140 



Diseases of Economic Plants 



Scaly-bark ^^^ {Cladosporiimi herbarum Lk. var. dtricolum 

 Faw.). — Small, circular, or oval, rusty-colored spots with 

 well-defined margins, on both bark and fruit, characterize 

 this disease. The bark cracks and forms scales. The spots 

 are at first scattered, but in time coalesce and form large areas 

 upon the branches and trunk, giving it a scaly appearance. 



Fig. 72. — Scaly-bark injury to fruit. After Stevens. 



Similar injury also occurs on the fruit (Fig. 72). Sweet 

 oranges are most affected, the fruit ripening prematurely. 



Top working is recommended, also heading back and 

 painting the trunk and the stumps of the branches with 

 carbolineum and water equal parts. 



Gummosis. — Several diseases recognized by the exuda- 

 tion of gum from the trunks and l)ranches of the trees are 



