Al TollASII)I()M\( 1 I ES 479 



of the clover diseases and frequently becomes epidemic in planta- 

 tions of alfalfa, or lucern, a highly important forage ])lant of 

 Central Kurope. In asparagus growing the losses are also 

 sionally severe. 



An ascomycetous fungus occurring upon the stubble of alfalfa, 

 described as Leptospharia circinans Fckl., has been by some re- 

 garded as the perfect stage of Rhizoetonia Mcdicaginis, yet 

 through cultures of ascospores the writer has been unable to pro- 

 duce a mycelium resembling that of the Rhizoetonia. Moreover, 

 the mycelium of the Rhizoetonia has been unusually difficult to 

 propagate in artificial cultures. 



XV. ROOT ROT OF COTTON AM) ALFALFA 

 Ozon'uim omnirontm Shear 



ATKINSON. GEO. F. Method for Obtaining Pure Cultures of Pammel's Fun- 

 gus of Texas Root Rot of Cotton. Bot. (in/. 18 : 16-19. i 



PAMMKL. L. H. Cotton Root Rot. Texas Agl. Exp. Sta. Rept. 2 : 6i-S6. 

 .. ( Also published as Built. 7 : 1-30. iSS^j 



SHKAR. C. L., and MILKS. (',. F. The Control of Texas Root Rot of Cotton. 

 Bur. Plant Ind., U. S. Dept. Agl. Built. 102 (Pt. 5): 39-42. 1907. 



In Texas and other neighboring states a serious root rot of cot- 

 ton ((rossypijim spp.) and alfalfa ^fafici^ii siitirii) has been known 

 for a number of years. It is not, however, confined to these hosts, 

 and among cultivated plants the sweet potato (Ipouura Initattis] is 

 also affected. Pammel in 1 889 reported it on ten or more deciduous 

 trees and also on a few herbaceous weeds. During the summer of 

 1901 I found this fungus on twelve different weeds in a single 

 cotton field near Paris, Texas. Since these hosts represent a 

 number of widely separated orders, it is apparent that the fungus 

 is practically unrestricted. It does not, however, seem to occur 

 upon monocotyledonous plants. 



Little is known about infection and the- progressive stages of 

 the disease. There is apparently very little evidence of the trouble 

 until the plant suddenly wilts and dries up. It would seem that 

 cotton plants are far more commonly killed after some of the bolls 

 begin to mature. Certainly dead stalks become more evident from 

 this time forward. Nevertheless, plants have' been killed by tin- 

 fungus before even any definite llower buds, or squares, have 



