Bean Anthracnose 111 



black spots with colored borders are characteristic of anthracnose. The 

 cankers range in size from a mere speck to spots one centimeter in diameter 

 or even larger. By the union of several large cankers, a broad lesion 

 is often formed which may extend from one end of the pod to the 

 other. A canker may extend through the endocarp and even to the seed, 

 particularly if infection takes place early, in which case the pod sometimes 

 fails to develop and becomes shriveled and dried. Cankers resulting from 

 infections that occurred during the later growth of the pod seldom extend 

 below the endocarp. As the pod matures, the lesion is marked at the edge 

 of a canker by a slightly raised, black ring with a cinnamon-rufous to 

 chestnut-colored border. The center of the spot is then somewhat light 

 buff in color. Flesh-colored spore masses on the surface of a young canker 

 dry down to gray, brown, or even black granulations or to small pimples. 



The appearance of the disease on the pods of the different varieties 

 is very similar. The lesions on Blue Pod Butter, a variety producing 

 dark blue-purple pods, are snuff brown instead of black in color; otherwise 

 they are similar to those on other varieties. On a number of picked pods 

 that had been left in a basket and were somewhat wilted, and in other 

 cases in which inoculations were made, lesions one centimeter or more in 

 diameter appeared which were light brown in color and marked by a 

 slight depression. If the spores had not been present one would hardly 

 have believed the lesions to be anthracnose, particularly as the typical 

 lesions were present also on some of the pods. In some instances these 

 unusual-appearing lesions later assumed the more characteristic appearance. 

 Lochhead (1903) mentions the presence of a pink rot (Cephalothecium 

 roseum) in anthracnose spots on bean pods, and at Ithaca this fungus 

 has been found often in such lesions. 



Blight lesions (Plate VI) on the pods may sometimes be confused 

 with anthracnose. The blight lesion consists of an area having a water- 

 soaked appearance extending along the dorsal suture, or of spots of a 

 similar nature and of various diameters appearing on the sides of a pod. 

 Often a pod may have many such discolored spots, these having originated 

 from insect bites or punctures. The spots usually have an ochraceous- 

 tawny center with a border of a cinnamon-rufous color, and commonly, 

 as the pod matures, the entire lesion turns to hazel or to cinnamon brown 

 with a more highly-colored margin. It may be distinguished from anthrac- 

 nose by the absence of any dark color, 3 by the shape of the lesions which 



•A saprophytic Alternaria may occur on blighted leaves and pods and give a blackened color to the 

 Jesion. 



