2021 Volume 2021 Issue 132 Pages 33-44
The mulberry scale, Pseudaulacaspis pentagona (Targioni-Tozetti), is one of the most important pests of tea. The scales inhabit the leafy parts of the branches; therefore, pesticide applied from above may not reach the scales efficiently. To determine the most effective method of pesticide application using riding-type sprayers, water-sensitive paper was placed in tea bushes, and different volumes of water were sprayed over the bushes. Two sprayer models, each with two types of nozzle, were tested using the elevated boom nozzles alone, the specialized ground-level anti-scale nozzles alone, or the elevated boom nozzles together with the anti-scale nozzles. After spraying, the proportion of the paper covered with water was measured. For both the KJS4-BR model (Kawasaki Kiko Co., Ltd., Shimada, Japan) and the OMS-7F model (Ochiai Cutlery Manufacturing Co., Ltd., Kikugawa, Japan), the proportion of the paper covered by the elevated boom nozzles and anti-scale nozzles together was equal to or greater than that covered by either nozzle type alone, regardless of spray volume. This suggests that combined use of the elevated boom nozzles and anti-scale nozzles may effectively promote adherence of pesticide droplets to tea branches. In most cases where both nozzle types were used, the deeper and more inward the placement of the paper in the tea bush, the larger the proportion of the paper covered. Based on these results, it appears that combined use of the elevated boom nozzles and anti-scale nozzles is optimal for scale control.
