This morning I noticed my zucchini plants had wilted. Watering didn’t help; they stayed wilted. This is the first sign of squash vine borer infestation. The moth that I saw on the plants about 3 weeks ago must have laid eggs on the stems. That would mean the larvae are now present in the stems causing the wilting by sucking the life out of my plants.
This is one of the more difficult pests to control. Chemicals rarely work in killing the bug, and I prefer not to use them anyway. Besides being bad for me, they also are bad for the pollinators that visit the plant. So, what to do? I can try cutting into the stem on it’s axis and try to find and remove the larvae and cover the stems with soil, but that hasn’t worked well in the past. Unfortunately the best thing to do is to pull out the plant before the larvae has a chance to hatch and burrow into the ground to return next year.
In anticipation of the borer, since it’s come every year for the past 10 years, I started a second crop of plants in pots. I transplanted them into the garden last week. They should be fine because they sprouted after the period when the moth lays eggs. Now if only they can grow fast enough to produce zucchini before the frost.
The next day the plant was still wilted so I decided to cut open the stem and see if I could find the bug. I made about a six inch slit with a sharp knife. I couldn’t see a bug so I scraped out that entire section of the stem and trimmed off the dead leaves. I buried the cut section of stem under a mound of compost. Unfortunately that sent the plant into shock and it stopped producing flowers.
It’s a week later now and the plant has perked up, is no longer wilted and seems ok. Perhaps I actually killed the bug.
It’s five days later (Aug. 15th) and the plant looks well. It’s growing again and shows no sign of wilting. It has probably developed new roots where I buried the cuts.
I wasn’t expecting this to work and am surprised that it did. My backup crop of 4 young zucchini plants are also doing well. If it stays warm I’ll have more zucchini than I know what to do with!
August 17th: The plant has resumed production. There were both male and female flowers this evening. This is the first time I’ve ever been able to save a plant. Perhaps it’s because I cut the section with the bug very early at the first sign. In the past I’ve always waited until there were signs of damage on the stem and by that time the plant was too sick.