SCIENCE OF FRUIT-SPRAYING 329 



Mai-nutrition is really the direct cause of the trouble 

 in both cases. In the case of damp, cold soil it arises 

 from insufficient rooting ; there may be a good deal of 

 food in the soil, but there are not enough roots to take 

 it up. In the case of the shallow soil there are probably 

 abundance of fibres, certainly fruit trees often do form 

 thick mats of root in a few inches of poor ground over 

 chalk, gravel or rock ; but there is not enough nutri- 

 ment present for them. 



By draining wet land the soil is dried and warmed to 

 the degree of encouraging root action, when the latent 

 stores of food are eagerly taken up and the tree improves 

 in health. But the remedy in the shallow ground is to 

 rake in a dressing of artificial manure, and also if possible 

 to spread on a coat of rich yard manure, supplemented 

 by soakings of liquid manure as opportunity arises. The 

 mixture of fertilizers recommended in the preceding 

 chapter will be found suitable for the purpose in 

 view. 



Sporadic attacks of canker need not cause the fruit- 

 grower serious anxiety ; a persistent attack need not 

 upset his equanimity if it is concentrated on one or two 

 particular varieties ; but a general attack on most of 

 the kinds should engage his most earnest attention. 



Most fruit-growers find that there are certain varieties 

 which canker badly even where the majority of the sorts 

 are healthy. The varieties are not the same in all cases. 

 Local conditions of soil or climate exercise an influence 

 which is often obscure. Such sorts should not be multi- 

 plied. There are plenty of high-class Apples available 

 that do not canker badly except under direct provoca- 

 tion, and preference should be given to them. 



As the canker question is a very important one to 

 many fruit-growers I will give two tables, showing 



