squash borer protection

adrock430(6A)May 12, 2014

I have a pretty bad squash borer problem in my garden and is probably here to stay. I've reviewed the solutions I've seen, not interested in sprays (organic or not) or row covers, cutting them out seems really tough on the plant.

Can I inject Bt into the stem as a preventative? Does anyone do this?

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Good luck. Row covers are the best way to go, but then you have to pollinate by hand. I've also heard of people wrapping aluminum foil around the base of the stem, but if you have a lot of plants it could be a task.

    Bookmark   May 12, 2014 at 9:13PM
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I injected BT once I found the buggers. Saved my squash last year.

    Bookmark   May 12, 2014 at 9:47PM
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hnycrk, does the alum. foil work? Under the stems or wrapped?

CaraRose, did you apply just once?

Thanks! Adam

    Bookmark   May 12, 2014 at 10:16PM
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I reinjected about two weeks later, I think about three times total.

    Bookmark   May 12, 2014 at 11:51PM
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Hi Adam, I've never tried it before. I have so many squash and zucchini plants that it would take forever. But if your only growing a few plants then it might be worth a try. I think your supposed to wrap the base of the stem to keep them from boering into it.

    Bookmark   May 13, 2014 at 10:28AM
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Aluminum foil only slows down the inevitable. When the plants are young, the borers will focus on the base stem. But when the plants get bigger, they pretty much lay the eggs anywhere. So if you wrap your stem, you'll get borer up the plant.

Yes BT injections does help, but it can be tedious.

Why are you against row covers?
Here is what I did last year... I covered the young plants till the female flower opened, then I removed the covers. It takes about 3 weeks until you start noticing the effect of SVBs... by that time I had plenty of squash. BT injections will prolong that time. But problem is that even if the SVBs dont do the plants in, my plants always loose vigor after they fruit for a while. They become easy aphid targets, and then powdery mildew.

    Bookmark   May 13, 2014 at 11:25AM
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following up... so I think its better to do successive multiple plantings, with row covers this way. That way as some are winding down, others are getting ready for production.
Also once your plants are infected and starting to die. make sure you pull up all the plants and destroy them ( throw them in the trash, stick them in a trash bag.) You want to disrupt their life cycle. If you can prevent the grubs from going into the ground and pupating, then you can slow down the next round.

I sometimes wonder if somehow we could coordinate all the gardeners in a certain area to quit growing squash/pumpkins for 1 year, maybe that would help reduce the population of these things!

    Bookmark   May 13, 2014 at 11:33AM
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wertach zone 7-B SC

Here is an article from Clemson ext.:


Another more detailed from Minnesota below.

I hope it helps.

Here is a link that might be useful: Squash

    Bookmark   May 13, 2014 at 1:00PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Can I inject Bt into the stem as a preventative?

You sure can try it but from my experience it just wastes the Bt and the time and effort of doing it. Bt only works if the larvae eat it. That means the borer has to be there to eat it and it has to be injected at least close to where the larvae is. Otherwise you'd have to fill up the whole hollow stem if that were even possible just in case one might show up somewhere along it to eat before the Bt bacteria dies off.

If row covers, by far the most effective prevention since it prevents the eggs getting laid on the plants in the first place, don't appeal to you then careful monitoring of the plants during the 4 week SVB season and just a stick pin to stab it with is just as effective as pre-injections of Bt would be.


    Bookmark   May 13, 2014 at 1:26PM
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I totally agree with successive planting. When some are starting do die off you have new plantings ready to fruit. Squash/zucchini is very prolific.

    Bookmark   May 13, 2014 at 9:55PM
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in my case injecting does not work. you can inject the hollow stems until you are value in the face, but the larvae are in the solid part of the zucchini stem and will not be affected. I just plant zucchini, plant tromboncino, and plant some replacement (often lacinato kale) to transplant when the zucchini die. It so happens that they die on the week the tromboncino begins production, so nothing is lost.

    Bookmark   May 13, 2014 at 10:46PM
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I've heard about tromboncino a few times in my search on this problem, i think i have to give that a try. I'll also go with a succession crop, I'll replace after the zuccs die off.

Sounds like zuccs, then they die off, then tromboncino, and hopefully zuccs again if I plant after I take out the zuccs?

Regarding the pin sticking, I keep a good eye on them and watch out for frass. Can you just stick a pin in around the frass and you'll kill 'em?

    Bookmark   May 14, 2014 at 10:29AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Regarding the pin sticking, I keep a good eye on them and watch out for frass. Can you just stick a pin in around the frass and you'll kill 'em?

First you don't always see frass. It depends on where the borer is in the stem. If he is higher up then the frass remains contained inside the lower part of the stem. The more dependable symptom is wilting/drooping of 1 or 2 leaves compared to the others.

Second, even if you do see it he will be above it. You can usually find him with your fingers if you feel for a firmer/harder/more solid part of the stem. Then you stab the pins through the stem - in one side and out the other side - several times in that location.


    Bookmark   May 14, 2014 at 5:48PM
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I ended up with planting parthenocarpic Caveli and Perfect Pick under tulle cover. I only open it to weed and to harvest. It also helps with cucumber beetles and squash bugs.

    Bookmark   May 14, 2014 at 6:30PM
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We also got hit by squash borer and, unfortunately, it took us a good while to discover what was happening. We plan to do some Fall planting and will be reusing the "raised soil mounds" these squash were in. Is this soil tainted and will the borer eggs be lingering in the soil? We will be supplementing the mounds with additional composted soil. Perhaps there are some types of veggies we should not plant in that location. Anything else we should do to make this area safe? Please help.

    Bookmark   August 6, 2014 at 11:41AM
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Some of the squash will re root where the stem joints touch the ground I've saved several that way kill the bore and hill dirt around the next joint and keep damp for a few days

    Bookmark   August 6, 2014 at 5:17PM
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daninthedirt(Cent TX; HZ10, Sunset z30, USDA z8a)

I've had some success with moschata (yes, it is SVB "resistant", which means they just have to chew harder to get into it, but they can), by heaping leaf mulch over the vines. Let the flowers stick out. I figured that if the SVBs can't find the stems, they won't chew on them. This year it seems like it may have worked.

    Bookmark   August 6, 2014 at 5:36PM
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We have used the additional soil method mentioned by oldguy60 and daninthedirt. It seems we've managed to save a few plants, but they still look shaky. For our Fall season planting, is it safe to reuse that raised mound where the squash were? Will the borers go under ground, then attack the next plant rooted there? Is there something we can do to the soil to make sure it is safe?

    Bookmark   August 7, 2014 at 10:08AM
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alisande(Zone 4b)

Re locating the larva, I read that using a flashlight at night is best. You'll be able to see through the stem and ID the larva.

I read this after I performed the surgery on four of my winter squash plants. I cut out the grub, but didn't clean out the interior of the stem (which I later read is a good thing to do). Then I tied up the incision with nylon stocking and mounded soil over it. One badly affected plant didn't survive, but the others look pretty good.

Afterward, I wondered if there could be more larvae inside the stem. I had assumed there would be only one. Anyone know?

    Bookmark   August 10, 2014 at 10:05AM
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Glo, I got this off the web:
The squash vine borer overwinters as a mature larva
hibernating in a tough, dirt-covered, silk-lined cocoon,
usually 1 to 2 inches (but up to 6 inches) deep in the soil.
In early spring the larva
enters the pupal stage. After
two to three weeks, the
pupa breaks and exits the
cocoon. By wiggling its
abdomen, and with the aid
of the abdominal circlets of
spines, the pupa moves upward
and through the soil
surface. The pupa splits
behind the head, and after
about five minutes, the moth has dragged itself free. In
another 15 minutes, the outer surface of the moth's body
has hardened and it is ready to fly.

So I believe your plants are safe, any larvae gone under should be in a cocoon to overwinter. I would rotate where I planted my squash next year. I covered mine with row covers and hand pollinated for the beginning of summer. They did get me after removing them, but I caught all of them before significant damage.

    Bookmark   August 10, 2014 at 10:47AM
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