2025 Volume 67 Pages 1-9
The damage caused by anthracnose is a problem in organic tea fields in Shizuoka Prefecture, Japan, highlighting the need to develop an effective method for anthracnose control. Therefore, we developed a pest-cleaning machine designed for pest control in organic tea fields. This machine can remove a certain number of anthracnose-diseased leaves from the canopy of tea plants by blowing air while simultaneously spraying agrochemicals, such as copper fungicides. Therefore, we determined which treatment schedule using the machine was effective for controlling anthracnose in a tea field at the Tea Science Research Center, Shizuoka Prefectural Research Institute of Agriculture and Forestry (Kikugawa City, Shizuoka Prefecture). In machine-treated plots (without simultaneous copper treatment) before or during the sprouting period of each tea season, the preventive value against anthracnose before the plucking time in the second tea season and during the third tea season ranged from 42.9–53.4, and the number of anthracnose-diseased leaves was reduced by nearly half compared to untreated plots. Additional machine treatment before plucking or simultaneous copper treatment did not significantly affect the number of anthracnose-diseased leaves. We then evaluated the control effect of the machine on anthracnose in local organic tea fields in the two regions. At an organic tea field in Shimada City, Shizuoka Prefecture, the number of anthracnose-diseased leaves was lower in the machine-treated plots (without simultaneous copper treatment) during the sprouting period of each tea season and before plucking in autumn tea season compared to untreated plots (the preventive value: 32.3–47.0). At organic tea fields in Numazu City, Shizuoka Prefecture, the number of anthracnose-diseased leaves was also lower in the machine-treated plot (without simultaneous copper treatment) during the sprouting period of autumn shoots after pruning and before plucking in the autumn tea season compared to untreated plots (the preventive value: 53.1–83.3). This study revealed that the pest-cleaning machine treatment can suppress anthracnose, highlighting its usefulness and significance in controlling this disease in organic tea fields.
