296 The Principles of Fruit-growing 



ing a foot or so above the ground. Coal-tar is used with 

 safety. Soap and carbolic washes in early summer are 

 effective against the flat-headed borer (this borer is likely 

 to work on the sun-scalded or injured parts of the trunk 

 and larger limbs) ; probably if the trunks are well drenched 

 with the lime-sulfur spray, the injury will be lessened. 

 The use of axle-grease is not advisable. It is possible that 

 no injury would result, but on the other hand if the grease 

 should contain any of the oils, which soak into the trunk, 

 or any turpentine, it might kill the trees. The addition 

 of sulfur will do no harm, and also no good. 



In short-generation plants, as the small-fruits, rotation 

 of plantations is a very important means of circumventing 

 borers and some other pests. This is specially true of the 

 strawberry, in preventing depredations of the root-borer, 

 root-louse and white grub. Short, sharp rotations, clean 

 tillage, burning of rubbish about the plantation, vigorous 

 plants, are very effective means of getting ahead of many 

 pests. 



Cankers and bad spots; wounds. 



Rough and sunken places in the bark on apple trees 

 may be cankers, produced by a parasitic fungus (the canker 

 of the peach is produced by the same fungus that causes 

 the fruit-rot) ; smooth, dead, more or less sunken spots on 

 apples, pears and quinces may be due to pear-blight. 

 There are other kinds of bad spots in the bark, the cause 

 perhaps unknown. In some cases they may be due to the 

 work of the flat-headed borer or to sun-scald (page 292) . 



The treatment of cankers is described as follows by 

 Jehle (Cornell Circ. 26) : "Whatever the origin of cankers, 

 their treatment is essentially the same except that in the 

 case of an infectious disease, such as the brown-rot canker, 



