266 PYTHTUM DE BARYANUM. 



It is somewhat curious that damping off of seedlings has not 

 been more frequently observed in India. The few cases which had 

 previously come under the writer's notice were due to Rhizoctonia. 

 It is possible that this pest of gardens and plant houses in temperate 

 countries is kept in check by climatic conditions in the tropics, 

 since its occurrence at Pusa shows that it is present in soils exposed 

 to as high a temperature as is ordinarily found in the tropics. Its 

 parasitism appears to be as strongly marked here as elsewhere, for 

 not only did it cause germinated cress seedlings to damp off, but it 

 prevented germination in seeds of Ricinus in a manner similar to 

 that recorded by Peters 1 in seeds of beet-root. 



The treatment of damping off is based on the known conditions 

 which predispose seedlings to this disease. These are overcrowding, 

 growth in damp, stuffy localities, excess of water in the soil, excess 

 of organic matter, especially decaying vegetable debris, and use of 

 the same soil over and over again in plant houses and pots. The 

 addition of sand to the soil, so as to improve its texture, frequent 

 stirring of the top soil, exposure to sunlight and fresh air, evenness 

 of temperature, good drainage and frequent change of soil, will 

 generally suffice to keep seedlings in pots and forcing-beds healthy. 

 In open cultivation the disease has not been found to do much 

 damage, except in the case of beet-root, where several other para- 

 sitic fungi aid Pythium de Baryanum in causing the condition 

 known as " wurzelbrand." 



Pusa : 

 January 7th, 1913. 



1 Peters, L. Biol. Anstalt, VIII, 2, 1911, p. 225. 



