Pomaceous Fruits 



47 



'^Leaf-spots ^^"^'^ (various fungi) (see also black-rot, p. 42). 

 — Aside from the leaf diseases of apple already mentioned, 

 there are numerous other leaf-spots due to various causes. 

 These spots partake of the same general character. That is, 

 they are brown to tan-col- 

 ored, at first circular, later 

 irregularly circular, defi- 

 nitely bordered, and usually 

 concentrically marked. If 

 abundant, or if they enlarge 

 rapidly upon the leaves, 

 they cause their premature 

 fall, and largely defoliate 

 the tree. Such spots pre- 

 vail to greater or less ex- 

 tent in all apple orchards 

 but are most destructive 

 in the Southern states. 

 Numerous species of fungi 

 have been isolated from 

 these spots; some of them 

 undoubtedly sustain a 

 causal relation to the dis- 

 ease. Sheldon claims that 

 in West Virginia much of 

 the apple leaf-spot is due 

 to an Illosporium. 



Whatever the actual 

 causal fungi may be, these 

 spots are all, or nearly all, 

 of fungous origin and are 

 amenable to preventive 

 spraying. The first of three or four applications should be 

 given with the opening of the leaf buds. 



Hypochnose "^' ^'' {Corticium stevensii (Noack) Burt). — 

 Superficially this disease resembles the blight, with which it 

 is hkely to be confounded by the casual observer. It may 



Fig. 21, — Apple leaf-spot in late 

 stage of development, showing 

 concentric rings. Original. 



