Squash Vine Borers and BT

[A.Lyric]

I quit planting summer squash, having admitted defeat in my battle with squash vine borers. I had done everything I could think of, including plant surgery. Then I read something about injecting squash vines with BT to prevent/kill the borers and watched a number of YouTube how-to videos. I decided to give it a try so planted squash again this year. This time I planted in containers with fresh Mel's mix to avoid anything that might be lurking in my garden soil.

I got the BT, got the needles, waited until my squash had some growth and had started blossoming, and injected the BT per directions. A couple days later I noticed that the areas I injected with BT, on an otherwise green and healthy looking stem, had sunken in on itself and turned a gray color. Then the leaf itself went limp. I had to cut off those leaves. The plant is healthy and seems to be thriving in spite of losing those leaves, but I've never heard of this happening. I tried to google it and got nowhere.

I was so hopeful. Now I'm scared to use the BT again! Does anyone have positive/negative experience injecting BT on straightneck summer squash?

 

[Toddz]

I wouldn't be scared to use BT again but I definitely wouldn't recommend injecting it. Rather apply it like the bottle suggests.

 

[A.Lyric]

I wouldn't be scared to use BT again but I definitely wouldn't recommend injecting it. Rather apply it like the bottle suggests.

Yes, I'm not afraid to use it per directions elsewhere in the garden if needed, I'm just wary of killing more squash stems with it. There are no directions on the bottle for injecting it into squash vines, but based on the many experiences/successes shared by others online, I'm convinced I must have done something wrong and injecting likely works if done properly.

I might try one more time with a weaker solution on a single stem and wait a couple days to see the effect. I should have tested it on just one stem in the first place. Fortunately, in spite of the dismal result of my enthusiastic injecting, the BT didn't kill the plants like the vine borers faithfully have and the plants have coped pretty well with the loss of leaves.

ine borers are my gardening nemesis. And eventho' my battle so far has not turned out well, I'd rather tweak a bit than give up. Hopefully, I'll learn something and, if so, I'll share it. Thank you for your response!

 

[Chuck]

Yes, I'm not afraid to use it per directions elsewhere in the garden if needed, I'm just wary of killing more squash stems with it. There are no directions on the bottle for injecting it into squash vines, but based on the many experiences/successes shared by others online, I'm convinced I must have done something wrong and injecting likely works if done properly.

I might try one more time with a weaker solution on a single stem and wait a couple days to see the effect. I should have tested it on just one stem in the first place. Fortunately, in spite of the dismal result of my enthusiastic injecting, the BT didn't kill the plants like the vine borers faithfully have and the plants have coped pretty well with the loss of leaves.

ine borers are my gardening nemesis. And eventho' my battle so far has not turned out well, I'd rather tweak a bit than give up. Hopefully, I'll learn something and, if so, I'll share it. Thank you for your response!

Injection works. Where most folks fail in the attempt is they do not inject in more than one spot. Where ever you see the frass inject about 12 inches above and below where you see it and don't use it sparingly. Injecting a squash stem is just like a person getting a shot at the doctors office. It does not hurt the stem as it only makes a small hole, very unlike the hole the worm makes. Bt is mixed at 1 1/2 ounces per gallon of water or 3/8 oz per quart. I use 1/8 oz per half pint of water when injecting. The liquid will flow through just about any needle but I use the largest needle I can get from the animal vet.

 

[A.Lyric]

Injection works. Where most folks fail in the attempt is they do not inject in more than one spot. Where ever you see the frass inject about 12 inches above and below where you see it and don't use it sparingly. Injecting a squash stem is just like a person getting a shot at the doctors office. It does not hurt the stem as it only makes a small hole, very unlike the hole the worm makes. Bt is mixed at 1 1/2 ounces per gallon of water or 3/8 oz per quart. I use 1/8 oz per half pint of water when injecting. The liquid will flow through just about any needle but I use the largest needle I can get from the animal vet.

 

[A.Lyric]

Omgoodness! You don't know how encouraging your response is!

I was injecting straight BT with no water! About two inches of the stem where I made the injections turned gray and wilted and sort of collapsed. I planned to inject them every seven days as a preventative measure, but that confused and scared me.

I'm going to do it your way, dilute it, do a single injection on a single stem and see how it reacts. I was just was in “overkill” mode with the BT.

Thank you so so much!!

 

[Chuck]

Omgoodness! You don't know how encouraging your response is!

I was injecting straight BT with no water! About two inches of the stem where I made the injections turned gray and wilted and sort of collapsed. I planned to inject them every seven days as a preventative measure, but that confused and scared me.

I'm going to do it your way, dilute it, do a single injection on a single stem and see how it reacts. I was just was in “overkill” mode with the BT.

Thank you so so much!!

NO, not a single injection. If you see frass inject about 12 inches above AND below where you see it. If you do not see frass, start injecting about 2 1/2 feet from where the stem comes out of the ground and work backwards injecting about every 6 inches.

 

[Chuck]

Oh, I forgot. If you make about a pint of Bt solution add about 1/4 teaspoon of molasses. This will enable the Bt to be active a lot longer.

 

[A.Lyric]

NO, not a single injection. If you see frass inject about 12 inches above AND below where you see it. If you do not see frass, start injecting about 2 1/2 feet from where the stem comes out of the ground and work backwards injecting about every 6 inch

 

[A.Lyric]

I'm going to inject ONE stem. And if that stem doesn't die like they did before when I was in overkill, I'm going to chisel your BT advice on a stone tablet. Well, except for the molasses.

I got BT this spring solely for the purpose of killing squash vine borers and/or preventing them from destroying my squash yet again. It was my last hope.

Reading your response convinced me I had just been too ignorant and careless and enthusiastic with the BT, and I should try it again. So that's my plan. And if that one stem I try it out on does not turn gray, wrinkled, sunken, and die, you will be my squash hero.

In the meantime, I still have a bit of BT paranoia, so will proceed with caution.