Indiana Plant Diseases, 1921 181 



ture upon spore germination show that good germination occurs at 

 4°, 9° and 16° C and practically none at 20° and above. The most 

 prompt germination (within three hours) occurred at 9° C. This indi- 

 cates that a very low temperature is necessary for infection with this 

 fungus and may explain why it is worse in the winter crops than in 

 the spring crop. 



Botrytis rot of the older leaves and stems was found in the spring 

 hothouse crop, and drop due to Sclerotinia libertiana occurred rather 

 generally in greenhouses. It was noted in the spring crop and re- 

 ported very destructive in mid-winter in one Indianapolis greenhouse. 

 A trouble resembling rosette due to Rhizoctonia was noted in the field 

 crop in September. 



There is considerable difficulty in the greenhouse crop with a marked 

 stunting of the plants. No root or stem lesions are associated with 

 this trouble and it may be due to the use of a poor quality of soil 

 or to a harmful accumulation of soil salts in the surface layers. 

 Leaching by surface watering and better under drainage should correct 

 the latter condition. 



Oats. — Jackson reports that there has been somewhat of an increase 

 in the prevalence of the smuts this season owing to a less consistent 

 practice of seed treatment than has been the case in previous seasons. 

 Gregory reports smut losses varying from one to as high as 35 per cent. 

 Jackson and Mains attribute considerable loss in yield to crown rust 

 (Puccinia coronata) in central Indiana and Mains reports that there was 

 a very slight amount of stem rust (P. graminif;) this year. Hosmer 

 found no stem rust in his surveys made in connection with the barberry 

 eradicat?ion work. The hot dry weather of this season was very un- 

 favorable to oats. 



Onion. — Gregory found smut caused by Urocystis cejndae very de- 

 structive in the onion set crop on three farms in Lake County, causing 

 as high as 50 per cent loss, and growers informed him that the disease 

 was present on about twelve other farms in the county. On June 16, 

 Gregory found a light infection of onion smut in a field in Jasper 

 County. Red onions seem to show some resistance to this disease. In con- 

 trol tests with the formaldehyde drip on the seed drill, Gregory reported 

 very favorable results, the yield of graded sets being doubled and the 

 amount of undesirable over-sized bulbs reduced one-half. 



Smudge caused by Colletotiichum circinans was found causing a 

 rather serious rotting of the outer scales of white sets in storage in 

 March. As many as five outer scales were involved and there was 

 practically 100 per cent infection in the sets examined. These onions 

 were grown on soil that had been continuously cropped to onions for 

 about ten years. The disease was noted to a limited extent in the 

 fall in Fulton County. Botrytis rot was found to a considerable ex- 

 tent in Fulton County in the fall. Its occurrence in the recently har- 

 vested crop indicates field infection. Black mold {Sterigmatocystis 

 niger) was found abundant in the recently harvested crop in Fulton 

 County in the fall. Harmless infection of pink root, a soil Fusarium 

 disease, was found near Indianapolis on July 12. 



