36 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 



lings received by Prof. William T. Home, from Sonoma County, 

 Calif., with the statement that the disease was seriously affecting 

 the stand. The fungus was easily isolated, and the results of suc- 

 cessful inoculations on pine with the cultures obtained are included 

 in Table V (p. 47). A fungus resembling P. debaryanum was 

 also found in damped-off cowpea (Vigna sp.) seedlings grown in 

 rotation with pines at a Nebraska nursery. 



Pythium equiseti Sadebeck, reported as parastic on the prothallia 

 of E guise turn arvense, was successfully used by Sadebeck (117) in 

 crude cross-inoculations direct from E. arvense to potato tubers. 

 De Bary (5) reversed the direction of the experiment between 

 cryptogamous and phanerogamous hosts by successfully inoculating 

 prothallia of Equisetum arvense with Pythium del>aryanum directly 

 from diseased Lepidium seedlings. He also secured positive results 

 on prothallia of the fern Todea africana by the same method. The 

 Equisetum prothallia he found to be especially favorable media on 

 which to develop Pythium debaryanum*. Fischer considers the 

 fungus found by Bruchmann (17) and Goebel (49) on prothallia of 

 Lycopodium sp. as probably identical with P. debaryanum. A care- 

 ful reading of the original articles is sufficient to show that the sym- 

 biotic fungus which they described was an entirely different or- 

 ganism. Saprolegnia schachtii and Sporodospora jungermanniae^ re- 

 ported on two of the Hepaticse, are of doubtful position (42, p. 403), 

 though Butler (23, p. 89), after a survey of the literature, apparently 

 favors the view that the former is distinct from the damping-off 

 fungus. De Bary (5) reported Vaucheria and Spirogyra apparently 

 immune against P. debaryanum. 



Early references to Pythium denary anum in connection with 

 gynosperms seem to have been based on the probability that it 

 would be found to be the cause of damping-off in conifers (6 ; 97 ; 134, 

 p. 27). The first actual finding of the fungus in any gymnosperms 

 of which the writer is aware is indicated by a label marked Pythium 

 debaryanum in the handwriting of Mrs. Flora W. Patterson on a 

 package of coniferous seedlings from a New York nursery collected 

 in 1904. 4 The seedlings, judging from the several rather long cotyle- 

 dons and the fact that both cotyledons and primary leaves are denticu- 

 late, are probably of one of the species of Pinus having medium-sized 

 seed. In 1908 Dr. R. J. Pool, of the University of Nebraska, and his 

 student, Mr. H. S. Stevenson, obtained in culture from damped-off 

 coniferous seedlings a nonseptate fungus which was probably 

 Pythium debaryanum, but which formed no distinctive spores on the 

 media on which it was grown. A year later the writer obtained the 

 fungus from pine seedlings at the same nursery and reported it as 



4 In the Office of Pathological Collections, Unitea States Bureau of Plant Industry. 



