Minnesota Plant Diseases. 



327 



Scab of beet. See Potato Scab. 



Anthracnose of currant and gooseberry [Gloeosporium ribis 

 (Lib.) Mont, et Desm.]. This disease is well known in Minne- 

 sota. 'The fungus appears on the upper surface of the leaf in 

 very minute black spots which are cushions of fungus threads. 

 These are formed under the epidermis and then burst through, 

 finally producing spores on the surface of the cushion. _ The 

 fungus is therefore one of the cushion-forming "imperfect" 

 fungi. The spores cling together in gelatinous masses. When 

 the spots are very abundant the leaf turns pale and falls. The 

 whole bush may thus be deprived of its foliage and in conse- 

 quence may be seriously injured. The fruit on such bushes is 

 usLially inferior and the crop for the following year may also be 

 damaged. Treatment with bordeaux has been recommended, 

 as follows : "First spraying with bordeaux before leaves ap- 

 pear, the second as the leaves are unfolding, and repeat at in- 

 tervals of ten to fourteen days until the fruit begins to turn." 

 (Conn. Ex. Sta. Bull. 142 — 1903.) 



Bean anthracnose [CoUetotrichum lindemufhianum (Sacc. et 

 Magn.) Bri. et Cav.]. Beans are very frequently attacked by an- 

 thracnose. The fungus causing this disease is an imperfect 

 fungus belonging to the cushion-forming group. It attacks 

 the pods and also the leaves but is more commonly found on 

 the former. Blackish spots are formed with purplish edges 

 and these spots enlarge, and when abundant may cover a large 

 part of the pod. The tissue under the spot is sunken so that 

 the fungus-thread cushions, which are formed in the center of 

 the spot, are at the bottom of small sunken areas. These cush- 

 ions bear numerous upright threads, from which spores are 

 pinched off, and between these threads arise sterile, sharp- 

 pointed, dark, spine-like threads, which bristle from the top of 

 the cushion in a formidable manner. 



Spraying with bordeaux has been recommended and should 

 commence when the plants are small. They should be made 

 at intervals of a few weeks until the pods are ripening. Damp 

 situations should be avoided and all badly diseased plants 

 should be destroyed. The disease can be carried along 

 with the seed so that it is necessary to avoid seed from infected 

 pods. Care must also be taken to avoid planting beans in badly 

 infected fields. 



