544 Journal of Agricultural Research voi.xv.No. to 



FUSAEIUM SOLANI 



A species of I^'usarium obtained by Mrs. H. E. Watkins from damped- 

 off western yellow pine in Nebraska was determined by Mr. C. W. Car- 

 penter as F. solani. In a single-pot test on jack pine in autoclaved soil 

 it gave some indication of parasitism, but very much weaker than any 

 of the Pythium debar yanum strains used in the same experiment. In a 

 later experiment (No. 31, Table II) it gave definite indication of a sHght 

 degree of parasitism, both on comparison with the uninoculated controls 

 and with the numerous pots inoculated with species of Phoma, Tricho- 

 thecium, Trichoderma, Chaetomium, nonvirulent Corticium strains, and 

 other fungi, in all of which damping-off was less than half that in the 

 F. solani pots. Though comparison with the other parasites is somewhat 

 uncertain because of the different nutrient substrata used in the inoculum, 

 F. solani appears distinctly less parasitic than the stronger strains of 

 Pythium and Corticium (No. 255, 147) and those of F. moniliforme and 

 F. ventricostim tested, while about equal in effectiveness to a weak 

 Pythium strain and to Rheosporangium aphanidermatus . In experiment 

 60 of Table II heavy inoculation with F. solani resulted in decided 

 germination loss and subsequent damping-off, though less than that 

 indicated for F. moniliforme with the same inoculum. The absence of 

 nutrient substratum in the control pots prevents the experiment being 

 quite as conclusive as it might liave otherwise been. 



In inoculation tests on jack pine and western yellow pine on soil 

 treated with acid and lime, referred to in preceding sections, it failed to 

 affect either germination or subsequent damping-off, while all but the 

 very weakest strains of Corticium caused greatly increased losses, and 

 Pythium debaryanum and Fusarium moniliforme appeared to have moder- 

 ately increased loss. 



The experiments as a whole indicate that the strain of Fusarium solani 

 used in these experiments is a weak parasite on jack pine. Despite the 

 relativel}^ slight virulence of this strain, this species seems worth serious 

 consideration as a damping-off organism, in view of its widespread 

 occurrence. 



OTHER SPECIES OP FUSARIUM 



A preliminary test was made of a mixture of three of Spaulding's cul- 

 tures of Fusarium spp. and three obtained by the writers from pine 

 seedlings at Halsey, Nebr., the latter superficially resembling F. solani in 

 heavy inoculation with rice inoculum on jack pine on autoclaved soil and 

 under moist chamber conditions. Damping-off was negligible. In the 

 first test mentioned under F. solani, another strain of Fusarium resembling 

 it was also tested on a single pot, with less resultant damping-off than in 

 the control pots; three strains of Pythium, debaryanum in the same series 

 all caused heavy and unmistakable increases in damping-off. 



