Apple maggot flies. I don’t have many apple maggot fly traps set up, but I did get to check a few traps this week. At URI’s East Farm orchard I caught a total of 8 apple maggot flies on 3 traps over the past week. That is over the threshold of 2 flies per trap and we will apply a half rate of Imidan this week. At another orchard, we did not catch any apple maggot flies. Early August is generally peak time for apple maggot fly trap capture and activity. If you have not applied an insecticide for 2 weeks, consider applying Imidan or Avaunt. A half rate of Imidan is sufficient to control apple maggot flies; I am not sure if a low dose of Avaunt will also be sufficient.
Other insect pests that may be in your orchard now include rose leafhopper, potato leafhopper, apple blotch leafminer, and mites. Rose leafhoppers may be present as flying adults or crawling nymphs now. Leafhoppers are fairly easy to control with Thionex, Provado or Sevin. Potato leafhoppers are found primarily on the ends of branches and cause these outer leaves to cup and become pale or yellow. Potato leafhoppers may also transmit fire blight, so during a year like this one, where we have fire blight in several orchards, it is a good idea to control potato leafhoppers. Potato leafhoppers should be controlled with Imidan, but if the Imidan doesn’t work, use Thionex, Provado or Sevin.
Apple blotch leafminer second generation mines are all visible from the upper leaf surface now. There may be some orchards where there are more than 2 mines per leaf for this second generation. It is really too late in the season to effectively control leafminer. You can’t control them once the mines are visible from the upper leaf surface and the next generation is too spread out to effectively be controlled.
European red mites have successfully been controlled in some orchards using the miticides Acramite or Zeal. Red mites have also been controlled at URI’s orchard by mite predators. I’ve also seen a high population of mite predators at a commercial orchard, successfully controlling red mires. The threshold for red mites for August is 7 mites per leaf.
All this humid weather is perfect for developing fly speck and sooty blotch. Keep you fruit protected with Sovran, Flint, captan, or captan plus Topsin M.
ReTain is a useful tool for extending your harvest season. It can delay ripening by 7-10 days – if it is applied 3-4 weeks before expected harvest date. You wouldn’t want to apply ReTain to all your trees, but it could be a good idea to delay ripening in some blocks.
Please let me know if you want to participate in the RI Fruit Growers’ Providence Journal ad on September 12. The cost is $80 per farm. Also, please tell me if you’d like a leaf tissue sample taken in your orchard. This is for commercial growers and the cost is approximately $27 per sample.
Thanks for calling. Next message will be recorded Tuesday, August 7th.