Hello Apple Growers,
I knew it was only a matter of time before we found resistant populations of
obliquebanded leafroller. New York growers have been plagued for years, and populations
resistant obliquebanded leafrollers have been in Western Massachusetts for the
past couple of years. Now we have them in Rhode Island.
We’ve always had obliquebanded leafrollers, but now I believe we have a
population obliques that are resistant to the commonly used insecticides. The
good news is there are insecticides that do control obliques, the bad news is
the new insecticides are very expensive, and now it is late in the growing season
to control this beast.
Obliques are difficult to find. The pale green caterpillars with black heads
are usually hidden under a leaf or curled up in a leaf. To scout for this insect
look for a leaf that is covering an apple. Pull up the leaf and see if you find
a larva. See pictures below.
If you do find the damage and/or larvae, I recommend you spray as soon as you
can with one of the following insecticides: Altacor, Delegate, ProClaim, Rimon,
Intrepid, Voliam Flexi, Belt, or Dipel. Most of these insecticides have a 14
day preharvest interval, except Delegate (7 days) and Dipel (0 days).
The larvae in the orchard now will pupate, emerge as adult moths, and lay eggs
for another generation. The next generation feeds primarily on leaves, but can
also do some fruit feeding. If you do spray now and still need to spray for the
next generation, it is recommended you use a different insecticide for the next
generation. These insects develop resistance quickly, so you want to use a different
insecticide for different generations.
If you have questions, please call me at 874-2967.
I will be collecting leaves and soil samples this week for leaf tissue analysis.
If you want me to take a sample and haven’t told me yet, this is your last
chance. This service is for commercial growers only. The cost for a leaf and
soil sample is $35 for apple and peach samples, $40 for other plant samples.