Insect and Disease Control 235 



is greatly reduced. Trees that have been properly fumi- 

 gated with hydrocyanic acid gas when received from the 

 nursery should be clean. Another precaution is to wash 

 from the roots the soil that remains on them before the 

 trees are planted, then dip them in a strong tobacco de- 

 coction. 



When young trees are planted without these precautions 

 being taken, or if they become infested later, the soil 

 should be removed for a space of a foot or two about the 

 trunk in such a way as to form a basin, then a pound of 

 fine tobacco dust sprinkled in it and covered. As the 

 rains leach the tobacco and the extract soaks down along 

 the roots, coming in contact with the aphides, they are 

 destroyed. 



As a rule, treatment of the insects on the twigs and foliage 

 is unnecessary, especially if the root forms are effectively 

 controlled. But if serious injury is threatened, spraying 

 with nicotine sulfate at the rate of 1 ounce to 5 gallons of 

 water, or some other tobacco decoction or extract, usually 

 accomplishes the desired result. 



Green peach-aphis (Myzus persicce) 



This insect calls for but passing attention, though in some 

 sections it is rather serious and is more abundant on peaches 

 than any other insect of this group. It is one of the many 

 "plant-lice" having a large number of host plants and is 

 related to the black peach-aphis discussed above. Fre- 

 quently, early in the spring when the shoots and leaves are 

 young and tender, this insect attacks them, and if very nu- 

 merous will cause the blighting of the blossoms and the 

 killing of the ends of the new growlh. 



