30 



FUiTGI AKD rCKGICIDES 



Literature. — Articles concerning apple scab may 

 be found in the following publications : Bulletin Ohio 

 Experiment Station, IV, No. 9 ; Report JJ. S. Dept. 

 Agriculture, 1887, pp. 341-347 ; First Eeport Wisconsin 

 Experiment Station, 1884, pp. 45-56; Cornell Univer- 

 sity Experiment Station, Bulletin 48. 



The Powdery Mildew 



Podosphcera oxyacanthce 



About midsummer one may often find on the leayes 

 and young shoots of apple, cherry, quince, j^each, and 



FIG. 14. SECTIOX SHOWIXG SCAB FUXGUS. 



^, spores in position, as developed; B, skin of fruit turned up; C, parenchyma- 

 like cells of the parasite; Z» £>, tissues of the fruit. Much magnified. 



several other trees, small round whitish blotches of mil- 

 dew, which at first have more or less of a radiated ap- 

 pearance, due to the spreading of the threads. In a 

 short time many of the spots enlarge so that they run 



