Physiologic Races of Pellicularia Sasakii in Taiwan

Abstract

Sheath blight disease incited by Pellicularia sasakii on rice plants is of the second importance to blast in distribution, as well as damage for the rice culture in Taiwan (Hashioka 1951). Under the present situation in Taiwan, the japnica type of rice is more susceptible. Yield loss from this disease is around 14-17% (Lo 1961). According to Lo (Personal communication), the loss due to the blast disease might have been exceeded by the scierotial sheath blight which has become increasingly prevalent in recent years (Chiu 1962). Sawada (1912) stated that the fungus might be able to infect a diverse number of plants, 47 species belonging to 4 families in Taiwan; 60 species belonging to 16 families in Japan. Matsumoto (1934) reported that there were 16 strains of the fungus collected in Taiwan from various hosts, including rice, sugarcane, groundnut, french bean, cowpea and camphor. Nakada and Kawamura (1939) pointed out that there were 16, 9 and 3 biotypes observed according to the cultural characteristics of the fungus on Czapek’s, Potato sucrose and dried plum agar, respectively. They also stated that the suscepts attacked by this parasite were about 188 species of 32 families in Japan. In consideration of the information stated above, one can presume the exi-stence of many physiologic races of the fungus in nature. For this reason an attempt on studies of the feasible existence of different races in Taiwan have been made in Department of Plant Pathology at Taiwan Agricultural Research Institute since 1957. In the present paper, experimental evidence confirmed the existence of physio-logic races of P. sasakii in Taiwan. 1. 自宜蘭、臺北、東勢、嘉義、屏東、臺東等地區，採集稻紋枯病害標本。經人工純系分離後，在馬鈴薯培養基上鑒別其培養型，並於溫窒內舉行人工接種。所選用十六鑒別稻品種係本研究室供鑒定稻熱病菌生理小種所用者。 2. 305 個純系分離之稻紋枯病病原菌，在馬鈴薯培養基上，以其菌絲之生長，培養基之色澤，菌核之形成日期、數目、色澤、形狀及在培養皿內之位置等特性，可分為七種培養型。 3. 根據以上七種培養型中，各選出一菌號，接種於選定之鑒別稻品種上，得到六種病原性不同之生理小種，即可分類為 1 , 2 , 3 , 4 , 5 及 6 等小種。 4. 在十六鑒別稻品種上，在來稻之抗病性高於蓬萊稻。在來稻中，陸稻比水稻更顯著。