259 



Rust 

 Caused by Pitccinia antirrhini Diet. & Holw. 



Rust is evident on the snapdragon as reddish-brown pustules about 

 the size of a large pin-head upon the leaves. These spots, if numerous, 

 may seriously detract from the appearance of the plant, limit its growth, 

 and check flower production. 



Snapdragon rust is known to occur in Illinois in 7 counties, whose 

 distribution, as shown on Map 126. indicates a very wide range of this 

 disease in the state, with the commonest occurrence probably northward. 



It is controlled in greenhouses by so directing the watering of the 

 flats and benches as to avoid splashing or dropping of the water from 

 leaf to leaf. 



Conclusion 



The preceding pages contain an account of 165 of the plant diseases 

 occurring in Illinois. They attack 44 of our crops and, according to the 

 classification given in Table 41. 115 of them are serious either continu- 

 ously or in years favorable to them while 50 are commonly of less sig- 

 nificance. These are not all the diseases attacking crops in this state, yet 

 the number is large enough to suggest that their presence is a continual 

 menace to successful production and that they are, because of their wide- 

 spread distribution and common occurrence, the cause of a not inconsider- 

 able yearly reduction in the crop yield of the state. 



How great the yearly loss is may be inferred from the estimates 

 summarized in Table 42 from the more detailed estimates previously 

 given. Five diseases of wheat are estimated to have caused a loss aver- 

 aging annually 7.712,800 bushels valued at $11,837,000; two diseases of 

 oats have caused an average annual loss of 12,820,000 bushels valued 

 at $6,47 9,000: and two diseases of corn have caused a similar loss of 

 35,013,000 bushels valued at $24,840,000. Among the fruits, six apple 

 diseases reduce the crop annually by 814,980 bushels valued at $1,240,500 ; 

 one pear disease causes a yearly loss of 22,900 bushels valued at $22,300 ; 

 and one peach disease, a yearly loss of 13.850 bushels valued at $31,220. 

 These 16 diseases attacking 6 of our chief crojjs are responsible for a 

 reduction in yield averaging annually 5(5, 398. 900 bushels valued at $44,- 

 452,000. If it were possible to state in concrete terms the losses resulting 

 from the remaining 99 serious diseases and the damage done by the 50 

 less serious ones, these figures would undoubtedly be multiplied many 

 times; but such a statement would only serve to make more impressive 

 the facts already emphasized — thai many diseases are widely distributed, 

 that most of them are serious, and that the infection of crop plants can 

 result only in costly reductions in yield. 



Losses can be largely avoided by using the a[>i)roved methods of 

 prevention and control which are given briefly in this bulletin for nearly 

 all the important diseases. This is a subject, however, which deserves 



