THE BEET LEAF-SPOT DISEASE 137 



drical spores projecting outward from tlie breathing 

 pores, or through ruptures in the skin. Each of these 

 spores is divided by transverse partitions into several dis- 

 tinct cells, and each of these cells is capable of sending 

 out a germinating tube to start the disease in a new 

 place. In autumn these spores fall to the ground with 

 the foliage, and remain there over winter in condition to 

 infect a new crop the following spring. 



Treatment. — The last statement in the preceding 

 paragraph indicates the desirability of rotation of crops 

 in preventing this disease. In case the same ground 

 must be used for beets several successive seasons, the 

 leaves should be removed when the crop is gathered, 

 and burned, or composted, and the resulting compost 

 applied to some other crop than beets. If these meas- 

 ures are not sufficiently successful, it is probable that 

 spraying with the common fungicides will prove an effi- 

 cient preventive. 



Literature. — The most important article concern- 

 ing this disease yet published in America occurs in Bul- 

 letin No. 15 of the Iowa Experiment Station. It is by 

 Professor L. H. Pammel. 



