No one enjoys wormy fruit! The codling moth is the parent of the pesky worm that ruins our homegrown treasures. It is no wonder that keeping our fruit free of worms is such a challenge, considering that one female codling moth can lay 30 to 70 tiny eggs on leaves, bud spurs or fruit. In addition, the moths can sometimes produce multiple generations in a single year.
Successful codling moth management starts by keeping populations small. A combination of nonchemical strategies, judicious use of low-impact chemicals and tolerance of some worms works best. Nonchemical controls include sanitation, mass trapping, trunk banding and fruit bagging.
Sanitation begins as fruit starts to grow. Check fruit every week or two for signs of holes or reddish-brown droppings. Pick these infested fruit and destroy them, and pick up all fallen fruit each day. Both of these practices keep populations low.
Sex-attractant, or pheromone, traps are available to lure males, reducing mates for females. These traps work when trees are isolated from other apple and pear trees. Use one to two traps in small trees, and two to four traps in large trees. University of California, Davis offers this recipe for a homemade trap. Use "a 1-gallon plastic milk jug containing the following: 1 cup cider vinegar, 1Ú3 cup dark molasses, 1Ú8 teaspoon ammonia, and enough water to make 1-1Ú2 quarts of liquid. Cut a 2-inch diameter hole just below the shoulder of the jug. Leave the cap on the jug. Hang the jug in the tree using a wide strip of cloth to disperse the weight of the jug and protect the tree branch. As an attractive food source, this trap will capture both male and female moths. While research is not available on the effectiveness of these traps, backyard gardeners have reported success with this method. You can use up to three of these bait traps per large tree or you may want to use both bait and pheromone traps in the same tree to maximize capture."
In addition, a 4-inch-wide corrugated cardboard band can be wrapped around smooth-bark trees 18 inches or more from the ground to trap mature larvae as they seek a place to cocoon, or pupate. Leave the band on for about a month. Then remove and destroy the bands and any pupae you see left on the trunk. You can re-band the tree late in the season to catch the overwintering generation.
Bagging fruit is tedious, but it works quite well. Enclose fruit that are from 1Ú2 to 1 inch in lunch-size papers bags while they are on the tree. Cut a 2-inch slit in the bottom of each bag, slip it over the fruit, and staple shut the open end of the bag. Pruning trees to a height where the canopy is easy to reach will also facilitate your nonchemical management efforts.
For additional information on preventing worms from eating your tasty, homegrown fruit, go to http://www.ipm.ucdavis.edu. For more information on gardening, contact me, 887-2252 or skellyj@unce.unr.edu, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" by e-mailing mastergardeners@unce.unr.edu.
• JoAnne Skelly is the Carson City Ú Storey County Extension Educator for University of Nevada Cooperative Extension.