Pomaceous Fruits 



33 



tend only partly around the twigs. Old cankers are very 

 rough, and may extend several centimeters longitudinally 

 along the twig, thus giving it a flattened appearance. 



Pt^^ 



Fig. 10. — Bitter-rot cankers. After U. S. Dept. Agr. 



The fungus causing the rot upon the fruit was described 

 in 1856 by Berkeley. That the cankers are caused by the 

 same fungus was recognized independently by two research 

 parties, Burrill and Blair, and von Schrenk and Spaulding 



