Abstract/Contents: | The major turfgrass diseases found in Japan are spring dead spot,Rhizoctonia large patch, and rusts with brown patch and Pythium blight occurring on bentgrass. Leaf blight, fairy rings, and snow molds occur on both Zoysia and bentgrass. Rhizoctonia spring dead spot occurs frequently on Zoysia grass particularly on fine leaved varieties and rarely on wild Zoysia grass. Infection occurs from the lower part of the plant near the ground in autumn when temperature falls to about 10C. In the following spring at the middle to the end of March when temperature rises over 15C and budding starts, white and roughly circular diseased patches 20-40 cm in diameter appear on the regions where growth of the turfgrass has delayed. This disease appears frequently on old dried turf where matting and thatching of the grass have taken place. Pythium spring dead spot occurs from the end of February through the beggining [beginning] of March, and random-shaped diseased patches a few square meters in size appear at the end of March through the beginning of April. Cultural control for these two types of diseases includes dispersion of mat and removal of thatch by renovation works; also, moderate watering in the dry season between late autumn and early spring is effective to prevent outbreaks. Application of chemicals 1-3 times during the period from October to December (temperature falls to about 10C) is recommendable, because infection takes place in this period. The chemicals being used are chloroneb wettable powder (WP) (x 500-1,000, 1 l/m2), thiuramthiophanate methyl WP (x 1,000 2l/mr), flutolanilpropiconazole-metalaxyl WP (x 300-500, 1 l/m2). Pathogens, symptoms, hosts, disease cycle and control of Rhizoctonia large patch, rust, brown patch, Pythium blight, leaf blight, fairy rings, and snow molds, are also summarized. |