THE PICKLEWORM

A, Life stages; a. larva; b, pupa: and c, adult. B. A small part of a squash vine showing complete destruction of crop and damage to vine; d, feeding holes in flower buds, stems, and fruits. (All natural size.)

THE PICKLEWORM

The pickleworm is a serious pest of squash, cucumber, and muskmelon in the South Atlantic States and Gulf Coast States. It frequently causes considerable damage in adjoining States and occasionally occurs as far west as Texas, Kansas, Missouri, and Iowa and as far north as the tier of States extending from Illinois eastward to Connecticut. Summer squash is its favorite host.

The pickleworm is active throughout the winter in extreme southern Florida, where its cultivated or native hosts are continuously available. From this and similar subtropical areas the insect gradually spreads northward each year, usually appearing later in the spring than most insects.

The eggs are laid singly and in small clusters among the hairs on flower and leaf buds, small fruit, and young leaves. They hatch in about 3 days. The young pickle-worms feed on the surface of the areas where the eggs are laid, but soon tunnel into and mutilate flowers, terminal buds, stalks, vines, and fruits. The fruits are made unfit for food and the plants are injured or killed. The pickleworms mature in 6 to 28 days and pupate in partially folded leaves or in trash under the plants. The pupal stage is from 5 to 31 days.

Control: It is not easy to prevent pickle-worm injury. In some areas damage can largely be avoided by planting susceptible crops as early as possible in the spring.

Early and frequent application of an insecticide is necessary when susceptible crops, especially squash and cucumber, are grown in the summer and fall in areas where the pickleworm is abundant. The larvae must be killed before the), enter the fruits. A satisfactory control program free of the hazard of poisonous residues and off-flavor has not been developed.

Weekly use of the fungicide zineb for disease control will aid in the prevention of pickleworm injury. Beginning when the pickleworm first shows up, which may be within 2 weeks after a crop is seeded, apply at weekly intervals a dust containing either 1 percent of lindane or at least 50 percent of cryolite. Use 15 to 25 pounds per acre application or 1 to 1 1/2 ounces to each 50 feet of row. Lindane should also give adequate control of cucumber beetles and the melon aphid and be of value against the squash vine borer.

Lindane and cryolite are poisonous. Do not apply them on any part of the plant that is to be marketed or used as food unless it is known that the residue will be adequately removed by washing, brushing, or other means. Use of lindane until harvest may impart a slight off-flavor to the fruits. Until additional information is obtained on the effects of lindane residues in the soil, do not use lindane in fields to be planted to potatoes or other root crops.

At least partial control can be obtained after fruits appear by weekly use, at a rate of 20 to 30 pounds per acre, of a dust containing either 1 percent of rotenone, 20 percent of sabadilla, or 0.3 percent of pyrethrins (0.2 percent if impregnated form). These materials will be more effective if preceded by applications of lindane (before the fruits appear) and accompanied by use of zineb.