1916] 



PARASITIC RHIZOCTONIAS IN AMERICA 



347 



EXPERIMENT 3: INOCULATION OF OLD CARNATION PLANTS IN POTS 

 WITH VARIOUS STRAINS OF RHIZOCTONIA 



The resistance of young rooted carnation plants to the various 

 strains of Rhizoctonia other than those from carnation was very 

 marked in Experiments 2 and 2a. To determine whether or not old 

 carnation plants were even more resistant, the following experiment 

 was carried out, involving 90 plants and 18 strains. 



Carnation plants (White Enchantress and White Perfection) 

 were brought in from the field and planted in pots, which were then 

 placed in the bench. The plants were grown under the best possible 

 cultural conditions and on November 27, 1912, when they had become 

 firmly established, they were inoculated. Five plants of the same size 

 were used for each test, one being left as a check. The other four were 

 inoculated by placing a bit of infected green-bean plug near the stem 

 about one-half inch below the surface of the ground. The stems of 

 two plants of each test were slightly wounded before the plugs were 

 placed by them. Observations were discontinued on March 27, four 

 months later. The results are presented in Table 5. 



Only two plants inoculated by contact died during the course of 

 the experiment, and both were killed by carnation strains. However, 

 where the- stem was slit, the various strains were in most cases able to 

 infect and kill the plant. The check plants remained healthy during 

 the experiment. 



TABLE 5. SUSCEPTIBILITY OF OLD CARNATION PLANTS (IN POTS) TO VARIOUS 

 STRAINS OF RHIZOCTONIA: EXPERIMENT 3 



