E. J. BUTLER 35 



Phyfcopatbologioal Services. The uowly organised Fieacli service appears t<» 

 be prepared to give certificates for such produce as tubers, roots, and seeds 

 of held crops, though these are outside tlie Convention. If this example is 

 followed we may expect to be able to get certihcates with niost of our imports ; 

 under the present Indian Act we recpiire them for potatoes from certain 

 countries, for sugarcane and for rubber ; and now that Europe is piacticallv 

 committed to the certificate system and the official agency for the puri)ose 

 has been defined, it should not be long before certificates can be obtained, 

 if needed, for most of our imported produce. 



It remains to examine the restrictive clauses of the Convention, to see 

 whether they go further than is justified in the interests of the country. They 

 are chiefly contained in Articles 1 and 5, and deal with the supervision of 

 nurseries, the control of transport and packing, the notification of diseases, 

 the measures to be taken to prevent and check disease, and the grantiufr of 

 certificates after inspection. In all but the last a certain amount of latitude 

 in interpretation is, I think, essential. 



In considering how far the official supervisioir of nurseries and other 

 establishments engaged in trade in living plants should go, a good principle to 

 follow is that adopted at the Rome meeting, namely, that the object should 

 be to facilitate trade while checking the dissemination of disease. A nurserv 

 engaged in the export trade must be kept as free from disease as possible, so 

 that it may fulfil the requirements of the Convention, or of other regulations 

 requiring certificates. To do this it must clearly not lay itself open to infection 

 by continuing to purchase stock from other non-inspected nurseries. It would 

 be best to cease to buy from such nurseries altogether ; failing this, the only 

 other course is to arrange for a very early inspection of the newly purchased 

 stock and meanwhile to keep it as isolated from, the Test of the stock intended 

 for export as possible. It will be readily seen that the latter is not free from 

 risk, as spores from, newly introduced infected plants may easily reach other 

 parts of the nursery through the air or otherwise. For nurseries engaged in 

 internal trade only, the same restrictions are not so necessary. I have several 

 times referred to the generally excellent means which fungi have for 

 continuous spread outside human control, when the distance to be covered 

 is relatively short ; and as the spread by nursery stock within the country is 

 only one of several ways by which the fungus can reach plants within, sav, the 

 same Province, we cannot often hope to do much good by severe restrictions on 

 internal trade. It is difficult to foresee aU cases, but it is fairly certain that 

 the gradual spread of the great majority of diseases of which accurate records 



