DAMPING-OFF IN FOREST NURSERIES. 35 



rated as more strongly parasitic than F . solani, but in a single test 

 only and with a culture of doubtful purity. Fusarium acuminatum 

 E. and E. gave no evidence of parasitism. These results agreed with 

 those of Spaulding (137) in indicating that the ability to attack 

 seedling conifers is not limited to a single species of Fusarium and 

 that F. monttiforme is one of the more virulent. The statement by 

 llartig (61, p. 147-150) that a Fusariumlike fungus was able to cor- 

 rode the young epidermis of pine seedlings has already been men- 

 tioned. 



PYTHIUM DEBARYANUM. 



Pytkium debaryanum Hesse (Artotrogus debaryanum Atkinson, 

 Lucidium pythioides Lohde) has been known since 1874 (74, 86) as 

 a common cause of damping-off of various angiosperms. The first 

 known observation was made by De Bary about 1864 (74) . Despite 

 the large number of hosts on which it has been listed, its parasitism 

 has been definitely established on few. Peters (100) has successfully 

 inoculated sugar beets with pure cultures ; at least part of his strains, 

 including presumably part or all of those he used in inoculation tests, 

 Avere obtained from single spores. Edson (38) working with the 

 same host, reisolated the fungus from inoculated seedlings, and made 

 reinoculations with it. Both find it able to cause root sickness of 

 plants not attacked early enough to be killed outright. Johnson 

 (82) and Knechtel (85) have caused damping-off of tobacco seed- 

 lings with it, and the former reported it also able to persist in the 

 cortex and kill the lower leaves of tobacco plants which survived 

 attack. The fungus has long been reputed parasitic on potato tubers 

 and has now been found by Hawkins (70) to be the chief cause of 

 the rot known as "leak" in California. Peters (99) made success- 

 ful inoculations with pure cultures on cuttings of Pelargonium. 

 Most of the reports of parasitism, however, have been based on 

 microscopic examination or more or less crude inoculation experi- 

 ments. Noteworthy among the latter are those reported by Hesse 

 (74) on Camelina sativa in the original description of the fungus. 

 These were made before pure-culture technique had come into use 

 with fungi, but were so thoroughly checked by microscopic obser- 

 vations at every step in the process that they must be admitted as 

 very good evidence of the parasitism of the fungus. A number of 

 reported angiospermous hosts are listed by Butler (23), Voglino 

 (143), and Johnson (82, p. 34, footnote, and p. 35). Reinking (107) 

 recently reported Canica papaya as attacked. A host which the 

 writer has not found in the literature is rice, found by Dr. Haven 

 Metcalf seriously attacked in the seedling stage in a field in South 

 Carolina. A second apparently new host for the fungus is fenu- 

 greek (Triyonella foenum-graecum). The writer found oospores 

 typical of Pi/thium debaryanum in the tissues of damped-off seed- 



