Dec. 9, 1918 Seedling Diseases of Conifers 543 



In the series of outdoor inoculations on a Kansas sand lacking humus 

 and treated with sulphuric acid followed by lime, mentioned in the fore- 

 going account of Corticiwm vagum, three strains of Fusarium moniliforme 

 were tested, each being added to 2 plots of jack pine and 2 plots of 

 western 3''ellow pine. The average germination for all 1 2 inoculated plots 

 was only 0.7 that in the 1 6 nearest control plots, and subsequent damping- 

 o£F was slightly greater than in the controls. The net results indicate 

 much less parasitism by F. monilifornie under these conditions than by 

 most of the Corticium strains used in the same experiment, although the 

 species of Fusarium appears nearly or quite as parasitic as the cultures of 

 Pythium debaryanum used. The variation in the controls in the parts of 

 the experiments containing the Fusarium plots was unusually great, and 

 the results less conclusive than those for P. debaryanum. 



The virulence of different strains of Fusarium moniliforme apparently 

 differs (Table II, experiment 31), though the range of variation is less 

 for the four strains worked with than was found to be the case in the 

 larger number of strains of Pythium, debaryanum and Corticium vagum. 

 The weakest strain was more virulent than the weakest strains of these 

 two fungi, but the most virulent strains of F. moniliforme were consider- 

 ably less destructive to jack pine than the most virulent strains of the 

 two better known parasites, at least on the youngest seedlings. No direct 

 compiarison of virulence is possible between three fungi whose different 

 strains vary so decidedly among themselves, unless large numbers of 

 strains of all three from different sources are studied. It seems safe, 

 however, to say that F. mrniUijorme is distinctly less important than 

 P. debaryanum or C. vagum as a parasite on pine seedlings, in view of its 

 apparent infrequence at most nurseries and its failure to cause serious 

 damping-off in inoculation tests, except with very heavy inoculations. 



FUSARIUM VENTRICOSUM 



A species of Fusarium obtained in association with F. moniliforme on 

 an apparently healthy root of western yellow pine was identified by 

 Mr. C. W. Carpenter as F. ventricosum Appel and Wollenw. In inocula- 

 tion on jack pine (Table II, experiment 31) the fungus showed decided 

 evidence of parasitism. Like F. moniliforme, in the same series, it had no 

 marked effect on germinating seed, but caused subsequent damping-off 

 loss more than seven times as great as that which occurred in the unin- 

 oculated pots, and eight times as great as that in pots inoculated with 

 various saprophytic organisms on the same nutrient medium. There 

 seems little question as to its parasitism, though further tests, involving 

 single-spore cultures and reisolation, will be needed for final proof. How 

 frequently it occurs in pine seed beds is not known; it is, however, believed 

 not to be especially common. Its indicated virulence in the test men- 

 tiDned was a little below that of F. moniliforme. 



