Since trap crops take up some space, it never occurred to me that using these was a suitable organic pest control strategy for small home gardens. However, I have unexpectedly gained experience with a trap crop, since that is what my zucchini have turned out to be.
What is a trap crop?
A trap crop is one that is planted as a lure to pest insects, to keep them away from the main crop. Most trap crops are not expected to yield a harvest; instead, they are offered up to pests as an alternative to the main crop of a farm. According to SARE, trap crops are often planted around the edge of the main crop, forming a protective barrier that pests are likely to stay within. Trap crops can also be planted as a block or patch near the main crop.
According to University of Georgia, trap crops to work best when they make flowers before the main crop that they are protecting. When the plants are making flowers and fruits, that is when they are most attractive to most pests.
My zucchini plants function as a trap crop
You may have read the two recent blog posts about pests on my zucchini plants — one about squash beetles and the other about cucumber pickleworms. The squash beetles are really less of a problem, since there are only four or five each day for me to smash and the damage is limited to holes in the leaves. The pickleworms, though, are another story.
They have caused serious damage to the zucchini plants, ruining flowers and boring into main-stems and leaf-stems. The plants are still standing, but all hope of harvesting zucchini from this late-summer crop is gone.
This is the good news: my cucumber patch, planted in early August like the zucchini, has supplied several cucumbers for our meals already. Checking the cucumber plants nearly every day, I have found only a few squash beetles, grand-total, on the plants. It has been easy to find and smash the one-every-few-days beetles as I check on the garden.
In an instance of amazing good luck, my zucchini variety was so fast to mature that the plants made flowers more than a week before the cucumbers did. When the pests first showed up in my garden, the squash beetles and cucumber pickleworm moths flew past the cucumber patch, which didn’t have flowers, and attacked the zucchini plants in the half-barrel planter, where flowers and little squashes were abundant.
Even better, the cucumbers still do not show any pickleworm damage.
To combat any pickleworms that could be present, I have been treating both sets of plants with Bt for caterpillars (the one I am using is Thuricide), which is an organic pest control product. We have had a lot of rain, though, which washes the Bt away. I am not re-spraying my plants after every rain, so some days the cucumber crop is unprotected other than by the stronger allure of the zucchini plants.
At this point, the three remaining zucchini plants look hopelessly ragged, but they are still alive. I am leaving them in the garden for as long as they continue to work as pest-magnets.
The cucumbers remain pickleworm-free, but they are not perfect specimens. I had forgotten about the uneven pollination in hot weather that results in lumpy cucumbers. These are not headed for a pickle jar, which means the imperfect shapes are not really a problem.
Because of pest-concerns, I am harvesting the cucumbers while they are fairly small. This is a bit like harvesting tomatoes before they are fully red. I know that if I leave tomatoes in the garden to fully ripen, some pest (stink bug, chipmunk, mockingbird, etc) will notice the beautiful, ripe fruit and take a bite before I get a chance to enjoy the harvest, myself.
Unlike for tomatoes, there is not a flavor-reason to wait for more mature cucumbers. They taste pretty much the same at smaller sizes, and leaving them out in the pest-filled world seems a little like tempting fate.
So, as I ponder my next year’s garden, it is good to know that zucchini plants can use some unseen come-hither chemistry to draw pests away from the cucumbers.
This is the kind of garden-discovery that any of us can make. I have been growing food in this yard for more than 25 years, and I learn more about gardening every year. And even though there are pests, the garden is producing good food. This is part of the joy of gardening!