Extension Report

Baldwin County Extension Office

302A Byrne Street

Bay Minette, AL  36507

Telephone (251) 937-7176 or

928-0860/943-5061 ext. 2222

FAX (251) 937-7285

Dr. Ayanava Majumdar

Extension Entomologist & Sustainable Agriculture Coordinator, Auburn University

February 15, 2011

Outsmart Insect Pests with Trap Crops!

Successful vegetable production in the Deep South is dependent upon the effective control of insect pests. Integrated pest management (IPM) is an important pest management system that emphasizes the use of alternative pest management tactics before using harsh insecticides in order to protect the environment. Trap cropping is one of the alternative pest management techniques that have recently sparked lots of interest among fruit and vegetable producers in Alabama. Trap crops can be used to manage a wide range of insects and it relies on the principle that insects are attracted to specific host plants for feeding and reproduction. In other words, trap crops are plants that will attract and hold an insect pest so that damage to the marketable main crop is kept to a minimum. Not all insects can be managed by trap cropping because insect host preference is specific. Also, trap cropping is not pesticide-free crop production. In fact, the success of trap crop strategy depends on the timely use of fast-acting insecticides on a trap crop to kill insect pests as soon they are detected. Commercial vegetable growers can use a range of older pyrethroids as well as the new selective insecticides (feeding blockers) for managing insects while they are in the trap crop; gardeners/backyard vegetable producers may manually remove pests from trap crops. By using trap crop and controlling pests with either insecticide or mechanical means, growers can cut back on the total amount of insecticides used every year on the main crop leading to a better quality produce. Other advantages of trap crops include preservation of natural enemies and environmental conservation. Some examples of trap crops include the following (this is not a comprehensive list): sweet sorghum, sunflower, okra, and buckwheat for stink bugs, soybean for Mexican bean beetles, collard for diamondback moths, sunflower for leaffooted bugs, canola and alfalfa for tarnished plant bugs, squash for squash bugs and cucumber beetles. A grower should first identify correctly the primary insect pest (consult an Extension personnel for help) and then choose a trap crop suitable for protecting the main crop. Organic producers and gardeners can also use biological insecticides with rapid knock-down for managing the pest in a trap crop.   

There are two ways of trap cropping: growers can either use same plant species as main crop/trap crop (e.g., early planted tomato ‘trap crop’ to protect a tomato ‘main crop’) or the trap crop and main crop could be entirely different plant species. Generally, the latter system is used commonly by growers because it creates biodiversity on the farm and reduces cost of trap cropping. Research suggests that no more than 20 percent of the total area be used for trap cropping in order to maximize economic benefits; it is prudent that growers evaluate the effectiveness trap crop on their farm by starting on a small acreage (10 percent) and then increase the area gradually to a manageable level. A dense, timely-planted trap crop will be more attractive to insects than a trap crop planted too thin or with a poor plant stand. Grow the trap crop on good soil because a trap crop grown on poor soil won’t be attractive to the target insect pest and that defeats the whole purpose. With a few exceptions (e.g., collard), the trap crop is typically most attractive to pest during flowering and fruit-formation stages.

Trap crop can be arranged in various designs and the layout will depend upon the target pest. Growers can use various types of pheromone traps to monitor insect pests on their crops (remember to keep records!) and determine the peak activity period, insect pressure levels and the general direction of infestation or migration. Pheromone traps can also be used in conjunction with trap crops for mass trapping, for example, diamondback moths may be mass-trapped in a trap crop like collard in order to reduce the number of moths landing in the main crop. Perimeter trap cropping involves planting the trap crop all around the field of a main crop; this method is very popular for arresting the movement of insects with short migratory flights, e.g., pepper maggots, squash bugs, and striped cucumber beetles. By treating the perimeter trap crop, growers in some parts of the country have reported over 90 percent reduction in pesticide use that saved time and money in the long-run. Early-planted ‘Blue Hubbard’ summer squash is one of the most effective perimeter trap crops for reducing cucumber beetle and squash bug infestation in main crops like watermelon, cantaloupe and cucumber. Row intercropping is another planting method where two plant species are planted in close proximity for a beneficial interaction; row intercropping generally involves alternating rows of trap crop within the main crop. Row intercropping may be used if pest pressures are high or for intercepting extremely mobile species of insects. For example, organic growers in California plant wide strips of alfalfa (trap crop) within 30-40 rows of strawberries to attract tarnished plant bugs which were collected by using a tractor-mounted vacuuming device. By devoting less than 3% area to row intercropping, those California producers reduced the abundance of tarnished plant bugs by 90 percent. Thus, these and other examples of trap cropping indicate that an alternative pest management strategy can work if it is carefully implemented and integrated with other IPM tactics. Trap cropping involves planning and guidance. Commercial vegetable producers, row crop producers, homeowners and gardeners can join me for further discussion on the trap cropping system and other critical IPM issues by joining the ‘Alabama Vegetable IPM’ or the ‘Alabama Peanut IPM Program’ pages on FACEBOOK. I can also be reached by emailing bugdoctor@auburn.edu. Have a Happy Cropping Season in 2011.

Email address: azm0024@auburn.edu

Phone: 937-7176 or 943-5061, ext. 2222

The Alabama Cooperative Extension System (Alabama A&M and Auburn Universities) in cooperation with the U.S. Department of Agriculture is an equal opportunity educator and employer.