32 DISSEMINATION OF PARASITIC FUNGI 



to supervise establishments engaged in the trade in living plants, make 

 provision for the notification of disease, and take measures to prevent and 

 combat diseases. A Government which interprets this as an encouragement 

 to any extensive system of official control of the hygiene of nurseries will get 

 little suppoit from experienced plant pathologists. It is generally impossible 

 to standardise remedial measures against any particular disease. The soil, 

 climata, water conditions, and other external circumstances of any locality 

 frequently have a most important bearing on the remedial measures to be 

 applied and the way to apply them. Also the varieties grown, and tho period 

 of the year when the attack develops, differ from place to place. Even in 

 such a well-established treatment as seed disinfection against wheat bunt, 

 there have been cases of failure due to local conditions and varieties grown, 

 in India, Canada and the United States, and the same is likely to be true for 

 certain diseases of nursery stock also. What Government can do is to provide 

 information of the best available kind ; its application to local circumstances 

 requires local knowledge ; and I would be sorry to enter into competition with 

 an experienced and well- in fanned nurseryman in trying to check a disease in 

 a locality of which I did not know the conditions. 



Thus for the first time an attempt has been made to secure genera] recog- 

 nition of the fact that the spread of plant diseases is largely due to human 

 agency. To check this, the Convention goes as far as was perhaps to be 

 expected in a first step. At the same time it is obvious that it does not go 

 far enough to provide complete security, and in one or two respects it does 

 not seem to take sufficient account of the facts regarding the dissemination of 

 parasitic fungi, discussed above. 



The Convention wholly fails to make any distinction between continuous 

 and discontinuous dissemination of parasites. It has been shown that diseases 

 that can make use of the methods of continuous dissemination to cross our 

 frontiers cannot ordinarily be kept out, and there is little advantage in listing 

 them. Fortunately India is not exposed to any appreciable danger from this 

 class of disease. We have already, no doubt, received most diseases of 

 neighbouring countries that could reach us in this manner ; they are probably 

 very few in numbei owing to our geographically isolated position ; and except 

 in the case of diseases newly intioduced into Ceylon, which might spread 

 to South India, or into the Malay Peninsula, which might reach Burma, it is 

 hard to imagine our getting infected from outside in any other way than by 

 means of conveyance on imported plants. To prevent danger from Ceylon and 

 the Malay Peninsula is not easy, especially in such newly introduced crops as 



