Friday, June 8, 2012

Archenemy #1: Squash Vine Borer

There are few things I truly hate, but vine borers make it to the top of my list.  If you have never met a vine borer as a gardener, count yourself lucky.  They are a species of moth that lay their eggs on the stem of squash plants.  The caterpillars then eat into the stem of the squash and cut off the transport and nutrients and water from the roots to the leaves.  The squash start to wilt and the entire plant dies.  Plus, in the south we have a long enough season to get two rounds of vine borers.

This year I had a battle plan for the vine borers.

Step 1:  Plant resistant squash varieties.  C. moschata varieties are suppose to be more resistant to the borers.  I planted tromboncino squash which can be picked young and can be used as a summer squash.  I also planted Sweet Mama Hybrid squash which is a acorn squash that is *suppose* to be resistant.

Step 2: Plant a trap crop.  Hubbard squash are suppose to be one of their favorite varieties, so my plan was to plant them as a trap crop and kill the evil borers!

My battle plan is not going as expected!  My sweet mama squash started wilting (remember that this one is suppose to be resistant).  Checking out the stem, this is a red flag that there's a vine borer inside:

Sometimes you can cut out the vine borer and bury the damaged part of the stem and the plant will survive.  I tried this and here you can see my archenemy:

Don't be fooled by its small and harmless appearance- these guys are evil! 

I buried the stem and hoped for the best.  Unfortunately the plant wilted and died.  I pulled it up and found that there was a second vine borer!


7 of the 9 Mama Hybrid Squash have died
1 of 3 Hubbard Squash have died
0 of 6 Tromboncino Squash have died

The trap crop is doing better than one supposedly resistant variety, but so far tromboncino is the survivor.  All three hubbard squash have been attacked, two have survived so far.  I cut one borer out of the one that died.  As the plant continued to die, I pulled it and opened it up.  There were four more vine borers!  I've never seen that many before and this was at the end of May!

And the battle goes on...

 Any suggestions on how to win the battle or even how to survive the battle with a few squash plants alive?


  1. For winter squash I only grow the C. moschata, though I do have a hybrid one that is supposed to be resistant. I'll find out this year if it works or not. Because here I've had every single plant taken down if it isn't a C. moschata. But I do love my butternuts. Though for the zucchini I'm going to try to row cover them for the first time. The borers here only have one hatching and it lasts a few weeks. So those weeks the squash will be covered. At least that is my hope. I just have to time it right. Supposedly they come out at around 1000 degree days. So I'll probably cover them before that.

    1. I just planted some butternut seeds to replace the supposedly resistant squash. I hope they'll have enough time to grow! I've contemplated row covers before, another battle plan option. I need to pay more attention to when the adults are around laying eggs, so I know when to cover them. I didn't know that about degree days that could be really useful. I've even thought about covering them all season long, but that would require hand pollination and I'm too lazy for that!

  2. Here are a couple ideas. You may have already tried them, but if not, they may help in the future.

    Cut little pieces of row cover and use them to just wrap the vine. Do this before you plant, so that the covered section of the vine extends below the soil line; and add more wrapping as the vine grows larger.
    The most reliable cure may be to grow your squash out in the open and use vigilance to get the eggs. You may not be able to see them, but a weekly spray of the vine with insecticidal soap will smother them nonetheless (use a commercial product, not home-made; there is a fine line between beneficial soap and plant-killing herbicide).
    Or use BTK. It is organic and non-toxic; one of the oldest organic pest controls. It’s sold under brand names like Dipel, Thuricide and greenstep, It kills caterpillars that munch on the sprayed plant part; it affects nothing else. So spray the vines once a week and there will be BTK on the stem when that hungry, hungry caterpillar comes out and starts munching.

    One last tip is that they egg clusters can hibernate over the winter, so either move the plants to a new spot every year or else turn the soil well dealing death and destruction to all that you find. Nematodes are supposed to help, but I’ve no experience. I bet a local nursery or master gardener would be able to advise you best, but these are my ideas. Hope they help!

    1. Thanks for all the suggestions! I tried wrapping the vines with pantyhose last year and they still got in there. I probably didn't secure them on there tight enough. I haven't tried sprays.. yet. I need to be more diligent about looking for eggs, but I've never noticed them. BTK sounds like a good option.. battle plan for next year!

  3. Ugh! I hate those little buggers! I have a battle plan this year too which includes wrapping the vines and spraying the vines like ignorant gardener mentioned. I also was told that once the borer is in the vine you can inject the vine with beneficial nematodes. This supposed to kill the borer without harming the plant.

    1. I tried wrapping the vines last year and it didn't work for me. I haven't tried spraying or nematodes yet.. good to know there's other battle plan options.

  4. I am very very glad we don't get this particular brand of evil here.

  5. I feel your pain! All of winter squash fell to the pest, I was hoping the summer crop would fare better. No luck :(

  6. I've been battling them this year, on my pumpkins, acorn squash, and yellow squash.
    Here's what I have done, and so far so good:
    1. check for eggs... they can be everywhere! Small reddish brown disk shaped eggs laid singly, mostly on the vine, or leaf stems, or where the stem meets the leaf. I've picked off hundreds so far this season. If I hadn't noticed them my plants would be toast by now. (my earlier crop of Yellow squash suffered this fate, before I educated myself).
    2. Undoubtedly I have missed some eggs. So what I do is check the vines and leaf stems for frass (mushy yellow stuff coming out), or a yellowing instead of green color. Then I have injected with BT, where I have seen this. If I find a lot of frass, I have also washed out the area, stuck an electrical wire, and harpooned the bugger! Has worked well. Then I inject with more BT just in case I missed one. So far I have done this about 5 times, and the vine have been recovering.
    3. Covering the base of the plant with lots of dirt (once I make sure no eggs are there). Covering the vines with dirt also. I've tried to make sure my vines are on the ground, and covered them when possible because it helps the plant send more root down from the vine, and that makes the plant stronger and more resistant to attacks. On my Acorn squash, which suffered earlier damage, this has helped them a lot.
    4. Next year I plan to cover my plants with Tulle netting, until the female flowers appear. Then afterwards hopefully, vigilance and vine covering can help the plant survive until I get a good harvest.