Indiana Plant Diseases, 1921 195 



lieved, however, that this collar rot is attributable to the early blight 

 fungus and is identical with the trouble described as foot-rot by Rosen- 

 baum (37) in 1920 and later as collar rot, by Pritchard and Porte (34) 

 in 1921. It is evident that transplants showing these stem lesions should 

 not be set in the fields. 



Leaf mold caused by Cladosporium fulvutn was, as usual, very de- 

 structive in the greenhouse crop and was noted in many houses near 

 Indianapolis on July 12. Observation had led to a supposition that this 

 disease was favored by high temperatures but it was found that the 

 fungus grew well in pure culture between 16° and 25° C and very 

 slowly at 30° and that spores were produced at all temperatures be- 

 tween 9° and 30°, inclusive. Spore germination in water or in prune 

 juice occurred at temperatures from 10° to 35°, inclusive, and very read- 

 ily between 16° and 30° with an optimum for germ tube development at 

 25° C. These temperature ranges are somewhat wider than those re- 

 ported by Makemson (30). The spores are easily detached and carried 

 by air currents since abundant secondary infection occurred in the Petri 

 cultures. 



Anthiacnose of the fruit caused by Gloeosporiian phovioides was 

 somewhat more prevalent than usual in the canning crop and was pres- 

 ent to a serious extent on the sorting belts of factories in Jefferson, 

 Johnson, and Marion counties early in September. It was also noted 

 in the field in Johnson County on Sept. 16. In a variety planting at 

 Lafayette this disease became rather conspicuous on the Yellow Plum 

 variety late in August. In tests with the fungus in pure culture it was 

 found to have no sharp temperature limitations. It grew fairly rapidly 

 at temperatures from 9° to 35° C with somewhat of an optimum at 

 about 27° and a surprising tolerance for temperatures as high as 35°. 

 The oi-iginal source of field infection in the case of this disease remains 

 unknown since foliage infection does not seem to occur. 



In an experimental plot at Lafayette a destructive epidemic of 

 buckeye rot due to Phytophtliora terrestris occurred during September'. 

 The plants were grown in a rather low place and the prevalence and 

 spread of this fungus are attributed to the heavy rains and consequent 

 surface flooding. A high percentage of the fruit became infected. It 

 was evident that wounds were unnecessary for fruit invasion, and that 

 immature fruits were highly susceptible. 



The non-parasitic blossom-end rot occurred to a serious extent in 

 the early market garden crop as noted about Indianapolis on July 12, 

 but was much less destructive in the canning crop than in 1920, due 

 supposedly to the rainy weather of August and SeiJtember. Probably 

 for the same reason the non-parasitic growth-crack trouble was much 

 worse than usual in the canning crop. It was found very severe in 

 September in the stock observed in several canning factories. Cat-face 

 was also present to a limited extent in the canning crop. Sun-scald 

 was rather destructive in the market garden crop during the July drouth 

 and was not necessarily associated with Septoria defoliation. Kendrick 

 noted sun-scald rather prevalent in the canning crop in Grant County 



'' See footnote under eggplant. 



