The Relative Efficiency of Aerial Application of Ultra-Low-Volume and Emulsifiable Concentrate Formulations of Insecticides1

Abstract

Tests were conducted in 1966 to compare efficiency of applying insecticides as ultra low volume (ULV) and emulsifiable concentrates (EG). The ULV formulations were applied in volumes of from 1 pint to ½ gallon and the EG formulations were diluted with water to a volume of 1½ gallons. The ULV was applied with the ULV boom using the necessary numbers of 80015 tips and with a rotary atomizer. The EG was applied with a conventional boom. Flight heights of 20 and 5 feet were compared with both formulations. Efficiency of application was evaluated by droplet counts across the target area and for 1200 feet downwind, and chemical analyses of insecticide deposit in the 100-foot target area. Application to a precise target area was less efficient at a 20-foot than a 5-foot height of flight. The droplet count was much lower when insecticides were applied from the 20-foot height for about 100 feet downwind. Applications from the 5-foot height of flight were more efficient in control of deposit in the target area. There was no evidence of more droplets deposited from 300 to 1200 feet downwind with either formulation. More droplets per square inch were recovered in the target area with EC than with ULV concentrates. However, more insecticide was recovered from ULV applications than from EC. The larger droplet sizes (avg 150 µ) of ULV (with fewer droplets per square inch) resulted in from 2- to 4-fold more insecticide being recovered in the target area. ULV formulations applied in droplet sizes ranging from 100 to 200 µ drifted less than EC water diluted formulations. Results of these tests offer an explanation of the frequent reports that ULV formulations are more effective than EC. It may be that with ULV treatments, more insecticide reaches the desired area and less is lost to drift.