339 



Sprnyiiii; for canker is iinictieed ; but do not iiiisniiderstaiKl what is 

 nu-ant. If the organism is established tlien it is lil^ely tliat spraying will 

 not be effective, but trees can l)e protected against infection. It is often 

 stated tliat canlcer is not found in well managed orchards, but this has 

 not been our observation. Even in some of the best cared for orchards 

 we have found the most cankers. In these cases, either the fungus gained 

 entrance to the cambium in only a few instances, or if it did pierce this 

 layer, the limbs w^ere cut off just back of the diseased area and a new 

 slioot allowed to form. 



It has been noticed for a number of years that not all varieties are 

 attacked. We have in mind an orchard in which three rows were the 

 Twenty Ounce variety. Other varieties on either side were unaffected. 

 Just why this difference? Is it due to the virulence of the fungus or does 

 it depend uixm increased susceptibility of the host, this in tui'n to be at- 

 tributed to some subtle clumge in nutrition, soil condition, or some other 

 overlooked factors of environment? Soil conditions were apparently uni- 

 form, so that some more remote factor nuist have contributed to this 

 phenomenon. 



Is it possible to inject Into a tree a substance which would render it 

 imnume? It is claimed by some that such a thing is possible. After all, 

 then, just how far is the canker fungus res])onsible for the destruction of 

 the host? May not its invasion be the result of changes from some of the 

 causes suggested rather than the direct work of the parasite? The ques- 

 tions are only to he answered by hoping that future investigation will reveal 

 some of these remote, yet interesting, questions to such an extent that 

 economic conditions generally will be benefited. 

 TTfl&ff.s/i CoUeye, 

 Vrairfor(]s:riUc. Ind.. June 1911. 



