July 22, 2012

Invasion from Within: The Squash Borers Attack "Alien" style

My exploding foamy squash vine
Squash Borers.  I hate them.  I've only just met them, and I already hate them.

Yesterday, I went to weed around the squash and saw that the vines near the soil looked like something out of a science fiction movie.  The insides had turned into foam and burst from the confines of the vine walls.  It was creepy, and I wondered what bacteria could do that.  They were beautiful, and everything was growing well one day, and the next, it was like they'd dissolved into creepy foam.

I googled "squash vine foam" and discovered pictures that looked exactly like my squash:  I had vine borers.  According to the University of Minnesota's extension website page on Managing Vine Borers in Home Gardens, all of this destruction was caused by the nasty larvae of a kind of a funky looking clearwing moth.  I knew nothing about this thing, so all the information below is from them.  You should check out their full article for a more detailed explanation, and read more for my short one.

ABOUT VINE BORERS (the little basta'ds)

The moth, which looks like an orangeish red wasp and flies during the day (seriously) is 1/2 inch long and dotted with black.  They come out of the ground in June/early July and fly around looking for their favorite plants (pumpkin, winter and summer squashes) and lay one tiny (1/25") flat brown egg at the base your vines.  The eggs hatch into a whitish 1" long larvae--I'd have found you one, but I was too angry yesterday to be all calm and scientificy about it.

The nasty beasties then burrow into your fine and eat it from the inside, turning the vine into a straw basically, and secreting the nasty foam explosion--which is called "frass," by the way.  I have to admit that I had to pause at the coolness of the word and learning something new even in the midst of the dawning realization that these little dudes were pulling an Alien chest burst in slo-mo on my plants.

In the process of gnawing their way through your hard growing plants, they cut of the water supply to your plant, wilting the leaves.  After about a month to a month and a half, you know, enough time to completely destroy your crop, they leave the dying plant and dig into the ground about an inch or so and hang out until the following summer, when they emerge in their orangy wasp-looking glory and destroy your next crop.


wilting leaf from a week ago
A week or so ago, I noticed the squash and pumpkins had a few leaves that were yellowing and wilting.  I assumed not enough water for such explosive growth, and watered them.  The problem didn't seem to spread, but the leaves didn't get better, so I didn't worry.  Hindsight being what it is, I should've worried since wilting leaves is one of the first signs of vine borers.

I looked everywhere to figure out what to do, and it turns out there isn't much once the larvae is in there gnawing.  You can try to remove the larvae from your vine, by using a knife to carefully slice up the vine starting from the explody-foamy part (or the hole if it hasn't exploded yet).  Eventually, you'll find the larvae, and you can remove it and kill it with the already handy knife.  If the damage isn't too bad, your plant might survive.

However, several of the little buggers can attack a single plant, so if you find one, you may not have stopped the problem.  You'll need to keep looking carefully at the vine to find others.  Once you're satisfied you've killed them, bury the vine in the soil (easiest just to lay it down on existing soil and mound up soil around it) and perhaps it will grow roots.  But, every website I went to said this was highly unlikely to help.  Think zero to 1% success rate, and then even if it's early on.  BUT, if you love your plant, or have a short growing season, you may as well give it a try.

my squash in the trash can
My mom (a great gardener) had a much more drastic solution.  "rip them up, and throw them away" she said calmly when I called her.
"No!" I protested.  "I worked hard on these."
"Give me a break," she replied nonplussed.  "They're squash, it's harder to PREVENT them from growing.  You've got to rip them up or you'll lose all your vines.

I grumbled at my mom's practicality, but the University backed her completely, saying "Promptly pull and destroy any plants killed by squash vine borers,"  and I had to admit that exploded vines were a probable sign of imminent plant death (much like the exploding chests of any minor character in an Alien movie) no matter how pretty the pumpkin on the end of it was.

So, I pulled up the darn vines and threw the bastards away.  It was not a happy moment, and my garden looked naked where the lush vines once were.  I was tempted to try the 1% success solution with my pumpkin by cutting off the vine well above where the squash borer was and mounding it, but I just can't see a rootless vine producing enough nutrients to nurture a fledgling pumpkin.

So, what now?  Well, the University extension calmly points out that Vine Borers only appear once a year, so if you plant a late crop after the larvae have emerged and died, you can avoid them altogether. I looked despairingly at my now nearly naked garden corner, and thought about their exact words "A second planting of summer squash made in early July will mature after adult borers have finished laying eggs."  I'm sure I have some seeds somewhere, and if not, I'm sure I can get them.  It can't hurt, and it's not like they're going to rise up and attack again.


It turns out prevention really is the only effective way to deal with these things.  Here are more recommendations from the awesome people at University of Minnesota.  Again, their page has detailed explanations for each of these, so I'm putting a link to it after each paragraph where they give more detail.

Plant Right

The moths don't like all vine crops.  They aren't fans of butternut squash or cucumbers, and they actively dislike melons.  So, if you plant those and your neighbor plants pumpkins, then the moths will fly over there to lay eggs.


Starting in late June, pay extra close attention to the base of your squash vines.  The moths are distinctive--I did mention they were ORANGE and looked like wasps, right?--it turns out they also buzz loudly.  So be on the lookout for the suckers flying around in your garden.
Lay out yellow traps for the little suckers.  They're attracted to yellow, so if you take a yellow bowl or bucket (check out the Dollar Store) filled with water, they'll fly in and drown.  They recommend checking traps at least once a day, and I recommend stirring the water a bit so they don't also become mosquito breeding grounds.  If you see even a single moth in your traps, you need to go on to the next step (personally, I'm all for just doing the next step anyway, but then I may be biased right now).

Block 'em

Place floating row covers over the rows of squash starting either when you see the first one in your trap or in late June and leave them on in for 2 weeks.  You'll want to anchor the row covers so that they can't get underneath.  The only problem with this is that bees won't be able to pollinate your flowers, so it only works if you hand pollinate or if your plants are already pollinated or if you're cool with them not pollinating for a while.

Kill 'em
Yep, you can totally use insecticides on these suckers.  Basically, you'll spray or dust the base of the stem either when you see the first beastie in your trap or when the vines start taking over in earnest (you know, late June/early July).  Then keep it up every week to 10 days until the end of July to nail any of the larvae that managed to survive the first dusting or two.
The UofM website has specific names of good insecticides to use, and of course keep in mind your gardening style and whether or not children or animals will be in contact with the squash when deciding on insecticides.


So that's it.  My garden is nekkid.  The triumphal spread of squash has halted, and I'm ransacking the neighborhood looking for squash seeds to plant for fall. I'm tempted to go drag my beautiful pumpkin out of the trash and try getting roots to grow, but at the same time, I know it's just lengthening the already traumatic good bye process.

On the plus side, now I can grow the pumpkin on the trellis from the start.  I think I'm grasping at straws here, but still. . .there's that.

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