50 



NEBRASKA STATE HORTICULTURAL SOCIETY. 



The observations recorded in this bulletin are mainly the re- 

 sults of tests of spra.ving"as a preventive of the diseases under 

 consideration. The tests of spraying: against apple scab can 

 hardly be said to be experimental. They are more in the nature of 

 demonstrations. Although spraying for apple scab is in reality 

 beyond the experimental stage, tests of the sort reported here 

 are of considerable value, since Nebraska fruit growers and 

 farmers have not been uniformly successful in their attemps to 

 hold scab in check by spraying. As regards cedar rust, the 

 work is largely experimental, comparatively few attemps having 

 been made before to control it by spraying. 



HOW THE DISEASES WORK. 



Before passing to the consideration of the spraying tests, it 

 is well to understand something of what the diseases are and 

 how they work. Description of the fungi concerned and detail- 

 ed accounts of their life histories are rather for the plant path- 

 ologist to undertake than for the horticulturist. Nothing of the 

 sort will therefore be attempted in this account. 



Fig. 1 Leaves of Rails Genet apple showing apple scab. 



