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How to Control Squash Vine Borers Organically

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Don’t let squash vine borers get you down! Here are a few tips for preventing and controlling this destructive garden pest using organic methods…

The squash vine borer is a dreadful garden pest that can destroy your entire squash crop if you happen to live in an area where this pest is prevalent. (It has happened to me more than once, although I was not even aware of this insect before moving to Ohio…)

The squash vine borer is common in the eastern United States and typically feeds on both summer squash and winter squash varieties, although some varieties are more resistant to this pest than others. The borers overwinter in the soil in large, brown cocoons, emerging as large black and orange moths in the spring, when they lay eggs near the base of squash stems. Once the eggs hatch, the larvae bore into the stems and feed for several weeks, causing wilting of the plant’s leaves, rotting stems around the base of the plants, and often, death.

Here’s a picture of my squash, dying from vine borers a couple of years ago, plus one of their cocoons that I found while digging in the garden last summer:

Squash vine borer damage
Squash plants dying of vine borer damage.
Squash vine borer cocoon
A cocoon of the squash vine borer moth larvae.

That said, there are a number of ways to control the squash vine borer and save your plants. However, the best method of control is always prevention. (Now that I am armed with this information, hopefully, next season’s squash crop will fare better than the last one!)

Below are a few tips for both prevention and control of this pesky garden menace:

Prevent Squash Vine Borers

  • Sometimes the best solution is to start your squash as early as possible. This way you’ll be harvesting before the summer time when vine borers become active – at least for summer squash. If you plant early, you may need to be prepared to cover your plants in case of frost.
  • Do not plant squash in the same bed two years in a row. Squash vine borers overwinter in cocoons in the soil. Also, clean up ALL debris and clean up your soil in the fall.
  • As soon as the squash is harvested, get rid of the vines. Till the soil in the fall and spring to get rid of overwintering pupae.
  • Preventative measures include covering the stems with a barrier, such as strips of nylon stockings or aluminum foil, to prevent egg laying.
  • Sprinkle diatomaceous earth around the stalks when the squash vines are small. Reapply after rain. Also, build up the soil around the vines. Or, sprinkle black pepper around the plants as a defense.
  • Adding parasitic wasps to your garden prior to the egg stage can be helpful as these wasps are the borers’ natural enemy.
  • One of the better solutions is to cover crops with floating row covers to prevent egg laying (but only if you are sure there aren’t pupae overwintering in the soil). You can also drape these row covers over frames. This will not only give you a head start over pests but protect your plants from strong heat and frost.

If despite all your efforts at prevention, you still notice signs of this pest affecting your squash, here are a few organic control tips:

How to Get Rid of Squash Vine Borers

  • If you catch them VERY early, you can manually remove the squash vine borer. Slit the lower stem lengthwise with a fine, sharp knife to remove the grub-like larva by hand. One plant can house several larvae. After removal, cover the slit stem section with moist soil above the point of injury to promote formation of secondary roots. Also, extra rich soil near the vines helps rerooting.
  • Or, if you spot entrance holes and “sawdust,” try inserting a wire and thread through the stem for some distance to kill the inside larvae.
  • If possible, catch and destroy the moths at twilight or in early morning when they are resting on the upper side of leaf bases.
  • …The bacteria Bacillus thuringiensis v. kustaki (Bt) is a natural insecticide that can be injected into and applied to the squash stems, however, it is not always effective because the larvae are protected inside the plant.
  • >Trap the adult orange moths with yellow sticky traps and yellow-colored bowls of soapy water…
  • An old folk remedy from The 1963 Old Farmer’s Almanac says that wood ashes were effective against the squash vine borer.
Read more at Almanac.com

 

Image Credit: Featured image by Abby Seaman, NYS IPM Program. (CC BY-SA 2.0)

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