When I hear stories of gardeners abandoning cucurbits (AKA zucchini and other squash) on people’s doorsteps, I wish this was my problem. Why do I have trouble growing these plants? I don’t use pesticides. If you want to kill some bees and reduce your yield, treat your zucchini plants with an insecticide.
My first job at MU was on an EPA program called “Rebuttable Presumption Against Registration.” Our job was to send the EPA data on the pros and cons of using various pesticides. Essentially asking whether the risk was worth the benefit. Based on that experience, when it comes to flea and tick control I’m on-board with man-made chemicals. (I apologize to my Kitty Boys but there is nothing worse than a home flea infestation). However, putting chemicals on something I’m eventually going to eat just doesn’t happen unless it’s absolutely, positively necessary. That means that to harvest a lot of squash and other cucurbits I have to do some serious plant monitoring. My methods are working pretty well, as we have gone from losing our plants to insect pests by the first of July, to harvests still going on in September (knock on wood)! My freezer is filled every year with my version of a delicious summer squash bisque! (If you want the recipe email me!)
Figure 1. Squash bug approximately ½ to ¾ inch long. Photo, Keith Weller, USDA.
When it comes to growing squash or cucumbers around here, the big problems are squash bugs, squash borers and cucumber beetles. Anyone who has ever grown squash two years in a row knows what a squash bug looks like (Figure 1). The squash borer adult is more elusive (Figure 2). Our cucumber beetles tend to be the twelve-spotted variety (Figure 4).
Figure 2. Squash borer approximately ½ to ¾ inch long. Photo, Jesse Christopherson
Here’s what is working for me with the squash bugs and borers.
First, I clean up my garden waste after the first hard freeze in the fall. This way I’m removing overwintering sites for many pests including the squash bugs. Then in the spring, I plant two separate patches with summer squash as far apart as possible and leave 4 or 5 plants per mound. Depending on your garden size I recommend planting your cucumbers and winter squash in the same fashion. It may be crowded at first but it is inevitable in gardens over a year old that one of these pests will kill some of your plants.
Most mornings I get up early (it’s really nice out then — it’s cool, the birds are singing), I put on my flexible garden gloves, take my 5-gallon bucket of soapy water and an aerial (butterfly) net to the garden. First I sneak up on my plants looking for adult squash borers laying eggs near the base of my plants. It’s their larvae in the plant stems that make your otherwise healthy zucchini plant suddenly collapse and die. If you see one you have to act FAST. I swoop the net on top of it and then hold up the end of the net so they will fly up into it. Catching them on the wing is more difficult, but when you succeed it’s thrilling (well at least for a 62 year-old woman).
Figure 3. Squash bug eggs and immature squash bugs. Photo, Zsofia Szendrei, Michigan State University
Then, when I’m done scouting for those I start looking for adult and immature squash bugs, but more importantly squash bug eggs (Figure 3). These are usually laid in clusters anywhere on the plant. When I see the eggs or immature bugs on a plant leaf or stem I remove part or all of that leaf and plunge it under the water in my bucket. If I see an adult or near-adult bug I crush it with my gloved hand or step on it. I’ve killed thousands and never been hurt, so don’t be afraid to do it.
Figure 4. Spotted cucumber beetle approximately 1/3 inch long. Photo, DrPhotoMoto
Unfortunately I don’t have much luck removing cucumber beetles by hand. The damage they do to my cucumbers by feeding is negligible, but they do a lot of damage by transmitting a bacterial wilt, which is why I plant several vines on each patch. Usually one of them makes it! For other ideas on how to deal with these pests, take a look at the websites below.
Missouri Botanical Garden – Cucumber beetles
Missouri Botanical Garden – Squash borers
Missouri Botanical Garden – Squash bugs