Dec. 9, 1918 



Seedling Diseases of Conifers 



541 



Table II. — Inoculation with Ftisarium spp. and other fungi on jack pine in autoclaved 



soil — Continued 





60, 1915-- 

 Do.... 



Do..., 

 Do..., 



Do... 



Do... 



Do... 



Nutrient substratum 

 introduced with in- 

 oculum. 



Prune agar and 

 steamed rice. 



None (spore suspen- 

 sion.) 



.do. 



Prune agar 

 steamed rice. 

 None 



and 



.do, 

 .do. 



Location of inoculum. 



Broadcast through- 

 out pot. 

 ....do 



.do. 

 .do. 



(ist 



unit) 



S- 



(2d 



unit) 

 S. 

 5 



(ist 

 unit) 



S- 



2d 

 unit) 



unit) 

 5- 

 All. 



Fungus. 



Fusarium sp. (273). . . 

 do 



do 



F. solani (202) 



Control (a) 



Control (h) 



Control (c) 



Control (a, b, c) 



1- Q 



■0 ti . 

 <" nil? 



The peculiar behavior of Fusarium moniliforme in actually seeming 

 to prevent part of the damping-off in the first two experiments mentioned 

 (the two which are not included in Table II) suggests the possibility that 

 in autoclaved soil under circumstances in which it is not itself able to act 

 as a parasite, it may nevertheless by reason of its vigorous saprophytic 

 growth so occupy the soil as to make it a less favorable medium for the 

 spread of the more virulent parasite or parasites whose presence was 

 indicated by the considerable damping-off in the controls in these experi- 

 ments. That com.petition of saprophytic fungi may limit the damage 

 done by Pythium deharyanum in recently autoclaved soil is indicated by 

 the results of counterinoculation experiments Avhich will soon be pub- 

 lished. Competition between parasites, or between a parasite and a 

 potentially parasitic fungus under conditions which render the latter 

 nonparasitic, is quite probable. In the present case the record of this 

 species of Fusarium in killing other fungi in mixed cultures in agar adds 

 color to the possibility that it may effectively hinder more virulent para- 

 sites in autoclaved soil. 



In experiment 60 it appears that in heavy inoculations with cultures on 

 nutrient substrata F«t5-amtw moniliforme caused germination loss as well as 

 damping-off after the seedlings appeared. This agrees with Spaulding's 

 conclusions {26) . 1 1 is apparently only under exceptionally favorable con- 

 ditions such as very heavy inoculation, or, as in Spaulding's work, 

 unusually deep sowing, that serious germination loss is to be expected 

 from this species of Fusarium. Comparison of the Fusarium pots inocu- 

 lated with F. moniliforme with those inoculated with virulent strains of 



