F. J. F. SHAW. 137 



In cases where the figures show a wide variation in the nior- 

 tahty the higher number refers to inocuUtions made upon pknts 

 which had been first wounded. 



The variety of ground imt referred to as " small Japan" was ob- 

 tained from Bombay in the hope of getting seed free from infection. 



Preventivk measures. 



Rliizodonia is essentially a soil fungus attacking the subterran- 

 ean portions of plants and passing over unfavourable periods by 

 means of its sclerotia. Any method of treating the disease should 

 have therefore as its first objective the destruction of the sclerotia 

 in the soil. To do this on a large scale is an operation of some diffi- 

 culty and expense, and is not a proceeding which is likely to com- 

 mend itself to the Indian cultivator. Probably the best means of 

 combating the disease is by a careful rotation of crops ; up to the 

 present there does not appear to be any record of Rhizoctonia at- 

 tacking a cereal crop, and such crops might be grown with safety 

 in fields, where more susceptible j^lants would be destroyed. It is 

 not exactly known how long the fungus can perennate in the soil. 

 Prunet (23) mentions three years as the time during which a field 

 might remain infectious. 



In the case of cotton Balls (2) has found a seed-dressing of naph- 

 thaline beneficial in the treatment of the disease. If used in the 

 right proportion the vapour of naphthaline does not injure the ger- 

 mination and is sufficient to kill or inhibit the growth of the fungus 

 during the early stages when the seedling is liable to attack. 



Eriksson's experiments indicated that treatment of the soil 

 with carbolic acid might l)e a preventive for the disease and further 

 work by Salmon (25) has confirmed this. The solution used was 

 I oz. of phenol to 1 gallon of water, and about 40 gallons were applied 

 by means of a watering pot to a plot of land 19 feet by 9 feet. 



Some experiments made in Pusa seem to show that carbolic 

 powder is capable of protecting jute from the attack of Rhizoctonia ; 

 careful research is, however, necessary in order that the germination 

 of the seed may not be injured by the disinfectant — 



