Disease incidence trend of zoysiagrass in Japan based on diagnosis results

Abstract Based on the results of disease diagnoses from 2013 to 2022, trends in the incidence of zoysiagrass diseases in Japan were examined. Zoysia decline, large patch, and necrotic ring spot were the most frequently observed diseases, in that order. These were followed by patch with white leaf and sheath, Pythium blight, Rhizoctonia patch, and dollar spot. Necrotic ring spot, Rhizoctonia patch, Zoysia decline, and circular poor growth of zoysiagrass in spring (CPG) were likely sampled more frequently because these diseases occur at the same time of year and are challenging to identify in the field. In recent years, the number of samples for necrotic ring spot and Zoysia decline has decreased. On the other hand, the number of samples for CPG has not changed. The factors that cause the occurrence of CPG remain unclear, so it will be necessary to study the conditions under which the disease occurs in the future.