The apple harvest is almost over. We have picked so many red delicious apples at our house, we don’t care there are still some on the tree. I had thought a freeze in late May had destroyed all the flowers. Surprise!
The recent winds have blown down many of the apples remaining on the tree. I gather up the good ones, and until last week, I have left the wormy, damaged, bruised or partially eaten apples under the tree in a pile, waiting to go in the trash. I have been lazy about throwing out the bad apples, which is a bad idea because it encourages pest problems.
The reason for destroying or trashing these apples, or feeding them to pigs, chickens or other animals, is to reduce sites for the codling moth to hide over the winter. Their larvae are the worms (actually caterpillars) we often find inside apples. With them comes their brown disgusting frass (a mixture of feces and food fragments), which aesthetically ruins many an apple or pear. Larvae overwinter in silky cocoons under loose bark, in the soil or in debris (including old fruit) under the tree. Come spring, they change into adult moths, each ready to lay 30 to 70 eggs on leaves, bud spurs and fruit. Once the eggs hatch, the wormlike larvae bore into the fruit. Eventually they drop out of the fruit to start the process all over again.
Managing codling moths can be difficult. Preventative measures are important. Don’t allow populations to develop over a season or two because it is easier to manage infestations when populations are low. Get rid of all fruit as it falls, because sanitation is the first line of defense. Don’t leave fruit on the tree over winter. Check the fruit as it grows, starting six to eight weeks after bloom and eliminate the fruit showing signs of worms. This will help keep the numbers of moths down. If you are considering planting apple or pear trees, try to find varieties that are less susceptible to damage by choosing early-maturing ones.
If there are apple or pear trees near you, and your neighbors aren’t controlling their moths, you may have to resort to pesticides. There are both organic and traditional pesticides available. Timing of application is critical. For more information, see the University of California, Davis fact sheet at www.ipm.ucanr.edu/PMG/PESTNOTES/pn7412.html.
JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at skellyj@unce.unr.edu.