PLUM CURCULIO

A, Life stages (greatly enlarged): a, larva; b, pupa; and c, adult. B, Peach "mummy" with larva inside. C, Small apple showing curculio scar. D, Small peach with gum oozing from curculio puncture. E and F, Mature apple and plum showing appearance of curculio scars at time of harvest. (B, C, D, E, and F, natural size.)

PLUM CURCULIO

The plum curculio is a common and serious pest of peaches, plums, cherries, and apples in the States east of the Rocky Mountains. The surface of the fruit is scarred or distorted by the feeding and egg-laying punctures of the adult curculios. The inside is injured by the burrowing of the larvae or grubs. The adults are small, hump-backed, and brownish snout beetles about one-fourth inch long that spend the winter in protected places on the ground in and near orchards. They move to the trees about the time peaches bloom or a little later and feed on the leaves and blooms. They attack the fruit soon after it sets and attack it intensively for about 3 weeks. The feeding punctures are small circular holes. The eggs are laid in crescent-shaped cuts, which the females make in the fruit. Eggs hatch in about a week. The yellowish-white grubs become full-grown in 2 weeks or more. The mature grubs leave the fruit and go into the ground, where they complete their development into adult beetles. Two generations are often completed in the southern range of the insect, but there is only one in the northern range. In an intermediate zone (latitude of Delaware to Virginia) there may be a partial second generation. The second generation develops in maturing fruit. Most of the fruit injured early in the season falls to the ground or is scarred, dwarfed, and deformed. Fruit injured later remains on the tree, but is scarred and wormy.

Control: On apples, spray the trees with lead arsenate, 3 pounds, or with a combination of lead arsenate, 2 pounds, and 50 percent DDT wettable powder, 2 pounds, per 100 gallons of water, (a) at petal fall, (b) 7 to 10 days later, and (c) about 2 weeks later.

On peaches and other stone fruits, spray the trees with lead arsenate, 2 pounds, plus hydrated lime, 8 pounds, or with 15 percent parathion wettable powder, 2 pounds per 100 gallons of water, (a) at shuck split, (b) 7 to 10 days later, (c) 7 to 10 days after (b), and (d) if parathion is used, 12 to 14 days later. In areas where a second brood occurs, spray (a) just after the petals have fallen, (b) when the shucks are shedding, (c) 7 to 10 days after (b), and (d) about 1 month prior to harvest. If parathion is used, put on application (d) 5 weeks before harvest and (e) 3 weeks before harvest.

Do not spray fruits with lead arsenate or DDT later than 4 weeks before picking. Do not spray them with parathion later than 3 weeks before harvest. Scrub or peel sprayed or dusted fruits before eating them. Parathion is especially dangerous to handle; follow all the safety precautions printed on the package.