What’s bugging you? May 2, 2012

Spring is in the air with fruit trees and lilacs blooming. If you have apple trees, now is the time to plan your management strategy for the dreaded codling moth.

Without some kind of spray program, expect to have a lot of "wormy" apples.

But first I have to ask you — why grow apples? We have plenty of good commercial apple orchards in our area and an abundance of good tasting fruit. And someone else is taking care of spraying for codling moths for you.

But if you are still hell bent to grow your own apples, there are a few chores that must be done. The codling moth in our area is a key pest of apples and in some districts it is mandatory to either spray to control this pest or spray a chemical at bloom time that removes most of the fruit. This is to protect our apple industry.

Codling moth adults will be emerging now but their egg-laying activity won't peak until later in May. There are three generations a year with the most damage occurring during the second generation. This second generation usually peaks sometime in July. All of this timing is dependent upon day and nighttime temperatures.

First sprays should start two weeks after petal fall with a second application in two weeks. This will take care of most of this first wave of activity. About six weeks later, the heaviest attack will occur from the second generation. Again, two applications, two weeks apart will handle most of the activity.

Depending upon how late maturing your apple variety is, a fifth and maybe a sixth application will be necessary to target a smaller third generation. This would be in late August or early September.

The success of this spray schedule is dependent upon using one of the synthetic pyrethroid insecticides with common names such as permethrin or fenvalerate. The insecticide container will list this under the active ingredients. Ask a sales person for help if you are unsure. Only pyrethroids will give you this extended control.

The spray schedule I have outlined is the bare minimum you can get away with. You will still have some "wormy" apples but most of your fruit will be clean.

Moths like to lay their eggs where leaves touch apples or where apples touch apples in clusters. Fruit thinning will not only help produce larger apples but will help reduce codling moth "stings."

Crabapples are not immune to attack from codling moths. In those districts that mandate homeowners control codling moths, crabapples with fruit larger than a dime at maturity will have to be sprayed too. Or you can chemically remove fruit instead. Smaller mature fruit will not support the development of coding moth larvae.

Last but not least, a very important management tool that does not rely on insecticides is a fall cleanup of fallen apples and tree leaves. Most of these apples will be infested.

I do have one last request before signing off. If you grow your own apples, take care of your codling moths. Commercial apple growers need all the help they can get. And I want this industry to continue to be successful so that I can enjoy fresh apples each year. I'm too busy or maybe lazy to grow and manage my own.

Jim Leser retired to Cedaredge after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a master gardener.

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