CORVALLIS, Ore. — The codling moth may be the most damaging insect in home orchards of apples, pears, plums and walnuts. The most common control method used by home gardeners is repeatedly spraying insecticides on the fruit throughout the growing season.
But several other less toxic control methods are available.
Codling moths begin to emerge when apples are in bloom, usually in May or June. The adults are small, with a wingspan of roughly 3/4 inch. The wings are gray-brown with lighter gray lines and golden or bronze areas near the wing tips. The caterpillar, or "the worm in the apple," is about 1/2-inch long, white with a pink hue and a brown head.
Newly hatched larvae bore into fruit, feed for about three weeks, then leave the fruit to pupate on the ground or on the tree trunk and emerge as adults the following spring. The spring adults lay eggs on developing fruit that will develop into a second summer generation. Depending on location and length of the growing season, two to three generations can occur each summer.
The traditional control program is to spray trees with insecticides. But if you prefer to use softer control methods, the following tactics can reduce codling moth damage.
Pheromone lures and traps
Pheromones are compounds emitted by female moths to attract a mate. Synthetic pheromones, laboratory-made compounds, mimic their natural counterparts.
Codling moth traps are cardboard or plastic structures (search for Delta trap or Wing trap) baited with a commercially available lure and equipped with a sticky bottom. Male moths are attracted to the pheromone and get stuck in the glue. Traps should be checked regularly for moths. Catching moths provides information on moth flight activity and indicates when you need to protect fruit. Applying pesticides only when it is necessary can help reduce the number of sprays needed. In backyard settings, with just a few fruit trees, traps can often attract and kill most of the males, significantly reducing mating.
Sanitation and banding
Sanitation is the one of the most important practices for reducing pest populations and preventing fruit injury to you and your neighbors. By removing and disposing of damaged fruit throughout the season, you can help reduce future generations. Scout for injured fruit during the growing season and remove fruit promptly before the larvae finishes developing. Larvae can continue to feed inside the fruit after it falls from the tree so cleaning up fallen fruit can also reduce insect populations.
Mature larvae drop from the fruit by a silken thread and look for a place to pupate, often crawling back to the tree trunk and spinning a cocoon on the bark of the tree. Installing tree bands (strips of cardboard wrapped around the tree trunk) provides the larvae with an ideal hiding place. Cardboard bands, filled with codling moth larvae, can be collected and destroyed a couple times a year, to help control populations without any pesticide. Larvae sometimes pupate in the leaf litter on the ground, so keeping the ground under the tree clear of weeds and grass will improve the effectiveness of the banding technique by eliminating other pupation sites.
Bagging
Although time-consuming, bagging developing fruit in screen mesh bags can be an effective method of preventing insect damage in backyard trees. Commercially available mesh bags can be tied onto developing fruit soon after the flower petals fall off.
Resources
Several resources for pest management are available from OSU. An OSU Extension Service publication, "Managing Diseases and Insects in Home Orchards," is available online.
The Pacific Northwest Insect Management Handbook also has up-to-date information on many insect pests.
¡Use los pesticidas con seguridad!
- Póngase ropa de protección y equipo de seguridad según las recomendaciones de la etiqueta. Báñese después de cada uso.
- Lea la etiqueta del pesticida—aunque lo haya usado antes. Siga al pie de la letra las indicaciones de la etiqueta (y cualquiera otra indicación que Ud. tenga).
- Tenga precaución al aplicar los pesticidas. Conozca su responsabilidad legal como aplicador de pesticidas. Usted puede ser responsable de heridas o daños resultantes del uso de un pesticida.
