532 Journal of Agricultural Research voi. xv,no.^o 



ment, remained free from disease. With the last two hosts the controls 

 received sterile agar. 



In five additional experiments inoculum was distributed broadcast over 

 the entire pot. In three of these, cultures on corn-meal mush were used 

 as inoculum, and most of the germinating seed of jack and western yellow 

 pine, and Douglas fir, respectively, v/ere killed before they were able 

 to break through the soil. The total number of seedlings involved in 

 the experiment with Douglas fir was small. Though the controls were 

 treated with sterile corn-meal mush and though the fungus was found 

 in the killed seedlings in the inoculated flat, repetition is considered de- 

 sirable for this host. In the two other experiments positive results were 

 secured with both of the pines, with agar cultures as inoculum. 



In five other experiments positive results were obtained with these 

 pines by inoculating them with agar cultures at only one or two points 

 in each pot and in one of them very definite results were also secured 

 with white pine. In two of these experiments on jack pine, inoculation 

 with single sclerotia in each pot was tried without the addition of any 

 of the nutrient substratum with entire success. In the experiments with 

 sclerotial inoculation and in the test on white pine the controls remained 

 entirely free from disease. In the other experiments mentioned in this 

 paragraph more or less accidental infection took place in the controls; 

 positive results consisted in less germination and more subsequent 

 damping-off in the treated plots than in the controls. In the inoculations 

 mentioned in this and the preceding paragraphs the number of pots 

 inoculated with Corticium vagum varied from a single lo-inch flat in 

 the smallest experiment to 178 3-inch pots in the largest; the controls 

 from a single flat to 30 pots. 



In only two experiments Corticium vagum failed to give positive re- 

 sults. The loss was heavier in the inoculated pots than in the controls 

 in both cases, but the difference was so slight as to be negligible. Both 

 of these experiments involved inoculation at two points only in each pot. 



These inoculations have the effect of confirming the field evidence of 

 the parasitism of Corticium vagum on four pines, jack, red, white, and 

 western yellow, and somewhat less positively on Douglas fir. Its appar- 

 ent success on all of the coniferous hosts tested justifies the prediction 

 that under favorable conditions it is likely to be found to be one of the 

 causes of damping-off of most or all of the coniferous species which com- 

 monly suffer from this disease. Only part of the strains are vigorously 

 parasitic on conifers, some strains, even though isolated from conifers, 

 failing in repeated inoculation tests under favorable conditions to pro- 

 duce any considerable amount of disease. 



