SPRAYING PROBLEMS 157 



The method of outbreak and spread of the disease 

 could be studied by systematic observation, deciding 

 beforehand on the localities or actual sites to which 

 special attention should be given. The trial stations 

 and observation sites could be linked together to form 

 a system for England and Wales, which would take 

 into account the most important hill and mountain 

 systems, follow the coast-line and course of the more 

 important river valleys and cross-tracts of land hav- 

 ing any special soil characteristics. Thus in Cornwall 

 attention could be given to the moorlands and inter- 

 vening lowland, to the influence of the sea in the 

 north-western, southern, and south-western aspects, 

 the River Fal and its estuary; in Wales, where detailed 

 rainfall maps have been prepared by the University 

 authorities, the outbreak could be followed in relation 

 to the rainfall; or the epidemic in a county like 

 Montgomeryshire, where the soils are mainly clays, 

 could be compared with the outbreak in Pembroke- 

 shire, where the geological structure is extremely 

 varied. 



Besides bringing home to the general public the 

 advantages of spraying and the necessity of produc- 

 ing untainted crops, the economic advantage to the 

 country would be considerable. Each county, and 

 even district, could form its own spraying time-table, 

 and know within certain limits when and how often 

 to spray and with what strength of solution, and 

 could organize its available sources of labour to the 

 best possible advantage. 



A. S. H. 



