Septembek 13, 1907] 



SCIENCE 



347 



DISCUSSION AND CORRESPONDENCE 



THE PARASITISM OF NEOCOSMOSPORA — INFERENCE 

 VERSUS PACT 



In May of last year an article by Howard 

 S. Eeed, now of the Bureau of Soils, United 

 States Department of Agriculture, appeared 

 in Science (page 751), entitled " The Para- 

 sitism of Neocosmospora," this being made 

 up largely out of a bulletin soon after pub- 

 lished by the Experiment Station of Missouri. 

 The article in Science and the bulletin are 

 based on some confessedly incomplete work 

 (bulletin, page 64) done at the University of 

 Missouri with a Pusarium isolated from dis- 

 eased ginseng plants. The contribution in 

 Science is occupied chiefly with a criticism 

 of some of my own conclusions published 

 several years ago in a Department of Agricul- 

 ture bulletin. This tardy reply is due to the 

 fact that I have only recently read the article. 



My first thought was that I must go all 

 over my own work to see how I could have 

 fallen into such an absurd error. On con- 

 sultation, however, with one of my colleagues, 

 who has been much engaged in recent years 

 with diseases of this class, I found he had 

 saved me this labor. Also on a second more 

 careful reading of Dr. Reed's article in Sci- 

 ence, and especially on reading his bulletin, 

 I found so many unwarranted inferences that 

 it seemed hardly worth while to consider his 

 criticisms seriously. However, as his state- 

 ments have entered into literature with the 

 same face value as my own, especially for 

 those who do not look into scientific writings 

 very closely, I am compelled to make this 

 answer. 



I am not specially interested one way or 

 another in the ginseng fungus as such. It 

 may be a weak facultative parasite entering 

 exclusively through wounds made by other 

 fungi, as Dr. Eeed asserts; although nothing 

 in his writings clearly establishes this fact. 

 The points at variance between us will be bet- 

 ter understood if I first summarize the au- 

 thor's actual facts and then his inferences. 



First as to the facts or supposed facts. 



1. He found a Fusarium wilt of ginseng and 

 also an anthracnose of ginseng. He states 



that wilting ginseng plants in all cases were 

 previously attacked by the stem anthracnose, 

 and further that the Fusarium entered the 

 ginseng plants exclusively through stem- 

 wounds made by this anthracnose. 



2. He states further that on inoculating 

 soils with the ginseng fungus, which soils 

 were then planted with watermelon-seeds, he 

 obtained a wilt of the melon-seedlings and 

 found a Fusarium inside the stems (one ex- 

 periment, three pots). Ginseng fungus, per- 

 haps (?). When, however, he sterilized the 

 soil in the autoclave and then inoculated it 

 with his fungus and planted watermelon-seeds 

 in it, the seedlings remained healthy for 

 twelve weeks, although the fungus (ginseng 

 fungus, be it remembered) grew abundantly 

 in the soil. 



3. He sprayed a " thoroughly underdrained " 

 field of ginseng with Bordeaux mixture, and 

 neither disease appeared in it. The Fusarium 

 wilt appeared in a neighboring unsprayed 

 field, which, however, belonged to another 

 man and was not underdrained. From this 

 he concludes that Bordeaux mixture is a 

 remedy for the disease. 



Some of the inferences I think unwarranted 

 are the following: 



1. The ginseng-fungus belongs to the genus 

 N eocosmospora. 



2. This ginseng-fungus and the watermelon- 

 fungus first described by the writer as Fu- 

 sarium niveum are identical. 



3. The watermelon-fungus can enter the 

 plant only when a way has been opened for it 

 by other fungi, e. g., by Thielavia. 



4. Other Fusaria are in the same case. My 

 conclusions, therefore, respecting the para- 

 sitism of the melon-fungus and similar forms 

 for which I made the genus N eocosmospora, 

 are erroneous. 



This sufficiently outlines the points of dif- 

 ference between us. 



Before passing to the manifest inferences, 

 it may be remarked that neither from the 

 article in Science nor from Dr. Eeed's bul- 

 letin can it be concluded with any certainty 

 how his fungus enters the plant (bulletin, 

 page 50), or whether, as he asserts, spraying 



