Abstract
1. In the present paper the writer deals with the results of the experiments on the resisting power of urediospores of Puccinia triticina to low temperatures. The urediospores to betested were collected in May from wheat leaves in the field.
2. The germination percentage of urediospores which were kept under -10°C in dry condition, reduced rapidly after one day and almost lost their germinabiliay after 60 days, when they were brought into the refrigerator directly from room temperature (ca. 20°C). In this case the spores were not in perfectly dry condition, because of high moisture content in the interior of the refrigerator.
3. The urediospores in water suspension kept in the refrigerator seemed to die more rapidly than those in dry condition. This is probably due to freezing of water. The result of the experiments on the present fungus, however, was not so clear as that on Puccinia simplex in the previous experiments.
4. The resisting power of the urediospores to the low temperature of -10°C increased remarkably, as was noted when the affected leaves were incubated under a temperature of -4°C, and them the water suspension, of the spores brought into the refrigerator of -10°C.
