The squash vine borer is a key pest that attacks summer squash, winter squash, gourds, and pumpkins. Their damage is usually not noticed until it is too late. The squash vine borer overwinters in cocoons in the soil, usually in the area of the garden where squash or pumpkin plants were located the previous season. Adult moths begin to emerge from the soil about the time the plants begin to run, and moth flight continues through mid-August.
They lay small brown eggs individually on leaf stalks and vines. The newly hatched larvae immediately bore into the stem where they will feed for 14 to 30 days before exiting the stem to pupate in the soil and start the life cycle over again. The squash vine borer doesn’t seem to attack cucumbers and melons as much as squash, gourds, and pumpkins.
The best method for controlling the squash vine borer is to rotate your garden crops from one area to the next. When you rotate your squash plants to another area from the previous year’s area, you are taking away the food for the next hatch of borers. This will keep a population of borers from building up in the soil. If rotation is a problem in a small garden, you may want to try floating row covers. They are made of an extremely light-weight woven or sun-bonded synthetic material that allows light and water to penetrate. They should remain on the plants until female flowers begin to form. At this point, the covers must be removed to ensure pollination. Covered plants have a tremendous head start on borers.
Physically removing the squash vine borers is another method of control. Some gardeners have had some success with deworming the vines. Deworming involves keeping a close watch on your plants so that at the first signs of a sawdust like frass at the base of the vines, you can slit the stem lengthwise with a sharp knife near where the damage is found and remove the borers from inside the stem. The stems should be immediately covered with about 1-2 inches of soil. Water them to encourage rooting. Another natural method of control is to use yellow-colored bowls full of soapy water to attract and drown the adults. Still, another option is to use sticky traps, which are also usually yellow and attract the insect. After your final harvest, it is important to remove the vines from the garden and compost them to prevent the remaining borers from continuing the life cycle.
Control by using an insecticide is a method that is safe when used correctly. The key to this method of squash vine borer management is controlling the borers before they enter the stem. Once inside the vine, insecticidal control is ineffective. Products with the active ingredients bifenthrin or esfenvalerate should control the borer if applied on the branch stems and the main vine of the plants. Milder, more natural insecticides that may control the borers are insecticidal soap, neem oil, and Bt products. Insecticides should be applied once every 5-7 days for about two to three weeks.
We are always here to help at the Banks County Extension office. Ways to contact us are to call us at (706) 677-6230, by email at email@example.com, or to come by the office at 413 Evans street, Homer, GA.