FUNGI IMPERFECTI 



309 



XVII. LEAF SPOT OF BEETS 

 Cercospora Heticola Sacc. 



DUGGAR, B. M. Leaf Spot of the Beet. Cornell Agl. Exp. Sta. Built. 163 : 



352-359- figs.56- 61 - l8 9 8 - 



PAMMEL, L. H. Spot Disease of Beets. Iowa Agl. Exp. Sta. Built. 15 : 238- 

 243. 1891. 



Habitat relations. The beet leaf spot is widely distributed. Both 

 in Europe and America it is a fungus of common occurrence, and 

 it is believed to be more or 

 less prevalent wherever 

 beets are grown even to a 

 limited extent. The red 

 garden beet is seldom 

 wholly free from this 

 fungus, although many 

 varieties are apparently so 

 resistant that the disease 

 is not an important one 

 in garden or truck work. 

 Much damage may be 

 done to sugar beets in 

 any region where summer 

 rains or heavy dews are 

 prevalent. Spanish and 

 Swiss chard are seldom 

 affected to an injurious 

 extent. 



The leaf spots are at 

 first very small brown 

 flecks with reddish-purple 

 borders. As soon as the 

 spots attain a diameter of \ inch or more they become ashen gray 

 at the center, the border remaining as before so long as the blade 

 is green. The spots are distributed over the leaf surface (Fig. 141), 

 and they may become so numerous as to cover a large portion of 

 the surface, yet with no general discoloration of the blade. In 

 time, however, the leaves blacken and dry up gradually from tip 

 to base. As the leaves become parched and dry they stand more 



FIG. 141. LEAF SPOT OF BEETS 



