1.The mycelium of the five cultural strains grew under wide range of temperature and the optimum occurred at between 24° and 28°C. At 34°C-36°C there was only a faint growth.
2 The mycelial growth of four cultural strains (No.3, No.4, No.5, No.6) was fairly good on potato agar, oat-meal agar and Czapek agar, but their growth was very poor on Richard's agar and apricot agar. The spore formation on the apricot agar was not good either. Strain No.9 showed good mycelial growth on Richard's agar, but not on Czapek agar, and no spore formation took place in any of the media used in this experiment.
3. Thermal death points for mycelium and conidia in moist heat were as follows: Strain No.3 and No.5: 55°C for 5 to 15 minutes. Strain No.4 and No.6: 61°C for 5 to 15 minutes. Strain No. 9: 49°C for 5 minutes.
4. Cellulose and starch decomposing abilities of the causal organisms varied with the cultural strains and they were correlated with the pathogenicity of the cultural strains. The cellulose and starch decomposing abilities of the causal fungus are, therefore, considered an index for classification of the fungus.
5. As based on the morphological and physiological characters and pathogenicity the causal organisms that causes the Fusarium bulb-rot of tulip is considered consist of strains of Fusarium oxysporum ScHL. of section Elegans in the genus Fusarium.
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