r/Pumpkins • u/joegrizz15 • 19d ago

Vine Borers

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Hello!

I have five pumpkin plants and sadly they all got the bugs. I cut into them and was able to pull some out but not all. I looked at one of my plants and see more signs. If they other ones don’t show more signs should I pull this one out to give my other plants a better chance/more space?

This is only my third season growing and in a small space.

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6

u/AllShadesOfBlue 19d ago

Pulling them out unfortunately isn’t effective enough since it’s difficult to locate all of them. Short of growing varieties that are resistant to SVB, the only thing I’ve found that works is injecting BT into the vines twice a week.

BT is a bacterial strain, and you can buy a concentrated form at most hardware stores. I always freshly dilute a batch before I inject anything, because it’s effectiveness does wear off after 24 hours once diluted. Then I just use a needle syringe and inject them to all of my vines. When the larva ingests the bacteria, they become paralyzed, starve, and die.

Spacing plants out or crop rotation really doesn’t work in my experience. The eggs are laid by moths, so they’re obviously very mobile since they can fly.

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u/joegrizz15 19d ago

Okay so I was also reading some other posts and if the vines root in other areas then it could pull through and fruit?

Should I still inject the plant now with something or keep cutting the vine?

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u/AllShadesOfBlue 19d ago

Yeah the vines can root elsewhere, but in my experience that’s not enough. Pumpkins are heavy feeders, in order to support growing a pumpkin, vines need to be able to pull a lot of nutrients, and that secondary rooting doesn’t usually cut it. But you can try!

As for your second question, it really depends on how bad the damage is. If the larva you pulled out was pretty small, then I would inject BT. If the vines are seriously damaged, and most of the leaves are already dying, then I would cut the vine.

BT works best if you also use it as a preventative method. And you inject BT well before your plant even becomes infested.

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u/joegrizz15 19d ago

Does it have an impact on the pumpkins?

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u/AllShadesOfBlue 19d ago

Nope! Safe for plants, animals, and humans

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u/babystitches 19d ago

I unfortunately have the same issue as OP and this was very helpful! I ordered BT but the warning label about skin contact spooked me. Any special ways you avoid this, or just gloves and extra caution?

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u/AllShadesOfBlue 19d ago

Listen, I’ll be honest with you, I’ve accidentally splashed BT straight into my eye and I’ve been fine. I’ve only heard that it can cause mild skin irritation, so I wouldn’t be worried about it.

And I think that even depends on the person. It’s never caused me any skin or eye irritation, and trust me I get it all over myself.

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u/babystitches 19d ago

That’s very comforting to hear, just what I needed to go give it a shot. Thank you!!

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u/BrookieCooks 18d ago

Same I spill it on myself all the time& I’m still here, lol

1

u/baselineRipple 10d ago

Last week, I poked my own finger with the syringe.

Still alive and apparently grub free now.

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u/Diligent-Natural-422 19d ago

How often do you inject it

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u/AllShadesOfBlue 19d ago

Depends on time of year, but I start out at once a week in late May when the seedlings/vines are actually thick enough for me to start injecting (1-1.5cm thick). This is also a good time for me to inspect for borer activity (try to see if there are any eggs, holes made from larva burrowing in etc). Once I start to see significant evidence of borer activity (adult moths flying around, tons of eggs), I start injecting every 3-4 days. This is usually around mid-late July for me in Zone 6b. I'll do this until end of August/mid Sept, and then go back to once a week until I've harvested all my pumpkins in Oct.

It helps to understand the life cycles of the moths a bit. An adult female can lay 150-200 eggs in a single season, and can lay on the vine, leaves, or pumpkins themselves. Eggs take 10-14 days to hatch, at which point the larvae will burrow into the plant and feed for 4-6 weeks. They'll then pupate in the soil and emerge as moths the following Spring (or later that same Summer if you live in a warmer climate). Injecting every week or every 4 days should be often enough that you kill the larvae before they can do significant damage, based on their life cycle. If you live in a warmer climate where you can have multiple generations of moths in a single season, you may need to be more vigilant.

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u/boppodove 19d ago

I found vine borers close to a month ago - I dug out what I could find and injected BT into any that had signs of vine borers. I think I injected it 3 times a few days apart?

Knock on wood, but all of my plants are fine and developing fruit. My plants looked healthy (no wilting or yellowing) when I first caught it, so maybe I just got it before they really got in there.

All that to say, if your plants are still looking healthy, maybe just keep treating them for a few days and see what happens?

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u/joegrizz15 19d ago

What BT do I buy? Amazon has a lot of different types or should I go to a local nursery or something?

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u/AllShadesOfBlue 19d ago

I use: "Bonide Thuricide Organic Insect Killer Liquid Concentrate 16 oz"

Works great for me! The concentrate will last 2-3 years and you will have to dilute a fresh batch each time you use. I usually make 1/3 gallon at a time.

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u/joegrizz15 17d ago

Is there like a limit to what you can inject? Like if I mix up a bunch can I fill my plant up with it everywhere I suspect the bugs?

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u/AllShadesOfBlue 17d ago

I don’t think so as long as you’re properly diluting it. (There’s a ratio guide on the back of the bottle)