CHAPTER IV 



DIAGNOSING OF DISEASES 



UST as the physician finds his greatest difficidty- 

 in determining the cause of illness, so the tree 

 doctor, although knowing the diseases to which 

 trees are liable and knowing the remedies, may 

 still find trouble in diagnosing the true cause of the evident 

 abnormal condition. Here it is that experience and judg- 

 ment come in, yet sometimes even an expert remains doubt- 

 ful. Nevertheless, by careful examination, in many cases 

 even the less experienced can determine what ails the tree. 



Usually, if anything is the matter in any living part of the 

 tree, the fohage gives the first indication, and furnishes the 

 most readily available symptoms for diagnosis. 



Hence our examination begins with the foliage, to see 

 whether it shows any divergence from normal conditions 

 in size, quantity, form, or color. With a conception of 

 what the normal foliage ought to be, we ascertain whether 

 the leaves of the individual under examination are smaller 

 than usual, or thinner, whether the foliage as a whole appears 

 slim, whether the leaves are wholly or partially discolored, 

 whether they are mechanically injured, eaten, crumpled, 

 or otherwise misshapen, spotted, wilted, or dead. 



If no local cause, as from fungi or insects, can be ascer- 

 tained as surely responsible, we look next for indications 

 on twigs, branches and bole as accounting for sickly appear- 

 ance of the foliage or death of branchlets. Mechanical 



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