My neighbor asked me why her squash seemingly died overnight. Unfortunately, I had to tell her about squash vine borers (SVB). If you grow squash in Central Texas, you are most likely familiar with this insect and it’s damage. If you have not yet had the pleasure of encountering SVB, either lucky you or welcome to Texas or welcome to vegetable gardening!
Squash vine borer refers to a moth that lays reddish-brown eggs singly on the base of squash plants. When the eggs hatch, the larvae bore int
o the squash stem where they feed on the plant from the inside. So if the insect is on the inside of the plant, how can you tell if that’s the problem? Typically, there is a hole in the stem where the larvae entered which has yellow sawdust-like frass coming out of it. Larvae overwinter in the soil, pupate, then emerge as adults in the spring to mate and lay eggs. Adult moths are about half an inch long with bright, contrasting colors. The abdomen is bright orange with black dots. The front wings are a greenish-black color and the hind wings are clear, but you typically don’t see the hind wings as the wings are folded over the back when at rest. Damage is death of the squash vine. Usually it starts at the base of the plant and moves towards the outer parts.
If you have had squash vine borers infest your squash, vines should be removed and destroyed (not composted unless you are sure your compost pile temperature reaches high enough to kill insects) soon after squash harvest. Soil can be tilled before planting to reduce the number of larvae that are in the soil. Row cover can be used to protect new crops of squash you may plant, just remember to remove the row cover when the squash has blooms to allow pollination to occur (or hand pollinate). If you leave the squash uncovered, monitor the stems regularly for eggs and squish the eggs before larvae emerge.
You can also try to remove the borer from the stem before too much damage occurs if you catch the infestation early enough. Slit the stem lengthwise with a sharp knife, remove the borer and then cover the cut stem with moist soil and hope it takes root. Some people may have better luck with squash varieties that root wherever they touch the ground.
On another note, have you been tuning in for the All Bugs Good And Bad FREE webinar series? If you missed one (or all for that matter), you can still listen and get great information!
Here’s a link to all of the webinars for 2015.
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