Watch for codling moths

It’s spring and the fruit trees are about to bloom. It’s time to start planning how to reduce the chance that you will have to share your apples with codling moths and apple maggots. I’ll cover the codling moth this week and apple maggot in next week’s column

Adult moths are about half to three quarters of an inch long with mottled-gray wings tipped with coppery brown. They start appearing two to three weeks after the tree reaches full bloom. Each moth lays about 50 to 60 eggs on leaves, branches and fruit. After the eggs hatch, the larvae feed on the tree for a short period before burrowing to the core of young fruit. The larvae are pinkish white with brown heads and leave a frass-filled hole on the outside of the fruit. The larvae feed for three weeks and then leave the fruit to pupate for two weeks. We can get several generations a year making control necessary throughout the fruit season. The larvae over-winter in cocoons under loose bark or in debris on the ground.

Good control starts with cleanliness. Rake up all old fruit and leaves in the fall to remove hiding places and over-wintering cocoons. Gently remove bark scales from trees to further reduce over-wintering places.

Because the moths and larvae are only exposed to the open air for very short periods of time, any controls have to be timed to be on the tree before they enter the fruit or pupate.

Pheromone traps hung in the trees are the most accurate way to tell if adult moths are present. The traps are sticky pieces of cardboard baited with the scent of the female moth. The male moths, thinking they have found their true love, get stuck on the trap. Once they start showing up, it’s time to get the rest of the control program under way. Traps are readily available at garden centers and should be hung fairly high in the tree near fruit areas.

Check the traps every couple of days for the presence of moths. Once they are present, begin a regular spray program every 10 days. If no moths show up in the traps, you probably can skip spraying until they do.

Malathion is the conventional spray for codling moth. A relatively new one is Spinosad, a new type of pesticide that is OMRI listed for use on organic production. It has to be ingested by the insect to be effective which makes it less likely to harm nontarget predatory insects.

A last method is the use of highly processed kaolin clay called Surround WP. This food-grade clay is mixed with water and sprayed on the tree and fruit leaving a white, nontoxic coating. The tiny particles don’t kill the larvae but camouflage the fruit so it looks less like a meal and irritates the insects’ skin so they don’t hang around. This treatment may be hard to find locally. Always use and store pesticides according to the label directions.