Gardeners are known for their generosity. We enthusiastically share our plants, seeds, and especially home-grown produce with others (here, have some zucchini!). But share them with bugs? Well, generosity has its limits. There are few things as aggravating as seeing bugs chowing down on our lovingly tended spinach, corn, or cucumbers.
Since we’d rather not share the fruits of our labors with insects if we can help it, gardeners turn to options that eliminate them. These options are often chemical in nature. Those of us who garden organically, however, don’t want to put harmful pesticides on our plants. For us, there is an effective organic technique that can control pests called trap cropping.
Trap cropping is a technique whereby a plant (a tomato, for example) that is favored by a particular pest (say, a leaf-footed bug) is surrounded by plants that the bug finds even tastier (in this case, black oil sunflowers). The bug bypasses the tomato to snack on the sunflowers. They can then be picked off by hand, or the trap crop destroyed. (As a bonus, in this instance the sunflowers will also attract birds that will eat the bugs.)
Trap crops are a type of companion planting. Most companion planting is designed to keep pests away entirely. But trap crops don’t repel insects, they distract them, beckoning them to plants you can sacrifice so they stay away from the plants you want.
Some examples of trap cropping include planting blue Hubbard squash to keep squash bugs (Anasa genus) and squash vine borers (Melittia cucurbitae) away from butternut and summer squash, cantaloupe, and watermelon.
Cucumber beetles (Diabrotica and Acalymma genera) love amaranth and blue Hubbard squash. Planting these will help keep them away from your cucumbers, cantaloupe, watermelon, squash and pumpkins.
Apples, peaches, tomatoes, peppers, and corn all fall victim to stink bugs (order Hemiptera). Use black oil sunflowers, amaranth, or buckwheat as a trap crop.
Trap crops should be planted at least 10 feet away from and two weeks earlier than the main crop, if possible. And only use trap crops if you’ve had a pest in the past. Don’t use them as a preventative or you may end up with bugs you’ve never had before.
Maintain the trap crop the way you would any desirable crop. It needs to stay healthy so it appeals to pests; if it isn’t, they’ll just switch to your main crop. Don’t wait for pest populations to build up. Remove insects and their eggs when you see them to keep them from reproducing or reaching numbers that send some to the main crop.
Finally, as effective as they can be, trap crops don’t work on every pest insect. Use them along with other control methods. This article from Washington State University has more information on using trap crops.
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