10 STATE HORTICULTURAL COMMISSION. 



exercised, for if applied in too great quantity there is danger 

 of killing the tree. One or two shovelfuls can be used on an 

 old tree, but a young tree should not be treated with this 

 substance. 



The use of tobacco dust has given good results, particularly 

 on young trees and nursery stock. The application should be 

 made in the fall of the year, so that the rains can leach out the 

 tobacco juice and bring it in contact with the aphids. 



For the branch, or aerial, form a good kerosene emulsion 

 or whale-oil soap wash (summer formula) will soon reduce 

 the pest. 



KEROSENE EMULSION. 



Coal oil (150 test) 4 gallons. 



Laundry soap 1 pound. 



Water . 2 gallons. 



Dissolve the soap by boiling in the water, and when dissolved 

 and while boiling pour with a dash into the kerosene. Churn 

 the mixture for ten or fifteen minutes, either by pouring back 

 and forth from one vessel to another, or by pumping the liquid 

 back upon itself. The emulsion should have the consistency 

 of cream. 



For a winter wash when trees are dormant, use one gallon of 

 emulsion to six gallons of hot water. 



For a summer wash use one gallon of emulsion to ten gallons 

 of hot water. 



Prune Aphis (Aphis prunifolias) . These insects are readily 

 recognized by their bluish-green color 

 and by the abundance of honey-dew 

 generally found on the ground under 

 the infested trees. In abnormal ,sea- 

 sons only does this pest become inju- 

 rious to the prune trees. Our native 

 lady-birds and syrphus flies generally 

 keep this species under control, but 

 in the absence of these friends use the 

 summer formula of the kerosene 



FIG. 5. Prune Aphis (Aphis emulsion or the whale-oil soap solu- 



prunifolise), 



tion. 



Black Peach Aphis (Aphis persicte-niger). This insect is 

 one of the most dangerous foes of the peach tree, and the 

 grower should, at the very start, wherever he notices its 



