Squash Vine Borer Prevention and Treatment
One of our biggest garden losses a few years ago was our squash crops. We got hit doubly by the dreaded squash vine borer damage as well as powdery mildew. It was a one-two punch, especially to our summer squash and pumpkins.
The following year, we implemented a number of strategies to fend off these attackers. Below is a list of our squash vine borer prevention measures, what worked best, and concluding with our latest measures and results.
Squash Vine Borer Prevention
Scientifically known as Melittia cucurbitae, the dreaded squash vine borer can decimate entire rows of squash and have caused many a gardener to give up on growing squash.
If you’re feeling ready to give up, please take heart and persevere. You can prevent and eliminate this problem, but it does take some effort and an Integrated Pest Management (IPM) approach, as do most pest and disease remedies.
- FRESH BEDS: plant in new beds via:
- fresh new straw bale gardens from an organic source
- crop rotation
- start seeds indoors in later winter
- PLANT –
- in early spring with protection
- or later in season
- Pest resistant varieties of cucurbit plants
- COMPANION PLANTS
- PROTECT using frost covers for protection from frost and squash vine borers[1]https://portal.ct.gov/-/media/CAES/DOCUMENTS/Alternatives/Session4Cucurbitpdf.pdf
- CEDAR MULCH around the stems of each vine
- CHECK DAILY for signs of –
- eggs and/or actual bore holes
- yellow frothy substance called frass, seeping out of stems
- PREVENTIVE SPRAY – routinely spray with BCT (Dipel) – easiest with battery powered garden sprayer which we wrote about here
Companion Plants the Repel Squash Vine Borers or Attract SVB’s Nemesis
SVB repellent companion plants are typically those whose odor tends to repel squash vine borers, and include:
- Basil
- Beans – provide nitrogen to the soil which nourishes surrounding plants
- Calendula
- Chives
- Marigold
- Mints –
- bee balm
- catnip
- mountain mint
- peppermint
- wintergreen
- Nasturtiums
- Onion
- Parsley
- Peppermint
- Radish
- Sunflower – attractive to big eyed bugs, (Geocoris punctipes), that prey on SVB eggs and larvae
- Tansy
- Thyme
- Wormwood
See more on companion plants that repel squash bugs, as well as trap plants and predator lures.
All mints are helpful, but the strongest most pungent may help most, such as mountain mint, peppermint, chocolate mint.
Radish plants have been found to be beneficial at reducing the squash vine borer population.[2]https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1217&context=envstudtheses
I plant radishes with my squash to ward off borers. It works!
~Marianne Daczko
Squash Vine Borer Resistant Cucurbita Plants
Here’s a list of SVB resistant squash varieties.
- Acorn squash
- Butternut squash, Cucurbita moschata
- Cucumber
- Cucuzza squash, Lagenaria siceraria
- Cushaw, a large green striped, gourd shaped winter squash
- Dickinson pumpkin, Cucurbita moschata, large canning pumpkin related to butternut squash
- Melons
- Snake gourd, Trichosanthes cucumerina var. anguina
- Summer crookneck
- ‘Tatume’ (Calabacita) squash
- Tetsukabuto squash, Cucurbita maxima, (similar to acorn squash)
- White bush scallop
- Zucchetta tromboncino (trombone) squash
Squash Susceptible to Squash Vine Borer
- Pumpkin
- Summer squash
- Winter squash – Blue Hubbard is one of their favorites
- Zucchini
Consider Decoy Crops
Some gardeners use these highly pest susceptible crops as squash bug and vine borer entrapment plants. You can see more on that in our article on how to prevent squash bugs naturally.
Traps – Squash Vine Borer Traps Help
This is something that seems to be working well. If there aren’t too many vine borers in the trap, (we only have one so far), that’s probably a good sign that you don’t have many, but still keep a diligent eye out.
Signs and Symptoms of Squash Vine Borers
- WILTING PLANTS – sudden loss of vitality, mushy plant stems, deteriorating fruit
- YELLOW FLUFF on stem – trails of yellow fluff along the stem of squash plants – called “frass”, (the excrement)
- TINY HOLES in vines, especially around areas of the frass
If you see any of these signs on your squash plants, you need to take immediate action.
How to Get Rid of Squash Vine Borers
Squash Vine Borer Invader Discovered
We missed a few borer holes with our injection treatments and had to take out a badly damaged plant. We found and extracted a few of the larvae hopefully in time to save the plants they were eviscerating.
It’s easy to wonder, what did squash vine borers (SVB’s) consume before we started vegetable gardens? Maybe, we can delve into that question later. We’re still needing to deal with the immediate situation that we’ve sworn to prevent the loss of our squash and pumpkins to SVB’s.
Removing Vine Borers from the Squash Stems
We used to cut the vine borers out of the stems. We’d take a box cutter and slice all the way from the point of entry till we found the borer. Next, after dispatching the borer, we’d wrapped the length of the damaged area like dressing a wound using plastic plant tape.
The alternative was taking a stiff wire and running it into the hole in either direction in order to skewer the borer. That method saved slicing the stem, but it was hard to know if the wire had done its job.
Unfortunately, neither method was all that effective and took considerable time to deploy.
BT Dipel Spray and Injections
Now we’re injecting BT – caterpillar killing bacillus, (Bacillus thuringiensis) into any holes we find, flooding the interior of the stem.
BT (Dipel, etc.,.) is an effective—and proven safe—treatment applied externally as a spray and injected internally into the stem. We’ve applied both procedures and both helped things improve.
To get rid of squash bugs and vine borers takes daily diligence.
We have about 16 squash and pumpkin plants so spending a couple minutes on each one takes about half an hour, but it’s time well spent if it works. Once we spot the yellow fluff along the stem and locate the entry hole, we just insert the curved syringe tip and flood the inside with Dipel BT.
Spinosad
We use this as a spot treatment applied with a hand-held spray bottle. However, this works best for squash bugs than SVBs, since the latter tend to be hidden within the squash stems. But we have sprayed it into the stem openings as a part of our IPM.
While Spinosad is organic, it is toxic to bees when wet. So to avoid exposing bees, direct spray as needed in early morning or late evening before and after bees are active.
SVB Traps
We’ve included it under prevention and under treatment because it is helpful for both circumstances. See the paragraph and image above on this.
General Garden Update
In late May we see our climbers jump into action. The beans and squash begin to take hold of the various vertical systems, such as the trellis for sugar snap peas and the bamboo bean teepee trellis.
As you can see from the photos, we are big fans of “growing up”. Vertical gardening is the best solution for small space gardens, and especially if you want to grow vining crops.
Please let us know what you’re doing that’s working, and we’ll add it here.