THE APPLE SCAB 



29 



by dwarfing and disfiguring the apples that mature. 

 Secretary A. C. Hammond^ of the Illinois State Horti- 

 cultural Society, estimated the annual loss due to this 

 disease in Illinois alone at $400,000, and other authori- 

 ties have estimated it at from one-sixth to one-half of 

 the entire crop. 



The mycelium, or yegetative portion of the scab 

 fungus, consists of brown- 

 ish cells which develop 

 just beneath the skin of 

 the leaf or fruit, but, as a 

 rule, do not penetrate 

 deeply into the tissues. 

 After the fungus has 

 grown in this way for 

 some time it pushes out- 

 w^ard, rupturing the skin ; 

 and on the exposed sur- 

 face short yertical brown 

 threads are developed, on 

 the tips of which the 

 small oval spores are pro- 

 duced (Fig. 14). When 

 mature the spores sepa- 

 rate, and are scattered by wind and rain in all directions. 



Treatment. — In spring, just before the leaf-buds 

 open, spray thoroughly with dilute Bordeaux mixture, 

 or else sj^ray before the leaf-buds begin to swell, with a 

 simple solution of copper sulphate ; repeat the applica- 

 tion of Bordeaux mixture a little later, just before the 

 blossoms open ; spray for the third time just after the 

 blossoms have fallen, adding arsenites for the codling 

 moth if desired ; ten days after this third apj)lication 

 spray again with the combination of Bordeaux mixture 

 and Paris green or London purple. Do not apply Bor- 

 deaux mixture late to early ripening apples. 



FIG. 13. SCABBY APPLE SHOWING 

 EUPTUKES IX THE SKIN. 



