How to Overcome Squash Vine Borers…Without Chemicals
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I vowed to overcome squash vine borers in my garden (without chemicals), and I did it! I successfully grew several types of squash this year, including zucchini. Here’s how…
In which I determine to overcome squash vine borers
For the last few years I’ve struggled with vine borers. I wasted so much time trying to grow squash only to watch the plants die before the fruit was ready for harvesting.
I’ve also wasted time performing surgery on plants to remove the offending borers and give the plants a chance to survive. This proved to be very time consuming in my garden, with little success.
The entire process felt so demoralizing!
All the while, I was taking notes and reading everything I could find about defeating vine borers. This year, I put all of it into practice and am happy to report that we’ve had a huge squash harvest!
Squash bugs vs squash vine borers
By the way, sometimes people ask me how to control squash bugs (pictured below, on the left) because they are “killing their plants”. My guess is that, while squash bugs can indeed damage squash plants, it’s often vine borers that do the killing.
Vine borers (pictured below, on the right) are harder to detect, and many new gardeners see the squash bugs and blame them for their plants’ demise.
If your plants are doing great and then suddenly begin to wilt and die, you can bet it’s a squash vine borer.
If you inspect the vine, usually close to the ground, you’ll discover the entrance hole. Just look for where the stem seems soft. The stem may be turning brown, and there will be yellowish sawdust-like frass coming from the entrance site.
How to handle infected plants
You can surgically remove the borers from the stem by slitting the stem, removing the worms, and then wrapping the stem in tape or heaping dirt over the surgery site. However, in my experience, this is more trouble than it’s worth.
Your best bet is to remove the vine–don’t add it to your compost! It’s important to contain the vine in something with a lid until you’re sure the worms are dead.
Do not despair, vine borers are one of the toughest garden pests to overcome. Instead, let your temporary failure fuel your efforts to triumph over them next year.
How to overcome squash vine borers
I make a goal of avoiding any and all sprays or powders. Even those considered “organic” still pose a threat to pollinators and beneficial insects. Instead, I look for permaculture-style methods to manage pests.
Here’s a video about my success in defeating the vine borers. Can’t see the video? Click here to watch.
Here are the strategies I used to overcome squash vine borers and grow a lovely squash harvest this year:
1. Started seeds indoors and waited to transplant until seedlings were big and hearty.
2. Planted early, hoping for a harvest before plants succumb to SVBs.
3. Covered with lightweight row cover until plants were quite large and flowering. This is key!!
4. Grew resistant varieties like Rampincante, Tahitian Melon Squash, Illinois, and Green Striped Cushaw.
5. Allowed plants to sprawl on the ground instead of trellising. This allows the stems to root at multiple places to produce a stronger plant and to give part of the plant a chance to survive even if SVBs attack another part. Most of my squash is planted in new hügel beds where they seem very happy and have plenty of room to spread out.
6. Increased biodiversity with interplanting.
Every one of these strategies played a key role in obtaining a harvest.
Check your zone
Depending on your hardiness zone, you may face one or two generations of SVBs in the same season. Here in zone 7A, we have two.
If you live in a cooler climate where there is only one generation of SVBs each summer, you may want to consider another important strategy: planting late. If you wait to plant until after SVBs have emerged from the ground and laid their eggs, you may escape them altogether!
I’ve never gardened farther north than zone 7A, but my understanding is that you’d want to plant in early July. This may vary according to your location, so you’ll want to check with local expert gardening friends or the master gardeners in your area. Another resource could be your local extension office.
More experienced local vegetable gardeners should be able to tell you when SVBs are a concern, and when is the deadline for planting squash.
Protecting zucchini from squash vine borers
Unfortunately, vine borers love zucchini and other summer squashes. My goal this year was not to avoid SVBs altogether, but to secure a sizeable harvest before losing my plants to them.
By employing the same strategies mentioned above, I achieved my goal. In fact, in mid-August, at the writing of this article, one of my Costata Romanesco plants is still going strong. This is my preferred variety, because it does well even when you forget to harvest and the fruits grow too large.
I believe that numbers 3, 5, and 6, contributed most to the success of this year’s zucchini.
Incidentally, I grew spaghetti squash with the zucchini and it’s also producing well.
I’m so thrilled FINALLY to have overcome squash vine borers in my garden! Do you struggle with squash vine borers? Have you tried any of these strategies?
Need ideas for using up zucchini or summer squash?
- How to Dry Zucchini Noodles
- How to Freeze Zucchini
- Chicken Tortilla Soup
- Hearty Marinara with Ground Beef & Veggies
- Seasoned Taco Meat
- Paleo Chocolate Zucchini Bread
Want More Help?
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YAY for you! I’ve struggled to grow squash forever due to SVB. My mom, on the other hand, has never had to deal with them at all! It’s funny how we all have our successes & failures!
I have also tried a few other methods you didn’t mention: wrapping aluminum foil around the stem base, piercing the stem with a needle to kill the larvae, & placing yellow bowls with soap water in garden to trap the SVB moths. I don’t think the foil worked at all. I’ve found eggs not just on the base stem but further up the stem (they lay eggs differently than squash bugs, but I pick off all eggs that I can find no matter who put them there)! I did catch some vine borer moths in the water bowl (I had read they were attracted to YELLOW specifically). Maybe that worked some, but it was not a match for the number of pests. I used a flashlight at night & shined it on the stem to “see” through it. If there was a larvae silhouette there, I pushed a needle through & stabbed it. So I think I was able to kill them inside without doing the surgical removal method & burying the stem.
One year I used a syringe to squirt Bt into the stem. That was messy & I’m not sure if it “worked.” The theory was that the inside of the stem would be “treated’ so the larvae would die once it started to eat the plant.
My best success has been to pick off eggs. That’s not easy if you have a lot of plants. It’s too easy to miss the tiny eggs. But I’m able to harvest some zucchini before the plants are killed. So I consider that a success compared to what I used to deal with! HA!