What to choose
Orchardists now have about ten products to choose from for controlling the key pests codling moth and leafrollers, not counting the traditional organophosphate materials. Some products target leafrollers, some codling moth, and some target both pests.
Dr. Jay Brunner, director of Washington State University's Tree Fruit Research and Extension Center in Wenatchee, said the regulatory environment has changed, and over the past decade, chemical companies have been developing new products to replace the old ones.
Two new pesticides are expected to be available for the 2008 season—Altacor (rynaxypyr) and Delegate (spinetoram).
"This is good news; you have lots of options," Brunner said. "These products can work very well."
However, the bad news is that understanding all the choices can be challenging.
Researchers are concerned that if growers just switch the old products for the new, the pests will soon develop resistance. Instead, growers need to think about the entire season's pest management program and be good stewards of the new products.
Some of the new products have the same mode of action. For example, Delegate (spinetoram) has the same mode of action as Success (spinosad); Assail (acetamiprid) and Calypso (thiacloprid) are both neonicotinyls; and Altacor (rynaxypyr) is in a new class of insecticides that affect the muscle function (rather than nerve function) of the insect and is highly selective. Another product called Belt (flubendiamide) is in the same class as Altacor, but Brunner said more research is needed on it. It was used under an Experimental Use Permit last season and is expected to have a full registration this year, though possibly not in time to treat the first generation of codling moth.
Altacor has provided good control of both codling moth and leafrollers in field trials, Brunner reported. Delegate is a good leafroller product and is also effective against thrips. While it suppresses codling moth, it has less residual activity than Altacor. However, both are good products to fit into a pest management program.
Brunner warned growers not to use the same class of insecticide to target two consecutive generations of a pest. Pesticide labels now indicate the class of insecticide.
Mating disruption is the foundation of an integrated pest management program in apple because it reduces populations of codling moth over time, and all chemical control programs work better with mating disruption, Brunner said. Mating disruption can reduce the need for supplemental insecticides, which is one of the best resistance management strategies.