REMEDIES FOR PLANT LICE ON CITRUS TREES 



Though it is seldom necessary to employ artificial means in dealing with these 

 insects, yet any of the forms described may almost entirclj' overrun young trees. 

 I know of such a case at Claremont in the year 1909, where a young Valencia 

 orange orchard was badly infested and nearly all of the new growth killed back 

 as fast at it grew out. But even greater damage may be done to young buds 

 placed in old trees. On these tender shoots the green louse, Macrosiphum citri- 

 folii Ashm., is especially bad, and in such cases should be controlled by sprays. 



In using sprays for these aphids, we must first take into consideration the 

 tree and what it can stand. Though the citrus trees are evergreen and do not 

 admit of severe winter sprayings, as do the dormant deciduous trees, yet the 

 leaves are more resistant than are the tender leaves of the latter, and will stand 

 more summer spraying, when it is most necessary for the insects under discussion. 

 So far I have never found any of the aphids depositing eggs to bridge over the 

 winter months. Adult insects, however, may be found in limited numbers through- 

 out the entire year in Southern California, so we do not have to deal with a distinct 

 egg-laying stage, which is difficult to handle except with very strong sprays. 

 Neither do we have to deal with root forms, like the underground forms of the Black 

 Peach Aphis {Aphis persicae-niger Smith) and the Woolly Aphis of the Apple 

 {Schizo7ieura lanigera Haus). 



The sprays recommended, then, are such as might be used on citrus trees and 

 are not intended as remedies for aphids on all trees and plants, though many of 

 them are standards and need but little additions of water to serve any purpose. 



Spray Formulae 



TOBACCO SPRAYS 



Tobacco Decoctions 



(1). Tobacco stems, dust or waste 2 pounds. 



Water 4 gallons. 



(2). Tobacco leaf 1 pound. 



Water 4 gallons. 



Steep the tobacco in the water for one hour and apply in two applications of 

 five days apart. 



Commercial Tobacco Sprays 



(1). Black Leaf Extract 1 gallon. 



Water 30 gallons. 



(2). "Black Leaf 40" 1 gallon. 



Water 1000 gallons. 



By adding one pound of soap to every fifty gallons of these sprays the 

 eflSciency is greatly increased. 



Tobacco Decoction and Soap 



Tobacco leaves or waste 1 pound. 



Water 6 gallons. 



Soap 1 pound. 



Dissolve the soap in the water and steep the tobacco in this solution for 

 one hour. 



