Pomaceous Fruits 



39 



bordered with a narrow red line. In older cankers the 

 diseased bark becomes cracked, furrowed, and much rough- 

 ened. 



On the leaf this fungus causes small, regular, light brown, 

 yellowish, or whitish spots, 

 usually 1-2 mm. in diameter, 

 each of which may bear one 

 or several pycnidia. 



The Ben Davis, Missouri 

 Pippin, Limber Twig, and 

 Maiden Blush are highly sus- 

 ceptible, while Winesap, Jona- 

 than, and York Imperial are 

 almost immune. 



Ordinarily three applica- 

 tions of 3-4-50 Bordeaux 

 mixture suffice to control 

 blotch. The first spraying 

 should be made two or three 

 weeks after the petals have 

 fallen; the second about two 

 weeks later; the third two 

 weeks thereafter. Lime-sulfur 

 should be substituted during 

 wet weather to avoid Bor- 

 deaux injury. Careful prun- 

 ing to remove affected twigs 

 is beneficial. 



QRusts ^^' ^^' ^^^ {Gijmnospor- 

 angium sps., Rcestelia). — 

 Rusts of the apple may usually 

 be recognized by their char- 

 acteristic spots on the leaf, or more rarely upon the fruit or 

 twig. These spots, yellowish green at first, gradually become 

 darker, approaching orange. Upon close examination, the 

 upper surface of one of these discolored spots is seen to con- 

 tain numerous pustules, at first honey yellow, finally black, 



Fig. 15. — Apple leaf affected 

 with rust. After Anderson. 



