable application window on Wednesday June 12th.
To best assess efficacy of your management program, scouting for levels of infested fruit injury should be considered this week. If economic CM damage has occurred, your assessment of the injury in the field now will help to determine the efficacy of the materials you are using, define the problem so as to modify pest management decisions for the next generation beginning in late July / early August and 1st generation in 2020.
Other management options to consider:
San Jose Scale crawler emergence likely this week. The first adult trap catch was on the 20th May with 1st gen. crawler development in process and crawler emergence predicted to occur at approximately 260-360 DD50, period predicted to begin on 6/7 or 6/8. We have not trapped crawlers as of the 10th of June at HVRL.
Plum Curculio (PC) control sprays are no longer necessary during the rest of the season.
Black Stem Borer (BSB): Although we have been trapping for and catching black stem borer, we have not seen boring injury to bolts of apple branches soaked in ETOH over the past three weeks. Orchards should be scouted for BSB tooth pick frass and small 1.5mm holes in the trunks of young apple plantings. Especially apple in heavy wet soil or well drained dry soil.
Obliquebanded Leafroller (OBLR) DD accumulations are now at 157 of 350DD needed for emergence. Biofix occurred on 3rd June. Peak moth flight, first egg hatch is predicted for the 19th of June. Apply protective sprays with the first spray timed to coincide with the first hatch of larvae at approximately 350 DD base 43F after biofix.