By Keith Mickler, Floyd County agriculture agent. 706-295-6210
Nedua release: Well dadgum, who left the oven door open with the dog gone thing on broil? It sure has been hot; these high temperatures can ruin a respectable looking vegetable garden fast, especially the ever temperamental southern favorite the squash. The main culprit behind the demise of our squash is currently the Squash Vine Borer. This bad mamajama has come on quickly due to these extreme high temperatures. My friends just north at the University of Kentucky have this to say about the sorry ole squash vine borer.
Squash vine borer is a key pest of squash, gourds and pumpkins in the south. Unfortunately, it is usually noticed only after it has done its damage. Symptoms appear in mid-summer (ha, summer just started) when a long runner or an entire plant wilts suddenly. Infested vines usually die beyond the point of attack.
Sawdust-like frass (squash vine borer stinky) near the base of the plant is the best evidence of squash vine borer activity. Careful examination will uncover yellow-brown excrement pushed out through holes in the side of the stem at the point of wilting. If the stem is split open, one to several borers are usually present.
The caterpillars reach a length of 1 inch and have a brown head and a cream-colored body. The adult squash vine borer is a stout dark gray moth with 'hairy' red hind legs, opaque front wings, and clear hind wings with dark veins. Unlike most moths, they fly about the plants during the daytime, appearing more like a paper wasp than a moth.
This insect overwinters as a full grown larva or a pupa one to two inches below the soil surface. The larva pupates in the spring, with the adult moths begin to emerge about the time the plants begin to run, and moth flight continues through mid- August. The small brown eggs, laid individually on leaf stalks and vines, hatch in seven to 10 days. The newly hatched larva immediately bores into the stem. A larva feeds for 14 to 30 days before exiting the stem to pupate in the soil. There are 1 to 2 generations per year in Kentucky.
ManagementThe key to squash vine borer management is controlling the borers before they enter the stem. Once inside the vine, insecticidal control is mostly ineffective but this does leave a slight of hope an insecticide might kick'em it the tail.
Adult emergence occurs at approximately 1000 degree days in the early summer. Use 950 degree days the time to begin monitoring plants (you can monitor this at www.georgiaweather.net) weekly for initial signs of the borer's frass at entrance holes in the stems. This usually corresponds to mid-June ( it's just early June) as the start of the adult flight. Very early signs of larval feeding indicate that other eggs will be hatching soon.
You can also use yellow trap to detect squash vine borer adults. This can be any container (pan, cup or bowl) colored yellow and filled with water. Because squash vine borer adults are attracted to yellow, they will fly to the container and be trapped when they fall into the water. Place traps by late May to early June. Check your traps at least once a day. When you notice squash vine borer adults in your traps you know they are active and it is time to take further action.
Use two insecticide applications (such as bifenthrin or esfenvalerate) 7 days apart to control newly hatching larvae and continue to monitor for additional activity. Sprays need to penetrate the canopy to cover the vines to be effective.
Some home gardeners have had triumphant wins with deworming the vines. At the first signs of the sawdust-like frass, vines are slit lengthwise near where the damage is found and the borers removed. The stems should be immediately covered with soil. Sanitation is also important. After harvest is complete, vines should be removed from the garden and composted to prevent the remaining borers from completing larval development. Burying a few nodes along each vine will encourage rooting at these nodes. This will lessen the impact if squash vine borers girdle the base of the vine.
When all else fails and you can stand it no longer, visit your local farmers market for your squash fix, no one has to know you didn't grow'em, you can even place a few of them bought squash out among your dying plants to help sooth your anxiety.
Keith Mickler is the County Coordinator and agriculture agent for The University of Georgia/Floyd County Cooperative Extension, 12 East Fourth Ave., 706-295-6210. Office hours: 8 a.m.-5 p.m. Monday-Friday. The University of Georgia Cooperative Extension - Learning for Life. Agriculture and Natural Resources, Family and Consumer Sciences, 4-H Youth. An Equal Opportunity/Affirmative Action Institution. To obtain extension publications please visit our web site www.ugaextension.com or contact your county Cooperative Extension office.
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