. Canadian journal of agricultural science. Agricultural Institute of Canada; Agriculture. 60 SCIENTIFIC AGRICULTURE October 1920 showed the disease on the succeeding crop of sunflowers in 1921, and it was en- couraging to note that the disease was not conspicuously worse in 1921 than in 1920, despite the opportunities for spread of the fungus in tlic field, the presence of infect- ed debris in the field, and a damper season in 1921. The losses were, however, con- siderable in extent, and tlie disease is suf- ficiently threatening to the sunflower crop to deserve careful attention. The Sclerot
. Canadian journal of agricultural science. Agricultural Institute of Canada; Agriculture. 60 SCIENTIFIC AGRICULTURE October 1920 showed the disease on the succeeding crop of sunflowers in 1921, and it was en- couraging to note that the disease was not conspicuously worse in 1921 than in 1920, despite the opportunities for spread of the fungus in tlic field, the presence of infect- ed debris in the field, and a damper season in 1921. The losses were, however, con- siderable in extent, and tlie disease is suf- ficiently threatening to the sunflower crop to deserve careful attention. The Sclerotinia lives over winter in the soil, as is indicated by the fact that the same areas \vere affected in 1920 and 1921. Affected sunflower plants rarely produce seed, and no evidence was obtained that. â¢â Figure 3.âLeisons caused by the parasite, and externally produced sclerotia on sun- flowers found affected in the field, August 19th. 1921. tfte seed carries the organism. Tissue cul- tures were made in 1920 from the stem is, 36, 24, 8, 6 and 3 inches above affect- ed areas on stems and from opposite the tip of a lesion wliich extended further up one side of the stem than the other. In none of tliese cases was Sclerotinia myce- lium obtained. The organism may, how- ever, be obtained readily from tissue cul- tures from affected areas. It is evidently not systemic in affected plants. Tnoculations were made during the win- ter of 1920-'21 upon sunflower and other plants in the greenhouse, and upon various vegetables. Cultivated sunflower plants about one foot high were killed by inocula- tion of the base of the plants with mycelium from a pure culture of the fungus and Sclerotia developed within the stem. The lack of light allowed only a slight growth of the plants. In the laboratory inocula- tions, a culture of the fungiis into carrots and parsnips readily produced rot, and a considerable rot was produced upon potato tubers. Onions rotted onlj' slightly. Tur- nips and beets di
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