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The squash vine borer is a clearwing moth common east of the Rocky Mountains. It is a serious pest of vine crops, usually attacking summer squash, winter squash and pumpkins. Cucumbers and melons are less frequently affected. In home gardens entire crops may be lost in a year of high borer populations.

The adult borer frequently mistaken for a wasp has an orange and black striped abdomen and metallic green clear wings. Beginning in late June or early July the borer lays flat brown eggs singly at the base of plants. About a week after they are laid the eggs hatch and the larvae bore into the stem of the plant to feed. The larvae, white or cream colored caterpillars with brown heads, feed through the center of the stem blocking the flow of water to the rest of the plant. The larvae feed for 4-6 weeks then exit the stem and burrow into the soil to pupate.

Wilting of affected plants is usually the first symptom of borer attack. Wilting may occur only in strong sun at first but if the problem is left unchecked the plant will eventually collapse and die. Close observation of a wilting plant should reveal holes near the base of the plant filled with greenish or orange material which looks like moist sawdust. In time the base may become mushy or rot away altogether. Several borer larvae may attack a single plant.

Squash vine borers are difficult to prevent or control but there are several procedures that can minimize the damage. Planting resistant varieties, such as Waltham butternut squash, should help to minimize losses. A second planting of summer squash early in July will mature after the adult borers have finished laying eggs for the year.

Using light-weight row cover fabric to keep the adult borers from reaching the plant may help. Drape the fabric (usually spun polyester) over the plants and secure the edges with soil or sod staples. Keep the covering in place several weeks until the adult borers are gone.

One problem with row covers is that they also prevent bees from pollinating flowers. Male and female squash flowers grow separately and require a pollinator for proper fruit set. This could be an issue with winter squash and pumpkins because the fruit must set early to have time to mature before frost.

You can treat the base of susceptible plants with methoxychlor or endosulfan (thioden) or you may use carbaryl (sevin). Carefully dust or spray the lower stems with the pesticide through the end of July at weekly intervals. Carbaryl is very toxic to bees so avoid dusting or spraying it on or near the squash flower.

A method that some growers use successfully is to mound a small amount of soil at every third or fourth leaf junction as the vine grows. This will encourage the plant to send down new roots at these points, so if the borers attack the plant can still uptake moisture.

If all else fails you can do an early surgery that may save your crop. As soon as wilting is noticed use a sharp knife to cut a slit into the affected stem. Slice carefully up the vine until you locate the borers. Once you have killed any borers with the tip of your knife, mound moist soil over the cut area and keep this spot well watered. New roots may grow along the cut stems allowing the plant to survive. Plants killed by the squash vine borer should be promptly pulled and destroyed.

Upcoming Classes

July 14, 6:30-8 p.m.––Ornamental Grasses

Fairview Lakes Regional Health Care Center in Wyoming. Cost $4. Please call the office to register. 651-674-4417.

For information on upcoming topics in the "Summer 2005 Flowering Gardening Series" and how to buy tickets, call or stop by the Chisago County Extension Office, 38780 8th Ave, No. Branch, or visit our website to download a ticket order form: www.extension.umn.edu/county/chisago.

July 26––FREE CLASS

Dave Hanson, Trees, Trees, Trees, 6:30-7:30, at the Senior Cente, in North Branch. We receive more questions on trees than any other topic. Come learn about selection, planting and care, pruning, diseases and how to contact an arborist. Dave is a Research Specialist and Tree Care Advisor Coordinator, Urban and Community Forestry, University of MN, Department of Forest Resources. If he doesn't have the answer to your question, he will know who does! The Senior Center is located at 6th and Maple St. Enter through the double glass doors from the parking lot side of the building.

In Your Yard and Garden

Master Gardeners will be at the county fair this week. Our booth is located in the restored log cabin building on the southwest corner of the fairgrounds. Bring your samples and questions, or just stop by to say hello. Be sure to pick up a brochure that lists the services we offer and the class schedule for the remainder of the summer.

Ways to access information:

Master Gardeners will be offering free plant clinics every Monday night, from 4:30-8 p.m., at the Extension office in North Branch. Stop by 38780 Eighth Ave. (the Anderson Chiropractic Building) or call 651-674-4417 to speak with a Master Gardener. During the rest of the week, you can leave a message and a Master Gardener will return your call.

You can also click on 'Ask a Master Gardener' next to the cute little flower on the right hand side of the page. Here you can search 1000's of answers from Master Gardeners around the state. If you don't find your answer you can submit a question online or search for University publications.

Bell Museum of Natural History

For information about snakes, skunks, raccoons or other wildlife around your yard, call the wildlife information line at (612) 624-1374 or www.bellmuseum.org

To see the latest Yard and Garden newsletter, go to: http://www.exten sion.umn.edu/yardandgarden/YGLNews/YGLNews.html.

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