How to handle the bugs who love cucumbers

Q: Each year I plant cucumbers, both plants and from seeds. The plants grow fine until I pick the first cucumbers. Soon after I pick, the plants start to wilt and die. This starts at the bottom of the plant, and in a matter of weeks the plants are dead. I have tried planting in different spots of my yard. I have tried planting in five-gallon pots with soil that I got from a nursery. The same problem occurs. I have planted string beans in the same spots and they were just fine yielding plenty of beans. Any thoughts you have will be greatly appreciated.

James Marouchoc,

Allentown

A: Cucumbers are members of the cucurbit family (muskmelon, cantaloupe, watermelon, squash and pumpkin as well). While they are susceptible to mildews, wilts and other fungal diseases, the most common problems come from insects. The likely suspects are the cucumber beetle and squash vine borer. Both can produce the symptoms that James has experienced in his garden.

Cucumber Beetles: Cucumber beetles, both striped and spotted, are common pests and important for the diseases they carry as well as the actual damage the insects do to the plant. The beetles are yellow-green with three black stripes or 12 black spots; the grubs are white. These beetles often carry mosaic virus and bacterial wilt. Adults winter over in garden plant debris or weeds. Emerging in early spring, the beetles feed on young plants, attacking the leaves and stems. The females lay orange-yellow eggs at the base of the stem or on the soil near the plant. The grubs emerge and eat the plants, particularly the roots below the soil line. Vines become stunted, wilt and often die.

The first defense is row covers. These lightweight fabric barriers must be secured and exclude the beetles. The covers should be installed immediately after transplanting or as soon as seedlings emerge. However, unless you plant a self-pollinating variety, the cover must be removed when the vines flower to allow insects to pollinate the flowers.

Hand picking the first arrivals is another option. Look for the adult beetles in the flowers. They are easiest to hand pick in the heat of the day by netting them as they fly above the plants. Check regularly for clusters of eggs on either side of the leaf as well as at the base of the stem. Destroy eggs by crushing.

Insecticides are available that target the cucumber beetle. If necessary, use as instructed only after you have properly identified the insect.

Squash vine borers: Though the name says squash, these borers are a frequent problem in cucumbers as well. Identification and control of this pest was covered in detail a few weeks ago (March 6).

Identify the most damaging life stage of the pest by looking at the base of the vine for a small entry hole and sometimes some material resembling sawdust on the ground. Slitting the vine will usually reveal more crumbly material and a fat white grub with a brown head. Remove the grub, carefully close the slit and cover the damaged area of the vine with soil.

The eggs are small clusters of flat brown dots about the size of a pencil point and are located at the base of the plant. Remove and destroy eggs regularly throughout the season. Insecticidal soaps also can help control eggs.

Adults resemble wasps with green metallic front wings and transparent wings with black or brown veins and margins on the rear wings. The body is orange and black, often in a ringed pattern. Some gardeners suggest row covers to keep out adults. This has two drawbacks: soils infested with pupas will allow adults to emerge inside the row cover and row covers must be removed to allow insect pollination.

Control by clearing beds of infested plants and all plant debris at the end of the growing season. Pupas are black and in the soil. Stirring up the soil in the fall and spring can expose pupas to the elements and hungry birds.

Other options: If gardeners have problems with cucumbers despite following good preventive practices, they should consider seeking out resistant varieties. Select plant varieties that specify resistance to mosaic resistance, powdery mildew and other problems.

In the garden

The first package of plants arrived this week -- a box of Aquilegia 'Barlow Mix' ordered last year. My sister Peg and I planted a lot last fall and I've still got a stockpile of plants still in pots, so I've controlled my spring orders. As I'm finally getting over the flu, I'm looking forward to getting out in the garden soon.