Dec.9. i9i8 Seedling Diseases of Conifers 537 



subsequent damping-off. The soil used was a greenhouse mixture of 

 sand and loam. 



FUSARIUM SPP. 



Species of Fusarium and Fusoma have been frequently reported as 

 being the cause of damping-off of conifers in Europe. The first crude 

 inoculations were made by Hartig (12), who produced typical damping-off 

 by placing healthy seedlings in contact with plants which had damped-off 

 and were bearing spores of Fusarium spp. Von Tubeuf (27) reports 

 having inoculated pine seedlings with artificial cultures, but in so small 

 ail experiment and with so little in the way of positive results as to be 

 inconclusive. He later (27) states that he and Hartig have repeatedly 

 caused the death of plants of European conifers by inoculating them with 

 Fusarium parasiticum, "also from pure cultures." No detailed report of 

 pure-culture inoculation experiments has been furnished in the European 

 literature noted, and the ability of the Fusarium or Fusoma strains, 

 which have been variously mentioned under the specific names of pini, 

 parasiiicutn, and hlasiicola to cause damping-off in Europe has rested 

 mainly on the frequency with which they have been obtained from 

 damped-off conifers. The strains which have been found on conifers and 

 which have been used in inoculation are not sufficiently well described to 

 make it possible to connect them with any of the species at present recog- 

 nized. There is furthermore no way of telling whether the different 

 reports of species of Fusarium and Fusoma on coniferous seedlings refer 

 to the same or different organisms. 



In America Spaulding (25) reports briefly inoculation experiments with 

 a number of different strains of Fusarium the detailed record of which 

 the writers have been permitted to examine. Sufficient damping-off 

 occurred in some of the control plots, so that it does not seem possible to 

 say for any one of the strains he used that its parasitism vvas proved, in 

 view of the fact that each strain was used in a single pot only. For the 

 strains in general, his work established beyond reasonable doubt that at 

 least some of them were parasitic, the loss in the pots inoculated with 

 Fusarium spp. as a whole averaging well above that in the controls. 

 Among the species for which parasitism was indicated quite strongly 

 are F. vasinfectum E. F. Smith and F. vwniliforme Sheldon. The 

 evidence is especially strong for the latter species. F. vasinfectum from 

 cotton gave apparently more positive results than the strain from water- 

 melon. The general conclusion from his experiment seems to be that a 

 number of different strains or species of Fusarium are probably able to 

 attack pine seedlings under the very favorable inoculation conditions 

 which he furnished, and that F. m^niliforme iS one of the more virulent. 



Prof. P. S. Lovejoy, working as a student under the direction of Dr. J. B. 

 Pollock in 1907, two years after Spaulding did his work, produced damp- 

 ing-off in western yellow pine with a species of Fusarium isolated from 

 88094°— 19 2 



