July 10, 1916 



Storage-Rots of Economic Avoids 



559 



The results of these inoculation experiments with F. solani are given 

 in Table II. 



Table II. — Result of the inoculations of Colocasia esculenta {Trinidad), C. esculenta 

 (Manchuria), and Xanthosoma sagitlifoliwm with Fusarium solani 



a Twelve tubers were inoculated with F. solani from Irish potato; all others with F. solani from dasheen. 

 6 None of the checks became infected. 



SCLEROTIUM-ROT 



The sclerotium-rot, while common in the storage heaps where high 

 temperatures and a relatively high humidity prevails, is not so fre- 

 quently met with under all circumstances as rots caused by F. solani 

 and D. tubericola. The causal fungus is known to occur on a num- 

 ber of hosts widely separated in relationship, such as tomato (Lyco- 

 persicon esculentum) , peanut {Arachis hypogaea), cabbage (Brassica 

 oleracea), cotton (Gossypium spp.), violet (Viola spp.), and others. It 

 has been found growing on the dead scales and other debris of many 

 dasheen plants in the field in Florida, but not a single sure case has been 

 found where it invaded the sound tissue. It, like the other fungi so far 

 discussed, is primarily important only as a storage-rot. 



DESCRIPTION OF SCLEROTIUM-ROT 



During a period of three years many tubers and corms have been 

 examined which were somewhat mushy and watery and often covered 

 by numerous almost spherical sclerotial bodies. The watery putrid 

 condition often accompanying this decay is usually the result of sapro- 

 phytic fungi and bacteria which followed the progress of the Sclerotium 

 fungus. If this putrid substance is pared away, a firmer (PI. LXXXI, 

 fig. 3), almost odorless decay will be found from which a pure culture 

 of the causal organism can be plated out. The rotted tissue is ocherous 

 to brown in color, soft but not watery, with a tendency to stringiness. 

 A sharp line characterized by a difference in color separates the healthy 

 from the diseased tissue. The destruction of the tissue is apparently 

 brought about by an enzym secreted by the fungus. At least there is a 

 soft zone ]4,to% inch in width with the charactistic color of the rot from 

 which the organism can not be isolated. 



The hyphae do not enter the cells to any extent, but the tissue finally 

 becomes badly disorganized through the destruction of the middle 

 lamella. 



