Operation Squish: Axis of Evil

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Zucchini in Fenceline GardenIt’s a good thing that my title is “Gardener” and not “Scientist” because I’ve thoroughly botched the squash bug experiments I promised you. To recap my original post regarding Operation Squish, I intended to do the following to ward off an attack from my nemeses, the pesky squash bugs:

  1. Skip mulch in zucchini/squash beds.
  2. Use a row cover for zucchini/squash beds.
  3. Use a neem oil recipe as an organic pesticide.
  4. Remove squash bug eggs.

These enemies are not alone in their plight to destroy our squash. Another pest – the Squash Vine Borer – has joined them and created a Squash Pest Axis of Evil. Here’s an update on the ‘experiment’ thus far and on the effects of the Axis in our garden.

Mulch

I’m pleased to report that I’ve come through on this one! We skipped mulch in the squash beds because squash bugs like to develop and hide beneath it. When they’ve appeared, this step has made it much easier to spot them and I recommend it.

Row Cover

Row CoverWhen I first transplanted my squash into the main garden, I used a row cover of greenhouse plastic. This was in May when we were experiencing record-setting heat. Using an indoor/outdoor thermometer, I discovered that temperatures in the bed were reaching a scorching 120+ degrees and quickly had to abandon this idea. Though the plants continued to be green and to blossom, their yield was significantly hindered later in the season (June and July) and I think this high heat exposure – along with similar drought conditions outside the cover – was a significant factor in their production problems. Next year I’ll try using light-weight fabric row covers instead. These row covers are typically made of polyester. They allow rain and some sunlight through but protect plants against wind, fungal diseases and (drum roll) pests, while still allowing airflow to keep plants from overheating. The fabric is light weight enough that you can simply drape it over the plants and they will push it up as they grow. However, a tighter seal is more likely to keep pests (birds, insects, etc.) out, so I plan to attach to the existing PVC pipe hoops bent over each of our beds. The only drawback? Pests are kept at bay, but beneficial insects like bees and butterflies need access when the covered plants require pollination. This means I’ll need to come up with a plan for opening the covers at certain times to allow the good guys to come in. Not a fool-proof plan, but it’s better than nothing.

So that’s the long way of explaining that I abandoned my row cover after only a week or two of use. I did, however, keep a keen eye out for squash bugs and their eggs. Well… at least until I got really busy…

Use Neem Oil

Big. Fat. Fail. I never got around to purchasing the oil needed for this organic pesticide recipe. I’ve planted a few late-season squash plants (golden zucchini and patty pan squash), so hopefully I’ll have my act together enough to try this technique on them.

Remove Eggs

Squash Bug Eggs on Underside of Leaf

Squash Bug Eggs

I can’t say that I’ve been as diligent as I could have been, but I have set aside time on several occasions to go Squash Bug hunting – for adults and eggs. Finding them is kind of like the antithesis of discovering a $10 bill in last season’s purse. If you had observed me during these events, you’d hear intermittent and uncontrolled gasps each time I found one. After crouching over and staring for several minutes, suddenly laying eyes on an adult squash bug feels kind of like sensing that you’re not alone in your bedroom at night and then looking up to find that you’re correct. (Even if it is only the dog…). Next, I feel like they’re trespassing (invaders!). And all of this justifies what happens next – a speedy and fervent SQUISH! (With gloves, mind you. I’m not that earthy… yet.) Last week when I made my squash bug hunting rounds I found several adult bugs, but I was appalled at how many eggs I found!

I happened to be removing dying plants in this particular bed (which was severely impacted by the drought) so I had a large bucket full of plants and leaves with squash bug eggs. What to do with them? I didn’t want to compost them because I was afraid the eggs would survive and be living in the compost I’m going to add to all my beds this fall. I dislike these pests so much that… well… I decided to burn them. Leaves, bugs and all.

I spent about 20 minutes starting a decent campfire (in a metal pit, mind you) only to discover that green squash plants don’t really burn. Instead they do this smothering melting thing. However, due to the recent rain, I had a wheelbarrow half full of water and I decided to drown them instead. So I tossed all the plants, eggs and adult bugs into the water. It’s been a while (nearly a week). Pretty sure the bugs are dead, the eggs are ruined, and now my swampy mixture is going right onto the compost pile.

Sometime this weekend I’ll be hunting for more squash bugs as I have squash in several parts of the garden and have seen eggs elsewhere.

Vine Borers: An Evil Alliance

Though my squash bug population is somewhat in check, I’m sorry to announce that I’m having an issue with other invaders: Vine Borers.

According to Wikipedia:

“The squash vine borer (Melittia cucurbitae) is a diurnal species of sesiid moth that attacks wild and cultivated varieties of squash. The moth is often mistaken for a bee or wasp because of its movements, and the bright orange hindleg scales. The females typically lay their eggs at the base of leaf stalks, and the caterpillars develop and feed inside the stalk, eventually killing the leaf. They soon migrate to the main stem, and with enough feeding damage to the stem, the entire plant may die.”

Squash Vine Borer

Last year I had major issues with the caterpillars but knew nothing about the adults. My beautiful zucchini plants were huge and green and then suddenly started turning yellow and wilting. After some research, I discovered that vine borers were to blame. This year, I noticed the adults much much earlier than squash bugs – but thought it was some type of wasp and let it live! Now that I know what they look like, I won’t make that mistake again. If your otherwise healthy squash plants begin to turn yellow and wilt, vine borers may be to blame. Keep an eye on vines and stems to find signs of sawdust-like frass coming from little holes to detect the caterpillars (larva) inside.

To address the problem, I identified the area of the stalk where most of the damage had been done. (If possible, I removed the vine borer.) Then I piled dirt and compost onto the damaged area and watered like crazy. (When you think you’ve watered way too much, keep going for 20 more minutes.) The additional dirt encourages nodes along the stem to take root, providing an additional root system to the damaged plant.

Using this method, I was able to save my zucchini for the remainder of the season. (They were still producing when I pulled them out in September to experiment with other plants.) Since I’ve seen vine borer damage in almost all my zucchini beds this year, I’m hoping the method will work just as well for 2012. Here are some other approaches I discovered:

  • Aluminum foil or nylon stockings wrapped a couple of inches from where the stem comes out of the soil in order to prevent egg laying
  • Use of row covers
  • Carefully cut the larva out of the stem (cut vertically)
  • Use an unfolded paperclip or other sharp object to kill the larva inside the stem before it does much damage
  • Keep the garden clear of dead vines or rotting plants as keeping these around will allow the larva to completely develop

And next year, I’ll add those orange-ish vermin to my Most Wanted list!

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