344 BULLETIN Mo. 189 [June, 



The percentage of infection was about the same with all the carna- 

 tion strains except "Carnation R.O.," which appeared to have lost 

 practically all power of attacking cuttings. This was one of the first 

 strains isolated from carnation. Thus the age of the strain seemed 

 to play an important role in its virulence, and for this reason the date 

 of the original isolation of each strain is included in the table. 



The strains from alternanthera, coleus, salvia, and poinsettia, all 

 cf which were isolated from diseased plants in the same cutting bench, 

 produced in some cases a soft wet ft)t of the carnation cuttings similar 

 to that caused by the carnation strains. In the majority of cases, how- 

 ever, these strains attacked the cuttings at the callus, forming large 

 brown sclerotia which covered the whole callus and so prevented the 

 formation of roots. Brown strands of the mycelium and sclerotia 

 were formed on all parts of the cuttings underground and also be- 

 tween the leaves. Occasionally, small lesions appeared at the leaf 

 bases which were slightly under the surface of the sand. 



The two strains from alternanthera and the one from poinsettia 

 killed about the same number of cuttings as the strains from carna- 

 tion, while the one from coleus caused 100-percent infection and rotted 

 the cuttings off faster than the strains from carnation. The percent- 

 age of infection with the strain from salvia was very low. 



The strain from begonia produced a soft rot somewhat different 

 from that produced by the carnation strains. It appeared on the stem 

 at the surface of the soil and sometimes at the callus. The fungus 

 formed a dense mass of mycelium which completely covered the sand 

 beneath. Here again the virulence was greater than with the carna- 

 tion strains, all the cuttings being killed and in a much shorter time. 



The strains from eggplant, lettuce, and thistle for the most part 

 formed many sclerotia on the stems and in between the leaves of the 

 cuttings, with only an occasional sclerotium at the callus. Small 

 lesions were found to be abundant at the leaf bases and on the stems. 

 These strains were very weak, especially those from lettuce and thistle, 

 which had been in culture for a number of years. 



The cuttings infected with strains from cotton, cauliflower, and 

 sugar cane rotted off at the surface of the soil; the rot started as a 

 lesion at this point and progressed very rapidly until the cutting was 

 killed. Smaller lesions were produced on the stem underground. 

 Sclerotia and the brown strands of the fungus could be found in 

 abundance on the parts below the soil. The strains from cotton and 

 cauliflower were very virulent; all the cuttings inoculated with them 

 were killed one week before the cuttings inoculated with a soil culture 

 of the carnation strains began to die off. 



The potato strains, as a rule, produced a large number of sclerotia 

 and a dark brown mycelium below the soil and on the leaves. The 

 percentage of infection was fairly high and uniform altho the average 

 was below that of the carnation strains. 



