Abstract
In the present paper the writer intends to report on the results of the author's pathological and physiological researches on culture filtrates of the causal fungus of black spot disease of Japanese pears, Alternaria Kikuchiana TANAKA.
1) The results of biological experiments on toxic action of culture filtrates of the fungus to host plant were described.
2) The pathogenicity of culture filtrates of 25 species and 8 strains of phytopathogenic fungi belon-ging to genera, Alternaria, Fusarium, Colletotrichum, Macrosporium and Venturia was tested. It was decidedly considered that the characteristic symptom of the disease appears only by Alternaria Kikuchiana.
3) Effect of deficiency of some elements in synthetic nutrient solutions on the pathogenicity of Alternaria Kikuchiana and toxicity of culture filtrates, was studied. From the results, it seems that there is an exact relation between the occurreence of the disease and culture filtrates and also the protoplasmic speciality of host plant.
The protoplasmic speciality of host plant is remarkably sensitive to culture filtrates of the causal fungus, accordingly, in the present paper the term, HYPERSENSITIVE DISEASE OF PLANTS is newly suggested by the writer. (Laboratory of Phytopathology, Faculty of Agriculture, Tottori University)
