Indiana Plant Diseases, 1921 



177 



sporulation on the lesions on the leaf blades but none on the petiole 

 lesions. 



Celery. — The heat of July was favorable to the Fusarium yellows 

 disease which is present in much of the celery soil, but August and 

 September were not as favorable to the disease. It was noted in In- 

 dianapolis market gardens where the growers still grow the susceptible 

 Golden Self-blanching variety and near Lafayette. The use of the re- 

 sistant Easy-Bleaching variety has saved the celery industry near 

 Goshen. Laboratory studies of the temperature relations of this fungus 

 in culture show that it makes practically no growth at 10° C and 

 35° C, that it grows well at 16° and 20° C, better at 30°, and best at 

 25° and 27° C. This would indicate that a high soil temperature should 

 aggravate this disease, and previous observations on this disease in the 

 Kalamazoo, Mich., celery marshes in 1914 indicate that such is the case. 



As usual, early blight, caused by Cercospora apii, was very de- 

 structive and was killing much of the older foliage in the celery patches 



Fig. 5. Fusarium rot of cantaloupe in ripe fruit. 



near Indianapolis and Lafayette in July. In a truck garden in Henry 

 County, July 20, this disease appeared to be worse on the Golden Self- 

 blanching variety than on the Easy Bleaching. The Goshen fields were 

 visited on September 22, and in the crop that was then being harvested 

 early blight was so severe as to necessitate stripping off of many leaves 

 that otherwise would have been salable. In many cases this disease was 

 directly responsible for the loss of three or four large stalks per plant. 

 Laboratory studies of the effect of temperature upon the growth of this 

 fungus have shown that very little growth occurred at 10° C and 35° C, 

 and that growth was good between 16° and 30°, with an optimum at 

 27° C. Spore germination occurred readily in both water and prune 

 decoction at temperatures from 10° to 30° C. Septoria apii, the fungus 

 causing late blight, which is less destructive in Indiana than early 

 blight, was found to grow well only between 16° and 27° C. and to 

 grow best at 20° C. Spore germination occurred readily between 16° and 

 25° C. Thus Sejitoria apii has a lower optimum temperature for growth 

 and a narrower range for vigorous spore germination than is the case 



