01 HEi^OET OF THE AGRlCULTUlUL llESEAUCH 



failed to isolate the species. A leaf disease of Piaiihyen- 

 sis rubber reported from Assam was identified as Cercos- 

 2^0Tu Cearae, which has not previously been recorded on 

 this tree. Diseases of sal, Casuarina, babul pods and deo- 

 dar were also examined for the Forest Department. 



(A) Root-rot caused bi/ Rhizoctonia. — In September of 

 last year a number of crops on the Farm were attacked by 

 a species of Rhizoctonia. The crops damaged were prin- 

 cipally groundnut, cowpea and jute, at the same time speci- 

 mens of cotton seedlings from Cawnpore showed similar 

 symptoms of disease. The fungus was isolated from each 

 host and cross inoculations performed with a view to ascer- 

 taining whether special races of the fungus are restricted 

 to particular hosts and the extent to which crops are liable 

 to infection in the field. Owing to the subsequent dis- 

 covery of Rhizoctonia on the mulberry and papaw, the 

 scope of the work has since become extended; at present, 

 except in the case of the Rhizoctonia on jute, the evidence 

 is against the existence of special physiological races on 

 particular hosts. A fruiting stage of the fungus was dis- 

 covered on the groundnut and coincides with one which has 

 been previously described as occurring on potatoes in 

 America. 



(i) Other flant diseases.— A disease of wheat which 

 does not appear to resemble any hitherto described, was 

 reported from Dharwar and Hoshangabad. It is hoped to 

 investigate it more fully next season. The anthracnose 

 of chillies caused by C oUetotridiun nigruw was widespread 

 last year, and we had several enquiries about it. Other 

 anthracnoses examined were those of beans, sida, mango 

 and plantain. An attack of a species of Phytophthora on 

 rhea was reported from Dacca. The study of the Fhyfoph- 

 thora on castor was continued. The downy mildew of 

 Cucurbitaceae, Plasmofara cubensis, was found at IHisa 

 during the year. This disease, which lias been spreading 

 gradually throughout the temperate portions of the world 

 during the past fifteen years from centres in the United 

 States and Japan, was not previously known in India. 



