|Howard, Kevin - DELTA & PINE LAND, INC.|
|Jones, R. - APHIS|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 1996
Publication Date: N/A
Interpretive Summary: Millions of acres of cotton in the Boll Weevil Eradication Programs are treated with a 16 oz/acre volume of ULV malathion by aircraft. However, there are areas around lakes and towns within the eradication zones that cannot be treated by aircraft. The only other means of application is by ground sprayer; however, a 16 oz/acre volume is too low to be applied by conventional hydraulic ground sprayers. Therefore, the Boll Weevil Eradication Programs desperately needed a means of applying ULV malathion by ground sprayer. The research reported here adapted an air-assisted sprayer for applying ULV malathion and evaluated it for boll weevil control. The results of this research showed that the air-assisted sprayer provided effective control of boll weevils. More importantly, this research demonstrated that 12 oz of ULV malathion is just as effective in controlling boll weevils as the 16 oz rate. As a result, the rate used in the Eradication Programs has been reduced. This 25% reduction in rate should result in savings of millions of dollars by U.S. farmers. In addition, because the ULV malathion formulation has a longer residual efficacy, the time interval between sprays can be increased resulting in fewer trips over the field and additional savings in time and labor. Since the initiation of this research, approximately 20 ground sprayers have been equipped with this air-assisted spraying system for use in the Eradication Programs. According to APHIS personnel, the boll weevil could not have been eradicated from the Tennessee River Valley in Alabama without this spraying system.
Technical Abstract: During 1994 and 1995, tests of ultra low volume (ULV) applications of insecticides conducted on cotton at Stoneville, MS evaluated the effectiveness of ULV malathion applied with a new technology in ULV ground application; the air-assisted ULV ground sprayer. Two tests conducted in 1994 determined the effectiveness of ULV malathion (91%) and established effective malathion rates against boll weevils, Anthonomis grandis grandis Boheman. An emulsifiable concentrate (EC) formulation of azinophosmethyl was used as a standard. In 1995, ULV malathion (95%) was applied at 1.37 and 1.02 kg[AI]/ha plus cottonseed oil in a total volume of 1.17 l/ha. These treatments were compared to a 1.12 kg[AI]/ha rate of an EC formulation of malathion applied with water in a 46.8 l/ha volume. In the 1994 comparison test, ULV malathion treatments resulted in about 70% mortality, throughout the 48 hour test period, while mortality from the azinophosmethyl steadily decreased from 71% at 4 hours after treatment (HAT) to 12% at 48 HAT. In the 1994 rate test, 1.30 and 0.98 kg[AI]/ha of malathion produced comparable mortalities to azinophosmethyl at 0.28 kg[AI]/ha. In 1995, mortality at 48 HAT was highest for the 1.37 kg[AI]/ha rate (90%) followed by the 1.02 kg[AI]/ha rate (54%) and lowest in the EC formulation treatment (21%). The air-assisted ground sprayer permitted ULV application of malation and reduced the rate of ULV malathion required for effective boll weevil control.