What are trap crops? Trap crops are plants that are planted next to a higher value crop so as to attract pest as either a food source or oviposition site, thus preventing or making less likely the arrival of the pest to the main crop (= cash crop). Insects congregated in trap crops can be more easily attacked by natural enemies and/or killed by insecticides or by other physical means. In other words, trap cropping functions by concentrating and/or killing the pest in the border area, while reducing pest numbers on the unsprayed cash crop. Plant species or cultivar used needs to be more attractive to pest than crop is.
Advantages: By using trap crops farmers can: (1) lessen pesticide use and decrease costs, (2) preserve indigenous natural enemies, (3) improve crop’s quality, and (4) help conserve the soil and environment.
Tips for successful trap cropping:
1. learn to know and identify the pests and their natural enemies,
2. make a farm plan to guide you on where and when the trap crops will be planted,
3. monitor your plants regularly,
4. immediately control the pests that are found in your trap crop, otherwise they will serve as a breeding ground,
5. if needed, be ready to sacrifice your trap crop as an early crop and destroy them as soon as the pest infestation gets too high, and
Examples: (1) In Massachusetts, 6 butternut growers planted a Blue Hubbard border around butternut squash fields that ranged in size from 2 to 6 acres. These 6 fields were compared to conventional butternut fields where beetles were controlled with full-field insecticide sprays. Fields were scouted twice weekly until first leaves, then weekly until flowering. Borders were sprayed at the first arrival of the beetles. Cucumber beetles were only found in the trap crop and insecticides were only applied to the perimeter trap crop. As a result, 85% less insecticide was applied. (2) In Missouri, a farmer in St. Peters was able to prevent cucumber beetles from eating his indoor cucumber transplants by using Blue Hubbard planted in pots and placed outside of his high tunnel. Four potted plants congregated hundreds of beetles while none was found inside the high tunnel. Research led by Dr. Piñero is being conducted in this area for the benefit of Missouri vegetable farmers.
Other examples of specific trap crops include the following:
Cucumber beetles use Blue Hubbard squash – plant Blue Hubbard two weeks before main cucurbit crop, can apply systemic insecticide to kill arriving beetles
Colorado potato beetles use potato variety Superior (grows well in cool weather) – plan the trap crop between last year’s and this year’s fields (near overwintering sites)
Squash bugs use squash – Main crops: zucchini, watermelon. Can treat the trap crop with an insecticide to control an infestation
Flea beetles use Chinese Southern Giant Mustard (Brassica juncea var. crispifolia) – Main crops: cabbage, broccoli or cauliflower. Reseeding of the trap crop may be necessary.
Diamondback moth use yellow rocket – Main crops: cabbage, broccoli and cauliflower. Attracts moths, inhibits larval development. Insecticides may not be needed as natural enemies may control the pest population.
European corn borer and fruitworm use corn (sweet or field) – Main crop: pepper (for Europena corn borer) and tomato (for fruitworm).