Abstract
Cylindrocladium black rot (CBR) of soybean is seen all over the world. Symptoms of CBR include chlorosis of the root, followed by complete wilting of the plants, and death. It is difficult to remove the pathogenic fungi, Cylindrocladium parasiticum, for its facultative parasitism. The control by cultivation and breeding of resistant varieties has been tried, but it is not yet enough. C. parasiticum exist in every soybean field of Japan, but actual disease incidences are usually not so high. C. parasiticum infect most of soybean plants up to 4 week after sowing, but the symptoms appear from 8 week after sowing. These facts suggest that soybean intrinsically has the resistant ability against to CBR. This histological study revealed that additional periderm developed and that it functioned enough to prevent the infection of C. parasiticum. We will discuss the conditions and the mechanisms for CBR outbreak.
