1918.] DISEASES OF PLANTS. 547 



both pruuing and spraying or pruning alone had been carefully done the spread 

 of the disease was effectively checked, but where spraying alone had been done, 

 or where one of these treatments had been carelessly done the bushes were in 

 most cases attacked more severely than usual. The disease was reported from 

 new districts, being now present in nearly every county of Scotland. 



Plant pathology [India], B. J. Butler (Ann. Rpt. Bd. Bci. Advice India, 

 1915-16, pp. 103-113). — Ufra, due to Tylenchus angahus, the most important 

 disease of rice at the pi-esent time, continues to extend itself, practically the 

 whole of the districts of Noakhali, Tippera, and Dacca, and parts of Mymen- 

 singh and probably Sylhet being affected. The loss is very great, especially in 

 some sections where the main crop is deep water paddy. 



The parasite hibernates in the dried stubble, renewing its activity with the 

 coming of the rains. It was found possible to carry the organism in an actively 

 parasitic condition through its normal period of dormancy (December to April) 

 by supplying constantly renewed young rice seedlings and keeping the air 

 moist. This last is thought to be an indispensable condition, probably ex- 

 plaining the comparative immunity of the early crop and of the main crop in its 

 earlier stages. The spring crop, which is, however, of minor importance, may 

 not be liable to injury. The nematode does not appear to survive in the soil, 

 as total destruction of all stubble is followed by a healthy crop. Extensive 

 experimentation is in progress. 



The work of the past two sea.sons has established the view that the parasitic 

 species of Orobanche in Bihar are 0. indica and 0. cernua. 



The work on the black thread disease of Hevea has been continued. Tliis 

 disease, which is active only during the monsoon rains, is not fatal but causes 

 much damage by attacking the tapped ai-ea of the bark. The causal fungus, 

 which is said to differ from Phytophthora faheri, attacks both bark and fruits 

 at points of injury. The disease is favored by excessive humidity and shade. 

 The fruits constitute the chief source of infection. P. parasitica found on 

 Yinca rosea has been studied and germination of the oospores has been accom- 

 plished, the resulting organism corresponding in essentials with P. erythro- 

 septica in Ireland. 



The study of the opium poppy blight has led to the conclusion that while 

 Peronospora arborescens is common and epidemic under favorable conditions, 

 Rhizoctonia develops only under defective drainage conditions. 



Colletotriclium nigrum causes a serious anthracnose of chilli peppers in sev- 

 eral parts of India, the organism penetrating the pod and reaching the seed. 



A plantain vdlt prevalent at Pusa is said to be due to a Fusarium distinct 

 from that causing the Panama disease. In severe cases the rot may reach the 

 stem and kill the whole crown. Attack of the fruit stalk may lead to loss of 

 the whole bunch. The fi'uit rot of plantain due to Glwsporium musarum is 

 controlled by early spraying with Burgundy mixtui-e and repeating this treat- 

 ment every two weeks until the fruit is nearly ripe, when ammoniacal copper 

 carbonate should be employed. 



Polyporvs shorece is the name given to what is considered a new fungus 

 thought to cause a disease of sal trees and described on page 5-55. 



The study of certain wilts of cotton, til, gram, chilli, and other crops has 

 yielded no support to the view that such wilts are due to defective air supply 

 for the roots or to other physical conditions in the soil, a Fusarium appearing 

 to be the causal agent. 



A brief account is given of the chief items of mycological work as carried 

 out by other scientific departments (chiefly the provincial departments of agri- 

 culture), including the palm bud rot operations, a study of tlie black thread 

 disease of Hevea, a disease of paddy {Ephelis oryzce), a root disease of coffee 



