Surgery for the Worst Garden Pest
Everything is going along well in your garden. Your zucchini and pumpkin plants look like they could take over the world and then one day you look out the window and see the plants wilting a bit in the mid day heat. You quickly water the plants and by evening they have recovered. The next day same thing. What could be going on since you know they have been watered? It is likely the work of my personal nemesis, the squash vine borer. A brightly colored black and red/orange moth that lays eggs on the stem of your healthy squash plants. The eggs hatch into caterpillars that burrow into the stem eat your squash vines from the inside out, damaging the plants ability to take up nutrients and moisture from the soil.
What can you do? I have never had complete success with prevention. I’ve tried covering the plants with a lightweight insect barrier until they bloom. This is easier said than done since they grow so fast. This year the birds also decided this lightweight fabric would make a lovely addition to their nests and I caught them tugging off bits of the fabric until it was in shreds. I’ve tried the tin foil around the base of the stem. I think they just moved up to a higher point on the plant to lay their eggs. I’ve tried planting a trap crop (a plant they are supposed to prefer more than my zucchini and pumpkins) but I got it in a bit late.
You may get lucky if the vines have rooted at additional places as they grow (you can even encourage this by mounding some dirt over the vines in a few places). If prevention hasn’t worked your only choice is to take drastic measures. By that I mean squash vine borer surgery. Here is what the stem looks like when vine borers are present. You can see something that looks a bit like sawdust on the stem.
Take a knife and cut a slit in the vine. I usually cut out a long thin diamond shape.
You may be afraid to damage the plant but really you have nothing to lose. The plant is going to die anyway if untreated (unless you’ve been able to get it to root somewhere else along the vine). Often I find that the vine is already eaten away on the underside. No wonder the poor thing is wilting every day! Once you have the stem opened up, you go in with your tweezers, searching for the caterpillars.
You may have to reach up inside the vine or cut further into the stem. If you are lucky you will snag a caterpillar or two.
Yes, they are gross! Then cover up the wounded vine with moist soil and hope for the best.
This year I have removed several vine borer caterpillars from my zucchini and pumpkins (I lost count after 8). So far the plants have survived and some are even producing. Mainly, I have a lot of male blossoms so I watch vigilantly for any female blossoms and help nature along.
Be sure to discard any dead vines at the end of the season and do not compost them if they had squash vine borers. I’ve read that you can actually see the eggs laid on the stem, usually at the base of a leaf. Next year I’ll try to search for them when I’m out with my duct tape removing the other squash bug, uhg!
I may just try covering up the stems with duct tape-it’s worth a try!