Island Apple IPM
May 8, 2006 Recorded Apple Pest Message in Print.
Apple Scab: We had a major apple scab infection period last Tuesday and Wednesday (May 2-3), as was predicted. We are quickly approaching the end of primary apple scab season. Orchard Radar predicts that 78% of overwintering scab spores have matured and more than half of these spores have already been discharged by previous rainy periods.
I have not seen any apple scab lesions yet this year, but this is not unexpected. Our first severe apple scab infection period was April 24-25. Lesions from this infection period are probably not visible before May 7 in Greenville or May 9 in Newport County. And lesions do not all become visible at once. It takes awhile for all the lesions to form. I do expect to see lesions this week. The lesions from last week’s infection period on May 2-3 are expected to start appearing on May 15th.
Continue to keep your trees well protected over the next couple of weeks. With all the showers predicted for the foreseeable future, there is a good chance you will need to spray between showers. Do not go more than 7 days between fungicide applications this time of year.
European red mite: I have seen more European red mite nymphs in some orchards. Scout your trees now to determine if your trees have too many red mites. Look on the underside of the oldest fruit cluster leaves with a handlens. The small red mite nymphs are fairly easy to see. Especially check tufts of leaves that are growing directly on a large limb. Red Delicious trees tend to have many such tufts – and Red Delicious is certainly a good variety to check for mites.
The threshold for red mites at petal fall is 1 mite/fruit cluster leaf. I admit that I would recommend spraying at petal fall if I found even 1 mite per whole cluster. There are many miticides to choose from. A good rule of thumb is not to use the same miticide two years in a row so the mites don’t develop resistance. So, if you used a miticide last year, use a different one this year. This is especially true for Apollo and Savey. Also, these two miticides are so similar that you can not alternate between these two.
Be prepared to spray an insecticide at Petal Fall. We recommend full rates of Imidan or Avaunt to control plum curculio and European apple sawfly. Petal Fall is also the time to start thinning sprays of Sevin and applying Apogee, if you plan to use Apogee to control tree growth.
I plan to show pictures of leafminer eggs at the twilight meeting on May 11th. There will also be lots of information about fruit thinning. Win Cowgill from Rutgers will be there along with Jon Clements and Wes Autio from UMASS. Please come to the RIFGA twilight meeting in Massachusetts. See the Apple IPM website for details at http://www.uri.edu/research/ipm and see Meetings.
Next message will be recorded Monday, May 15, and printed May 16. 949-1456.