The worms don't eat much, and they only damage a small part of the apple yet they are such a big turn-off to the apple eating public. What's up with that?
"My theory is, we don't want to eat worms in our apples because they don't have a fancy name yet," says Jerry Goodspeed, Utah State University Extension horticulturist. We eat fish eggs, snails, fungus, bacteria and even rotting milk, but we give them fancy names such as caviar and yogurt.
"Maybe we could learn to appreciate apple worms if we just gave them a name with a little more flair. How about ‘protein-enriched, aerated apples?' Still not interested? For now, we are stuck with their real name - codling moth."
The codling moth causes wormy apples, Goodspeed explains. This moth emerges in the late spring, and lays its eggs on the fruit or leaves of unsuspecting apple and pear trees. The female moth normally lays her eggs about three weeks after the tree is in full bloom. Once the eggs hatch, the larva crawl around awhile and eventually enter the fruit, working their way toward the center of the apple.
"I don't like applying a lot of sprays but, as I mentioned earlier, worms are not on my list of preferred food additives," he says. "As a result, I have helped in the development of a program that keeps about 80 percent of the apples worm-free, and greatly reduces the frequency of spraying."
Begin this worm prevention program by contacting your local USU County Extension office to find out the optimum spraying date - when the female codling moth first begins laying eggs, Goodspeed says. Imidan is a good chemical choice because it stays active for almost three weeks. Malathion and Diazinon are also registered for this purpose. However, Malathion is only active for 5 to 7 days, and Diazinon for 10 to 14 days. When using any pesticides, be sure to read and follow all label instructions. Before buying any product, make sure apple trees are listed on the label.
The first cover spray needs to be active for about three weeks to protect the apples during the first generation of codling moths, he explains. In June, some apples will drop off the tree. Pick this fruit up and throw it all away. Some may be falling off because of codling moth damage. Don't leave it on the ground or it can become a pupating location for the next generation.
This first cover spray should control the first, and most important generation, Goodspeed continues. The next generation usually emerges and begins causing damage between the first and middle of July. At that point, apply a second cover spray (around the 4th of July). Again, check with your local USU Extension office to get a more definite spraying date.
After spraying for the second generation, continue spraying until early to mid-September, he says. This means applying a spray about every three weeks, if using Imidan. More frequent spraying is necessary with the other chemicals mentioned.
In a normal year with this method, I can limit spraying to three to four times throughout the season, and keep at least 80 percent of the apples worm-free, Goodspeed says. For the other 20 percent of the fruit, I am currently developing a gourmet name so I can put it on the market.
For more information, contact your local USU County Extension office.
Utah State University Extension does not discriminate on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, or marital or family status in employment or program delivery.
Issued in furtherance of Cooperative Extension work, Acts of May 9 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Bonita Wyse, Acting Vice-President and Director, Cooperative Extension Service, Utah State University, Logan, Utah. (EP/06-2001/DF)