family and of the genus Primus are immune. The tubers 

 of the sweet potato are susceptible to attacks from the 

 fungus. 



Ozonium consists of sterile mycelium belonging in most 

 cases to the genus Coprimes. 



The fungus is especially active in waterlogged soils and 

 such as are feebly aerated. A deeper tillage is often 

 advantageous in diminishing attacks from the pest, and a 

 rotation of crops of from two to three years duration, in 

 which members of the grass family are employed, is a 

 good means of keeping the pest in check. 



MaSSEE : Text Book of PL Dis., p. 346, 1907. 



Bull. No. 7, Texas Agric. Exp. Station. 



Shear and Miles : U.S.A. Dep. Agric., Bureau of 

 Plant Industry, Bull. No. 102, Part V. 



Ozonium sp. has been shown to cause a root disease of 

 Para rubber in Brazil. 



SCLEROTIUM SP. 

 (Leaf Blight of Coffee.) 



Has been reported from Porto Rico. The fungus appears 

 to attack the root system first and then to ascend the stem 

 by means of brown or black strands ; when these strands 

 reach a leaf they spread and form a cobweb-like structure. 

 The leaf dies, but remains attached to the stem by a 

 thread of mycelium. 



The genus Sclerotiiun was founded a long time ago for 

 fungi which possessed masses of hyphae, usually of more 

 or less definite form, constituting bodies (sclerotia) which 

 are intended for reproduction. The members of the genus 

 Sclerotium have in many cases resolved themselves into 

 species of the genus Sclerotinia. 



Porto Rico Agric. Exp. Station Report, p. 399, 1904 



APPENDIX. 



A. Diseases due to Physiological Causes. 



MOSAIC DISEASE OF COTTON. 



The symptoms of the disease are the withering, 

 blackening and premature death of the leaves of the plant. 



59 



