Atomization and Application of Biopesticide Formulations

Biopesticide materials are increasingly used in forestry, agriculture and vector control. Their low mammalian toxicity and low environmental hazard potential has encouraged researchers and applicators to evaluate their control potential for a variety of insect pests. However, the resulting formulations of these materials, primarily Bacillius thuringiensis (Bt) and baculoviruses, have not been easy to use under field conditions. Additionally, their physical properties and equipment for applying them did not meet the desired drop size of 80 to 100 micrometers vmd (or D_v.5)that biologists thought were most desirable.

Formulation and drop size studies have been initiated to determine the most suitable atomizers, rotary and hydraulic, to use with the various formulations being developed. Physical properties of these formulations indicate the usual reduction in surface tension to about 50% that of water, which tends to reduce the drop size produced compared with that of water. Density does not appear to be a factor of concern, but viscosity, particularly of the virus formulations, may be over 100 mPa∙s and may cause flow problems in spray equipment or produce a large drop size resulting in poor distribution and reduced control. Several formulations were tested along with various atomizers and data on these are shown.