MEEKS: Plum curculio are tough pests to fight

Because these nasty buggers keep showing up in my office, I decided to do a whole article dedicated to them. The plum curculio original native hosts included wild plum, crab apple, cherry, and other similar plants. Now it enjoys our delicious array of peaches and other stone fruit of the Southeast. It is also a pest of pome fruit and blueberries.

Adult plum curculios are small brownish-black snout beetles, about a quarter of an inch long, molted with lighter gray or brown markings. The larvae are slightly curved, yellowish-white, brown-headed grubs, about 3/8 inch long when fully grown.

Plum curculio overwinters as an adult in ground litter in and around orchards. They become active when the average temperature reaches 50-60 degrees for three or four days. They begin moving toward orchards when the temperature reaches 70 degrees for more than a couple of days. They are reluctant fliers in cool temperatures, so if the temperature is under 70 degrees, they walk to the orchard. This temperature event usually takes place shortly before or as peaches bloom. Initially, adults feed on buds, foliage and blooms.

Both adult and larval stages of the plum curculio damage the fruit. On plums and nectarines, adults cause tiny circular feeding punctures or small crescent-shaped oviposition wounds adjacent to egg-laying punctures. On peaches, it is common to see a 1/8 inch of shiny fuzz. Teasing away the fuzz will expose a feeding or oviposition scar, possibly an oval white egg or brown larval tunnel into the flesh. These feeding and oviposition sites cause conspicuous scarring and malformation as the fruit develop and can provide entry for the brown rot fungus.

Most peaches infested by the plum curculio early in the season will drop prematurely. Female curculios will deposit eggs whenever fruit is available. Large peaches, infected after pit hardening begins, generally stay on the tree, but they are infected with worms and are of no value.

Plum curculio control programs are intense. Keeping the orchard floor closely mowed after harvest provides less protective cover to adults that overwinter in the orchard.

Destruction of nearby wild plum thickets, abandoned peach blocks, and other alternative hosts is suggested to reduce plum curculio migration into orchards from outside sources.

Adult populations are suppressed in the spring by well-timed applications of effective insecticides. Sprays provide a protective barrier to prevent overwintering adults from laying first generation eggs.

Sprays for plum curculio control are normally initiated at shuck split. Additional sprays may be needed to assure control of overwintering populations. Follow labeling directions.

Thanks to the last client who brought me a bag of gnarled up plums and peaches, I officially have one preserved in a jar of alcohol if you would like to view a plum curculio up close and personal.

Source: www.caes.uga.edu/publications/ Plum Curculio, Donn Johnson, Dan Horton, Russell F. Mazell III

DATES TO REMEMBER

May 25: Office closed for Memorial Day.

For more information on any program area, contact Houston County Extension at 478-987- 2028 or drop by our office in the old courthouse, downtown Perry, 801 Main St. Office hours are 8 a.m.-5 p.m., Monday through Friday. Visit our website at www.caes.uga.edu/extension/houston for more news about your local Extension office. Check out my blog at www.blog.extension.uga.edu/houston.

This story was originally published May 13, 2015 at 12:00 AM with the headline "MEEKS: Plum curculio are tough pests to fight."