

1923] 



LEHMAN — POD AND STEM BLIGHT OF SOYBEAN 127 



2. Pycnidia of the soybean fungus are somewhat smaller than 

 those of D. phaseolorum. Harter ('17) finds that pycnidia of 

 D. phaseolorum vary in size from 158 to 475 ;x, averaging 245.48 \i. 

 Measurements of pycnidia of the soybean fungus on stems and 

 pods vary from 82 to 225 X 82 to 375 [x, averaging 162 x 228 fx. 

 Pycnidia of this fungus are regularly greater in one dimension, 

 usually that which coincides with the direction of the scle- 

 renchyma of the cortex of stem or pod. 



3. Pycnospores of the soybean fungus are smaller than those 

 produced by the lima bean parasite. The average size for 

 pycnospores of D. phaseolorum is 7.5 X 3.23 [x as given by Harter, 

 while measurements made by the writer from fresh material on 

 pods collected at Raleigh and Willard, North Carolina, average 

 7.85 X 3.119 [i.. Pycnospores of the soybean fungus on stems of 

 soybean average 6.27 X 2.20 [x; on soybean pods inoculated in 

 moist chamber, 7.15 X 2.29 y.; on lima bean pods inoculated in 

 moist chamber, 6.98 X 2.31 y.; on soybean leaves collected from 

 field, 6.57 X 2.30 fx. Thus it is seen that the pycnospores of the 

 soybean organism are not only shorter but also narrower than 

 those of D. phaseolorum, the average difference amounting to 

 .7 (x in length and 1 [x in width. When one considers the small 

 size of these spores these differences assume considerable value, 

 amounting to approximately 50 per cent of the diameter of the 

 spores of the soybean fungus. This difference persists when the 

 soybean fungus is grown on lima bean pods. 



4. Stylospores are much less frequently found associated 

 with pycnidia of the soybean fungus than with the corresponding 

 stage of D. phaseolorum. Only one of the numerous strains of 

 the former isolated from diseased plants has produced stylo- 

 spores with any degree of regularity, while in the case of the 

 latter, as indicated by the work of Harter, stylospore production 

 may be regarded as the rule rather than the exception on certain 

 media. 



5. Pycnidial formation of the soybean fungus is entirely 

 inhibited by keeping the cultures in total darkness. On the 

 contrary, D. phaseolorum not only forms pycnidia but produces 

 pycnospores also when kept in darkness. 



