INJURY RESULTING TO SCALE-INFESTED TREES. 



15 



to the fruit, as does also the red scale, resulting in expense for the 

 cleaning of fruit or rendering it of a lower grade and, in extreme 

 cases, entirely valueless. 



The black scale, although a much larger insect than either the red 

 scale or purple scale, appears to have, generally, little effect on the 

 vitality of the tree. Trees severely infested with the black scale may 

 appear as healthy as neighboring trees which are clean. Branches 

 are seldom if ever destroyed by its attacks alone. 



The commercial importance of the black scale arises largely from 

 its habit of secreting honeydew, which spreads over the leaves, fruit, 



Fig. 7.— Orange tree showing branches at center partly destroyed and stripped of leaves by purple 

 scale {Lepidosaphes beckii). (Original.) 



and branches, furnishing a growing medium for a black or sooty-mold 

 fungus, resulting in a black coating throughout the tree. This 

 coating is removed from the fruit by washing, or in light attacks by 

 brushing. In the investigation by Mr. G. Harold Powell'* of the 

 causes of decay of oranges while in transit from California, it was 

 shown that the decay was greater in washed than in unwashed fruit. 

 To avoid the washing of fruit it is necessary to destroy the scale in 

 the orchards. 



a Bui. 123, Bur. Plant Industry, U. S. Dept. of Agriculture, 1908. 



