A SCLEKOTIAL DISKASK OF RICE. 



BY 



F. J. F, SHAW, n.sc. (Lond.), a.r.cs, f.l.s. 



Recent investigations in plant pathology have shown that 

 a not inconsiderable number of the diseases of plants are to be 

 attributed to the ravages of sclerotial fungi. Considerino- the 

 habitat of these parasites it is not surprising to find that tuberous 

 crops {e.g., potato, carrot, beetroot) seem peculiarly liable to 

 attack, the disease in such cases being usually known as " root 

 rot." In other cases, however, the host plant is attacked in the 

 seedling stage, the symptoms closely simulating the " dampino- 

 off" due to Pythium and its allies. Of sclerotial funo-i, which 

 cause such diseases, one of the best known is Rhizoctonia, to 

 which the " root rot " of many tubers, as well as the " dampino- 

 off" of certain seedlings, is to be attributed. There has, however, 

 recently been detected in India a disease of rice, due to the 

 attack of a sclerotial fungus, which seems to present some distinc- 

 tive feature in its effects upon the host plant. 



The fungus is known as Sclerotnim Oryzcp, Catt., and was 

 first described by Cattaneo (2), in 1879, as the cause of extensive 

 damage to the rice crop in Novara and Lombardy. His descrip- 

 tion was restricted to the morphology of the fungus on the rice 

 plant and the symptoms of disease in the crop : as, however, cul- 

 ture work and inoculations were not attempted, adequate proof of 

 the parasitic nature of the fungus was not obtained. Since the 

 work of Cattaneo the fungus has also been discovered in Japan by 

 Miyake(7), and has, within the past year, been collected in 

 India, 



