Dec. 9, 1918 Seedling Diseases of Conifers 545 



In experiment 31, Table II, another strain of Fusarium superficially 

 resembling F. solani was tested in heavy inoculation on five pots of jack 

 pine. Damping-off after germination was nearly double that in the 

 uninoculated controls and quite double that in pots inoculated with 

 saprophytic molds on the same substrata. The loss, however, was only 

 two-thirds as much as in the pots inoculated with F. solani, Rheosporan- 

 gimn aphardder mains , and weak Pythium debar yanwm, and much less 

 than in the pots inoculated with the other parasites. The same culture, 

 tested later in the aforementioned experiments on soil treated with acid 

 and lime, gave no indications of parasitism on western yellow pine and 

 little, if any, on jack pine. In all the experiments with this culture the 

 difference between the inoculated pots and the controls was easily within 

 the limits of accidental variation. 



A species of Fusarium obtained from damped-off seedlings of western 

 yellow pine in a greenhouse at Washington, D. C, and identified by Mr. 

 Carpenter as F. acumi'natum E. and E., was tested in experiment 31, 

 Table II, with less subsequent damping-off than in the controls. In the 

 experiment on acid-lime-treated soil it had no apparent effect on yellow 

 pine and on jack pine seemed to increase the amount of damping-off 

 after germination but not more than might be explained on the basis 

 of accidental variation. 



A culture of Fusarium sp. of uncertain identity (No. 273, experiment 60, 

 Table II) gave positive inoculation results in very heavy inoculations 

 only. This culture was recorded in early notes as producing micro- 

 spores in chains, but it was impossible to confirm this in subcultures 

 made some time later. In the experiment this culture appeared not 

 only much less virulent than the F. vionilifor-rne, but even less so than the 

 F. solani culture tested. In view of its doubtful identity and purit)', 

 the results with it are of interest chiefly in its agreement with the results 

 in the pots of F. moniliforme, broadcast inoculation proving more effec- 

 tive than inoculation over limited areas, agar-culture inoculum proving 

 more effective than spore suspensions, and rice inoculum appearing per- 

 haps still more effective, while the very heavy inoculation involved in 

 the use of both media had the maximum effect. 



The conclusion to be drawn from these somewhat fragmentary data 

 is that the strains of Fusarium tnoniliforme and F. ventricosum experi- 

 mented with were above the average of virulence for species of Fusarium 

 on pine seedlings, and that finding a species of Fusarium on damped-off 

 seedlings does not establish as strong a presumption of etiological signifi- 

 cance as would the finding of P. debaryanum or C vagimi. F. solani 

 and F. vasinfectum also appear somewhat parasitic on pine seedlings, 

 and F. acuminatum nonparasitic. Further tests with some of these and 

 other authentically identified species of Fusarium are badly needed to 

 settle the question as to which species are capable of parasitism and 



