A Salad That Diamondback Moths Can’t Resist

What’s a good way to stop hungry diamondback moths from nibbling on a farmer’s cabbage, broccoli, kale and other cole crops? Agricultural Research Service scientists have an answer: give the pests a heaping serving of collard greens.

Entomologist Everett Mitchell, at the ARS’ Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla., says giving the pest collards spoils its appetite for cabbage. The moths can’t resist the all-you-can-eat collards when they’re planted completely around cabbage field edges, a strategy called trap cropping that could also work to protect other cole crops.

Invading diamondbacks stop and deposit their eggs on the collards rather than on adjacent cabbage plants. Diamondback populations continue to re-cycle in collards as long as plants remain green and continue to grow.

Diamondback moths, named for the diamond-shaped markings on their wings, are becoming resistant to many chemicals. Spraying pesticides can be costly, ranging from about$10to $21 an acre for each application, depending on which pesticides are used. It typically costs growers $80 to $168 per acre or more each season to produce a crop.

Mitchell conducted recent experiments on farms in northeast Florida that showed the moths prefer to feed on highly fertilized collard plants. He tested this approach for more than two years. In all cases, he says, damage to cabbage by diamondback moth larvae was minimal.

This simple, low-tech, cost-effective method also reduces pesticide use. Cabbage fields surrounded by collards required 75 to 100 percent fewer sprays to control diamondback moth than fields treated conventionally with pesticides.

An in-depth article on this research appears in the March issue of Agricultural Research magazine. The story is also on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/mar99/diam0399.htm

ARS is USDA’s chief research agency.

Scientific contact: Everett Mitchell, ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Fla., 32604, (phone) 352-374-5710, (fax) 352-374-5804, [email protected].