| Special to The Gleaner
Summer gardens in Kentucky would not be complete without summer squash. Yellow straight neck, acorn squashor zucchini —all are a staple in our garden and produce prolifically throughout the season. Some insects like to feed on summer squash, however, and there is no worse insect than the squash vine borer.
The squash vine borer shows up as a ½ inch long moth with an orange body lined with black dots. They fly around during the day and lay eggs at the base of the plants. In about a week, the eggs hatch producing a white larvae that bore into the stem of the plant to feed. This is where the problem starts.
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As the larvae feed inside the stem, they produce a sawdust like waste called frass. The stem gets clogged up with the larvae and frass and prevents water flow to the rest of the plant. If the plant can survive, larvae will feed for several weeks before exiting the stem and burrowing into the soil to pupate for the winter. It typically doesn’t take long for the plant to wilt, collapse, and eventually die.
Squash vine borer control can be challenging. After the larvae enter the stem, they are difficult to treat with insecticides. Best practices focus on control before that happens. Watch for the moth activity early in the season. The moths can see easily seen and heard (they make a loud buzzing sound when they fly).
You also can use a yellow container of water to monitor activity; the moths are attracted to yellow and will fly into the water. Begin monitoring in mid June.
Once you have identified the moths in your garden, you have a few options. Row covers will prevent the moths from laying eggs near the squash. Keep the covers on for at least two weeks after you first identify the moths. Make sure to secure the bottom to prevent the moths from getting in. Don’t use row covers if you planted squash the previous year, however. The larvae are likely in the soil and row covers will not help.
Insecticides such as carbaryl, permethrin, or bifenthrin are effective if you spray or dust at the base of each plant. Continue treatments every 7-10 days until the end of July. If your squash is still attacked, you have one last option. Look for the frass on the stem and carefully slit stem from base upwards until you find and remove the larvae. Cover the wounded stem with soil and keep moist. It should form roots around the wound.
It is always a bad day when I find a wilted squash plant in the garden. Remember to rotate your crops and always select varieties that have built in resistance. If you do apply a pesticide, always follow the label. If you have questions about squash vine borer, give us a call at the Henderson County Extension Office; we are happy to help!