102 THE AMERICAN APPLE ORCHARD 



than the hnie-sulphur mixture. There is a slight dis- 

 advantage also in the fact that they do not show on 

 the tree as the hme-sulphur spray does. It is much 

 harder therefore to determine when a tree is perfectly 

 sprayed. If windy weather necessitates several turns 

 on each row this difficulty becomes really serious. 



At the present moment there are being introduced 

 by various experiment stations certain formulas for 

 the home preparation of oil sprays. Enough experi- 

 ence has already been gained to show that these will 

 probably equal the proprietary brands of soluble oil 

 in efficiency when properly prepared. Beyond this we 

 can add only that tiiey have the same advantages and 

 the same disadvantages (except as to cost) as the 

 proprietary articles. 



In a general way it seems that these oil sprays prove 

 more satisfactory in the southern states and less so in 

 northern orchards. 



Various formulas have been recommended for self- 

 boiling lime-sulphur washes, but while they have some- 

 times been successful they cannot be generally recom- 

 mended at present. There have also been put on the 

 market several proprietary insecticides for use against 

 the San Jose scale. Most of these are pure fakes, and 

 none of them seems to be really worth while. 



Leaf-Eating Caterpillars — There are several spe- 

 cies of insects which feed on the leaves of apple trees. 

 A few of these sometimes become sufficiently numer- 

 ous to cause serious damage. The two most common 

 ones are the tent caterpillar and the fall web worm. 

 Occasionally there are outbreaks of the forest tent 

 caterpillar or other insects which do very great dam- 

 age, but in most years the injury to foliage by insects 

 is only moderate in extent and is confined to a few 



