Cottonseed Oil Helps Malathion
Fight Boll Weevils
June 30, 2000
Adding refined cottonseed oil to
malathion sprays makes them more effective at controlling boll weevils in
cotton fields, Agricultural Research
Service scientists have found.
The boll weevil has been a hole in the pocket for southern
cotton farmers, causing billions of dollars in damage, crop losses and control
costs since entering the United States in the late 19th century. For this
reason, the U.S. Department of Agriculture
started the Boll Weevil Eradication Program in 1978 to help farmers battle this
The first year of the program begins in a particular area in August and
continues into October. During this time, growers spray 8 to 12 applications of
malathion to reduce the number of weevils entering diapause--the dormant period
in the pests life cycle.
To reduce malathion application costs for boll weevil eradication,
researchers with the ARS Application and Production
Technology Research Unit in Stoneville, Miss., evaluated different oil
mixtures for their ability to enhance the effectiveness of malathion.
They found that, during July, boll weevil mortality from an 8-ounce mixture
of malathion and cottonseed oil was the same as from a 10-ounce application of
undiluted malathion for the first 2 days after application. In August, however,
there were no differences in mortality until 5 days after application.
Their research also showed that malathion accumulates on the surface of
mature cotton plants after repeated application during rain-free periods in
August. The researchers say this implies that the interval between applications
during this part of the growing season could be increased, thus reducing the
number of applications and the cost of eradication.
The 8-ounce mixture of malathion/cottonseed oil is 20 cents per acre per
application cheaper than a 10-ounce application of malathion--a substantial
Scientific contact: Joseph E.
Mulrooney, ARS Application and Production Technology Research Unit,
Stoneville, Miss.; phone (662) 686-5342, fax (662) 686-5372,