Squashing the Vine Borer
Each summer, I go all in on finding solutions to one of my garden enemies. Last year, I built a hawk habitat in a desperate attempt to gain control over my number one enemy: the squirrel. Those little terrorists are still around, but the only major damage they caused so far this year was accidentally Chelsea chopping my sunflowers. Maybe they’ve uncovered my plot to use sunflower seeds to attract small birds, which attract hawks, which eat squirrels…
I turned my attention this year to another nemesis: the squash vine borer.
The squash vine borer is one of those frustrating pests that destroys plants without taking any joy in the most delicious parts. Cucumbers, melons, pumpkins, and zucchini are a few of the plants that I have had decimated by the squash vine borer. Irritatingly, you learn you have squash vine borer when you walk outside one day to see your five foot tall, thriving, flowering plant has become a wilted string of limp leaves.
Destruction from the squash vine borer comes when it, as its name implies, bores a tiny hole into the stem of your plant to lay its eggs. When the eggs hatch, the baby borers consume the stem, cutting off your plant’s access to its roots. With no way to drink water, your plant dies and you become sad.
I tried a few different tactics to curb the borers. When I first discovered their destruction, I used crop rotation to put plants in a different, unaffected area the following year. This didn’t work. Then I tried monitoring leaves for vine borer eggs with little success.
Last year, I monitored growing degree days, which, in short, is a measurement of the accumulation of temperatures above 50 degrees (see how to calculate it here). The life cycles of plants and insects in a garden can be accurately predicted using certain growing degree days because warm or cold weather signals the right conditions for the organism to survive.
Squash vine borers are most vulnerable when in their moth stage prior to egg laying. This occurs in the 900 to 1100 growing degree day window. During this window, I applied Bacillus thuringiensis (commonly known as Bt because it’s hard to pronounce and even harder to spell), a naturally occurring bacteria that functions as a pesticide to certain insects.
I had moderate success with this, but I didn’t think it was a long-term solution I could use every year. Summers where I live can be rainy, and the Bt only works while it’s not washed away. You also need to apply the Bt every five to seven days during the window. If you’re like me and have a job and other life commitments, finding time to spray after even the smallest rainfall in addition to the weekly applications, it’s a lot. Especially when this is also prime time for weeding.
For this growing season, I tried to evade the squash vine borer altogether by waiting until after the 1100 growing degree day mark, which is the point when the moths have laid their eggs inside the vines. And I have to say, so far it’s been a success. The downside to this, though, is that my plants have just gone into the ground so it will still be a few weeks until I’m enjoying a fresh cucumber. My thought is, though, that it’s better to have some cucumbers later in the season than none.
I have a few squash varieties I still need to transfer into the ground, which I plan to do over the next few days. A bonus to waiting is that the plants were safe from a series of major storms that swept through my area earlier this week. No vine borer and no storm damage is a big win for me.
I will still watch for signs of squash vine borer over the next few weeks, especially since this was my first time using the wait to plant tactic. And maybe I won’t have a 100 percent success rate this year—gardening is all about learning through trial and error.
Something is always dying in a garden, no matter how hard you try to manage everything. If you’re a gardener, you have to accept death alongside all of your beautiful and delicious success stories.
And if you haven’t killed something yet, I recommend you get a calathea.
