Rhode Island Apple IPM
July 17, 2010: Recorded Apple Pest Message in Print

Hi Apple Growers, July 17
This week was cooler than last week and most orchards received some badly needed rain.

I didn’t check any apple maggot fly traps this week, but looking at data from New York, they have reached the spray threshold for apple maggot flies in 4 out of 16 orchards and they caught some apple maggot flies in 15 out of 16 orchards. The rain over the last week has most likely allowed more apple maggots to emerge from the soil. If it’s been more than 2 weeks since your last insecticide application there is a good chance you’ll want to spray again soon. Use half rates of Imidan or full rates of Avaunt, Calypso or Assail.

I’ve seen some rose leafhoppers in a few orchards, but not in very high numbers. Leafhoppers are primarily a nuisance and don’t cause very much damage. In most situations I think you can probably wait until closer to harvest and control them with Sevin if necessary. If you do use Assail or Avaunt for apple maggot control, this should also control leafhoppers.

Leafhoppers you find now are rose leafhoppers. Rose leafhoppers overwinter on roses and migrate to apples during early summer. Another leafhopper, white apple leafhopper, spends its whole life on apples. White apple leafhoppers are between generations right now. According to Orchard Radar, white apple leafhopper second generation eggs should begin hatching around July 22 in Greenville and July 25 in Newport County. I didn’t see any high populations from the first generation white apple leafhopper and I don’t expect to see many problems from the second generation.

I’ve seen more orchards with high numbers of predatory mites. I think these orchards also have high numbers of rust mites serving as food for the predatory mites and not harming apple leaves. The rust mites are microscopic and I didn’t look at leaves under a microscope so I can’t be sure. I do know I’m finding lots of predatory mites and not many pest mites. I’m thrilled!

I’ve looked for obliquebanded leafrollers in orchards where we found late season feeding last year. I’m happy to report that I have not found any leafrollers. I’m thinking that maybe we still have population of obliquebanded leafrollers that are controlled by Imidan. Perhaps last year, with all the rain, Imidan was washed off quickly and allowed obliquebanded leafrollers to survive. That would be good news! I’ll keep looking for them!

When showers are very scattered, Orchard Radar may not be very helpful predicting how soon you need to reapply pesticides. According to Orchard Radar for Greenville, over two inches of rain fell over the past week. This may or may not be the case in your orchard. It is best to measure rainfall at your property to know whether or not your trees have received over two inches of rain, indicating the need to reapply pesticides.

I will try to record a message next week, but I’m not sure I’ll be able to. I’ll be away for some small fruit meetings for most of next week.

I hope to make it to several orchards next week!

Heather