- Author: Harold McDonald
A gardener struggling to use mountains of zucchini is almost a meme in the gardening community, so it's very humbling to have to tell people you can't grow it—kinda makes you look like a grade down from a Master Gardener! And even though I know my conditions are extreme out here at the edge of the Volcanic Tableland, my pests normally come on four legs, not six. So, having to surrender growing squash to the bugs that stole their name is pretty frustrating. But I know this is a situation that many better gardeners than I have surrendered to!
The normally-more-than-daily examinations of each giant, sticky, rippy leaf for the glistening little bronze eggs, all while the progenitors scurry for safety in the folds of the struggling squash plant is just more than most of us are up for.
I know people have lots of strategies to deal with these pernicious pests, but none that have ever seemed worth the work to me. All require diligence. Leaving home for even a few days can throw momentum back to the bugs. More than that and the situation could get completely out of control!
But gardeners are always dreamers, and long before the days warm up in the spring, we are scheming, trying to solve seemingly unsolvable problems—at least I am—and squash bugs is a tough one. I started searching online, but again, the solutions weren't easy, realistic, or convincing.
Somehow, while researching squash I stumbled on parthenocarpy, a term I had learned somewhere back in a plant class, but certainly not a term I would have known to search for. Seedless watermelons are parthenocarpic—production of the fruit does not require fertilization of the ovule. For more about parthenocarpy and cucurbit sex, see this University of Nebraska pdf.here.
The important thing is that since fertilization is not required, you can keep the plants under floating row covers for their entire lives, physically protecting them from squash bugs. If you're inexperienced with row covers, they can really help in a number of situations, probably more commonly to raise temperatures in the shoulder seasons. Here's an introductory article on row covers from a MG blog in Wisconsin.
Yeah, but where do I find seeds? If they're parthenocarpic, do they even have seeds? Yes, they do have seeds, and some of the top varieties are ‘Cavilli,' ‘Venus,‘ and ‘Gold Rush.' I chose ‘Partenon'*—who can resist a squash that seems to have been named after a Greek temple? I planted the seeds in the ground in late May without a clear plan of exactly how I would cover the plants. But they did indeed come up. I improvised something from bits and pieces I had laying around, and eventually built a more robust but very simple portable hoop house (rebar and PVC) for them.
The results have been beyond what I could have imagined. So far, no squash bugs and plenty of zucchini! I'll do this again next year in a different part of the garden. I may look for an additional parthenocarpic variety. This field test from Cornell ranks ‘Dunja' as even more efficient than ‘Partenon.'
But with success, I'm now the one searching my cookbooks, Paprika (an excellent recipe database program for your digital devices) and online for good ways to use the bounty. Today I made zucchini pickles and a fabulous zucchini butter that will go great on crackers or bread, perhaps with a bit of pesto or fresh basil on top and—with any luck—tomatoes later in the season!
*By the way, in the University of Nebraska presentation, they refer to ‘Parthenon' zucchini from Thompson and Morgan. It is actually ‘Partenon'—no h in there!
Resources
https://agronomy.unl.edu/documents/parthenocarpic_zucchini2008.pdf
http://www.hort.cornell.edu/expo/proceedings/2014/Vine%20crops/Seedless%20squash%20Reiners.pdf
We have all fought the squash bug and lost the battle. This bug is the most serious enemy of our growing successful squash and pumpkin in the USA. The squash bug is only found from Canada to South America. Both adults and nymphs damage plants by sucking juices out of the leaves. The leaves then lose nutrients and water, become speckled, then yellow, then brown, and finally, the plant totally wilts. The squash bug also injects a toxin that expedites the plant's withering and death.
The squash bug has an ongoing life cycle. The adults we failed to eliminate last season will pass the winter under whatever shelter they can find - leaves, boards, stones, or debris. They will re-emerge as soon as the weather warms up (yes, just about the time those vulnerable baby squash plants are emerging). The adults mate soon after re-emerging and begin laying eggs in groups of a dozen or more. These eggs hatch in 10-14 days, and it only takes these new nymphs 4-6 weeks to reach maturity. So, all stages can be observed simultaneously throughout the season. How in the world do we control these multiplying monsters?
Let's just say that planning for control begins way before you plant the first seed. The very first line of defense includes several Systemic Strategies. Sanitation is a key measure. If adults over-winter under debris, get rid of all those hiding places. Next, plan to plant this year's crop where no squash or pumpkin grew last year; rotate your crops. While the bugs are quite capable of traveling, rotating and planting a little later will delay a bug population build-up. Companion planting is also worth a try, using repellent plants that deter the squash bug. They include catnip, tansy, radishes, nasturtiums, marigolds, bee balm and mint.
The second line of defense is Mechanical and Physical Strategies. The use of tightly secured barriers, such as floating row covers physically exclude the pests and prevent them from reaching the squash plants in large numbers. The covers can stay on until just before the female flowers appear. This is not labor intensive, and starts you out ahead of the war games. Another physical strategy is the use of kaolin clay products. Sprayed on the plants regularly at least every two weeks it forms a light-colored protective coating believed to deter the squash bug. Last season, I gave it a try. I sprayed half of my squash crop (both summer and winter) with kaolin and left the other half unsprayed. The results were measured daily by inspecting all leaves and counting (and removing) the number of squash bugs found in each area. While the method is definitely labor intensive (mixing and spraying every two weeks to cover new growth), I found 2/3 less squash bugs inhabiting the Kaolin covered plants. However, if I hadn't found and removed them by vigilant inspections, how much would they have multiplied?
The third line of defense is the Material Strategy. This includes biologicals and botanicals, such as sabodella, insecticide soaps and neem oil. Success with these is most effective on the nymphs. Once the adult bug emerges, this line of defense is not very effective.
Let me add my own suggestion to what all the experts have suggested: Vigilance. Checking under all the leaves each day will reward you with finding and removing the first line of adults, busily mating. Get rid of these, and their life's production cycle is interrupted,. With all these defense options to be tried, I wish you a great squash growing season!