694 INSECTS AFFECTING VEGETATION 



the leaves, that it is also to be found upon the bracts and peduncles 

 of the flowers, and even upon the seed pods themselves. For this 

 reason he thinks that the disease may be transmitted through the 

 seed so as to be in readiness to affect young seedlings. Treatment 

 of this disease, and a successful remedy seems to be at hand in the 

 well-known Bordeaux mixture. Numerous fungicides were experi- 

 mented upon, but the Bordeaux mixture has proved most efficient. 



There is every reason to believe that by beginning the spray- 

 ings early the leaf-spot may be almost entirely prevented by the 

 use of this fungicide. If the disease continues so disastrous as it 

 was in certain sections during the past season, for success growers 

 must expect to spray their beets with the same regularity as has been 

 found necessary in growing potatoes. 



In general, even the strong solutions of copper sulfate gave 

 slightly better results than the water; and germination was often 

 slightly hastened. In a preliminary test, the germination was 

 very markedly in favor of the copper treated seed; but since the 

 conditions were abnormally close and moist, the exclusion of bac- 

 teria by the copper solution might have caused the apparently ex- 

 cessive benefit. 



It remains to be determined, however, if it is desirable to treat 

 the seed for the prevention of the leaf-spot. (Cornell E. S. B. 163.) 



Beet Scab. The smooth surface of the beet root may often be 

 disfigured by warty or scabby excrescences. The texture of these 

 injuries is somewhat corky or spongy, and the larger diseased 

 areas will show that the injury is not entirely superficial, but to 

 some extent alters the tissues immediately underlying such areas. 

 The disease begins as small irregularities either widely scattered 

 or clustered. Individual ones spread in extent, and groups often 

 become united, so that in time it may spread over large areas, or 

 small isolated areas may remain. One often notices a tendency 

 for the scabby spots to be arranged in more or less definite bands, 

 often just at the surface of the ground. The diseased bands, or 

 areas, may, however, appear much lower. It is very probable that 

 this is determined by soil and moisture conditions. The scabby 



Erotuberances are abnormal developments of corky tissue stimu- 

 ited to excessive growth by the presence of the fungus. Professor 

 Arthur has noted sunken scabby spots on the surface of the beet, 

 and he explains these as early injuries which failed to develop 

 further, when the conditions were probably unfavorable, and future 

 growth of the beet has left them rather as pits than as excrescences. 

 In 1890 Professor Thaxter discovered that potato scab is 

 caused by the growth on the surface of the tuber of a fungus which 

 he named Oospora scabies. When scabby potatoes are placed in a 

 moist chamber, a light, grayish, mould-like growth of the fungus 

 may appear on the surface ; and it was by inoculations with pure cul- 

 tures of this fungus that he was able to reproduce the disease on 

 healthy tubers. 



In 1891 Professor Bolley found the scab of beets abundantly, 

 and the microscopic evidence which he obtained indicated that 



