Lateral move chemigation of Lorsban-4E on field corn

A 150 m (500 ft) lateral move machine was equipped to apply Lorsban-4E (chlorpyrifos) at a rate of 2.2 L/ha (0.24 gal/acre) while transversing a corn field at a speed of 2 m/min (6.6 ft/min). Four formulations, utilizing additions of either water, soybean oil, light grade petroleum oil or a nonionic surfactant, were evaluated. Leaf and soil samples obtained throughout the field were analyzed in a GLC for Lorsban concentration. Of the four formulations, soybean oil was the most effective in securing Lorsban-4E to the foilage and minimizing the amount washed down to the soil surface. Supreme oil and the nonionic surfactant were the next most effective in sticking Lorsban to the foliage, whereas water was least effective. Foliage samples taken from transects across the field indicated that application was fairly uniform over the first three quarters of the lateral's length but decreased 20-40% in the last quarter. Time samples indicated a rapid decline in Lorsban concentration over the first 24 h following application and a gradual decline thereafter to near zero concentration after the seventh day.