Comparison of two methods for estimation of spray deposits after application of microbial pesticides

The effectiveness of two methods for the determination of deposition of mycopesticides on hemlock trees by spray application was compared. One method employs water and oil sensitive paper cards; the other uses a combination of two adhesive tapes (scotch tape) with different adhesive properties. Two fungi, Beauveria bassiana and Lecanicillium muscarium, and three fungal formulations based on whey, oil, and whey together with oil were used to evaluate the efficacy of the two methods. The new method has shown the certain advantages in comparison with the traditional method which is based on the sensitive paper cards. Generally, number of droplets counted was greater in the case of adhesive tape utilization. These observations were noted for the two entomopathogenic fungi. However, different results were noted for the three different types of fungal formulations. The presence of conidia was observed in all three formulations using adhesive tape. The number of conidia localized on hemlock twigs was affected by fungal formulation. The adhesive tape method allowed counting more droplets than the sensitive cards. Other advantages of the adhesive tape method include the ability to observe the outer appearance and internal structure of the droplets and to count fungal propagules directly on the leaf surfaces.