It was my first season gardening. The large, deep green plants held dozens of yellow babies. Just a few more days and we’d be feasting to my mom’s favorite southern dish — fried squash.
Then one day, I walked out in my garden and an entire plant’s leaves were drooping. I had no idea what was going on! Perhaps it needed water? (But we had plenty of rain.) Perhaps it was just too hot? (Then why were the others perfectly fine?)
The next day I went to the garden again and this time the plant was dead. Just like that.
Soon afterward the others succumbed to the same fate.
What went wrong?
After doing some research I realized my squash plants had been afflicted by the squash vine borer. I had never heard of it, but I quickly realized my squash and zucchini harvests every season since would depend on three things: prevention, identification, and control.
Prevent the Squash Vine Borer
While you can’t prevent the adult squash vine borer moth from seeking out your prized zucchini plants, you can take actions to prevent her babies from killing them.
First, rotate your crops each season. Squash vine borer grubs overwinter in the soil and the adult moth emerges to lay eggs and complete the cycle.
Second, as soon as your squash, zucchini, or pumpkin seedlings emerge, cover them with floating row covers to prevent the moth from landing on them. Make sure to uncover the plants when flowers appear, as bees need access to pollinate the flowers.
Third, wrap stems of the plants with aluminum foil or gauze strips. When the eggs hatch, the grubs immediately bore into the stem. By covering the stem, you can prevent them from finding their way into your plants.
Although all of this advice should help with your borer problem, you may find it too labor-intensive, especially if you plant several plants. My best advice is to plan a late planting, which will skip the borer’s life cycle altogether. I plant early crops but I plan for them to succumb eventually. Then I plant a late crop around the end of July, and I’ve never had a problem with the borer. In fact, my best squash and zucchini harvests come with this late planting!
Identify the Squash Vine Borer
The adult squash vine borer moth lays eggs at the base of squash, zucchini, or pumpkin plant.
Begin inspecting the base of your squash, zucchini, and pumpkin stems. The squash vine borer eggs can look like dirt, but if you’ll look closely, you’ll see a copper-colored round egg. Scrape it off and dispose of it.
If you don’t catch these eggs, they will hatch into an ugly little grubs that burrow themselves inside the vines, where they begin eating the plant from the inside out. The first sign of borer damage is telltale yellow sawdust-like frass on the vines.
When you notice that frass, the death of the plant will soon come unless you intervene.
Control the Squash Vine Borer
Once afflicted, the squash plant will continue to suffer damage from the grub eating its way from the inside out of the stems. If you can catch it early, and if your plant is healthy and vigorous, you can dig the grub out.
I explain more about this “surgery” in the video below:
While this icky process can save the plant, I have found that if they do recover, they don’t produce as well. Sometimes, with a severe infestation, the plant doesn’t recover at all.
But I’ve found if I can catch the borer’s activity early, and the plant is healthy and vigorous, the damage will be less severe.
I have tried injecting the stem with organic pesticide (Bacterial Thurengensis), but it did not work for me. It’s worth a try though! I’ve also heard of people taking needles and puncturing the vines where the squash vine borers are likely to be (based on the trail of frass). This would effectively kill the grub in the stem without having to slice open the plant. I think this would be worth a try as well.
The bottom line for my garden is this: the borer is just an enemy I have to deal with as best I can. And a big key to my success in squash and zucchini is multiple plantings. With a long season like ours (frost-free from March 31 – November 15), I usually plant three different plantings (one in early April, one in mid-June, and one in late July). Not only does this give us squash and zucchini for most of the summer and fall, but when I eventually lose the plant when I’m unable to keep up, I’ve got another crop on its way.
Have you had success controlling the squash vine borer?
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