May is the fun gardening month when vegetable gardens seem to grow overnight! Just this week we have enjoyed fresh lettuce and spinach salads, the last of the Texas Superstar Green Magic broccoli, and a homegrown blackberry cobbler from the garden. The onions are getting close to harvest, and I cannot wait to try out the purple potatoes that I planted this year.
Unfortunately, a few garden pests have also started enjoying the daily buffet found in our garden spot. Warm weather brings out the garden pests, including caterpillars, stink bugs, beetles, aphids, and spider mites. Be sure to monitor your garden frequently so you can stay ahead of pest problems before they damage your garden.
The pest at the top of our minds right now is the squash vine borer (SVB). Most Texas gardeners groan when SVB is mentioned because we all know how quicky it can take a squash plant out just when your mouth was starting to water at the thought of fried squash for supper.
Squash vine borers are a tricky
pest because the tiny caterpillar burrows into the vine before you can really see it. The larval stage of the SVB will burrow into the plant stem or crown and disrupt the water and nutrient flow. The plant will wilt because of the lack of nutrients and water and eventually die.
Adult squash vine borers are moths with bright reddish-orange bodies and black or metallic green wings. They are active as early as April/May in Texas and will remain active until November/December. Adults lay eggs on the leaves and stems of host plants, and the eggs hatch and burrow into the stems. The full-grown larvae actually climb down from the stems and pupate in the soil.
Control of SVB is an integrated approach with a multi-pronged strategy. Sanitation in the garden is an important step. Remove dying or dead vines to ensure that any larvae still inside the plant are gone. Till the soil to expose any underground pupae to the elements and predators. Consider planting types of squash that are resistant to SVB like acorn squash, summer crookneck, butternut squash, and others.
Consider using floating row cover over your squash and zucchini plants to prevent the adult moths from laying eggs on your plants. Remember that you might need to hand-pollinate your squash or remove the row cover during bloom to allow bees to pollinate the female flowers.
You can remove larvae from infested vines by splitting the stem with a knife and carefully pulling out the larvae. The larvae make good fish bait or bird food! You can spot the plants that have been infested by looking for stems with oozing plant residue and frass (caterpillar poop).
Spinosad and Bt (Bacillus thuringiensis) are two organic control options. Spray the stem often to maintain control. Use Spinosad in the evenings when bee activity is done for the day. Carbaryl, permethrin, bifenthrin, and esfenvalerate are chemical control options that are all labeled for SVB. Apply directly to the stems and vines for and repeat weekly fore best control.
I hope your squash harvest is prolific and borer free this summer! For more lawn and garden information, contact Kate Whitney-Hajda at the Williamson County Extension Office at 512-943-3300. Did you know we have a Master Gardener Help Desk? Call us on Tuesdays or Fridays from 10:00am to 2:00pm to talk with a Master Gardener about your garden questions.
