248 NEBRASKA STATE HORTICULTURAL SOCIETY. 



vSCAB. 



Cause: The disease is caused by one of the fung^i ( Ventnria 

 vhlorosporo). The fungus is regularly branched and creeps in 

 every direction from the place of infection. It is a superficial 

 fungus. 



Description: The disease shows first in the spring by the 

 appearance of velvety dark green spots on the leaves. It is 

 sometimes called mildew or leaf blight. When the disease is 

 at its worst the leaves may curl up or fall off. Mr. Longyear 

 of the Michigan Station says that the fungus may attack the 

 stem at blossoming time and cause the fruit to drop. The 

 fungus also attacks the fruit causing spots which at first 

 resemble those on the leaves. The fungus works just under the 

 cuticle, which finally scales off leaving a dark brown color with 

 olive borders. This is one of the worst diseases of the apple 

 and perhaps causes more damage than any other in this state. 

 It not only does harm itself by preventing the proper growth of 

 the fruit and leaves, but it opens the way for rot producing 

 fungi. Apples free from scab are usually much larger and 

 more regular than those affected by it. 



Hoiv spread: The spores are very small and are blown from 

 place to place or carried by the insects. 



'ireatment: Burn all the leaves in the fall or early spring and 

 cut out affected twigs. The disease may be checked by spray- 

 ing, as demonstrated by Professor Emerson: 



"Two sprayings with Bordeaux mixture, the first just before 

 the flowers opened and the second soon after the blossoms fell, 

 prevented practically all injury from apple scab both to the 

 foliage and the fruit. One spraying after the blossoms fell gave 

 nearly as good results. The results in detail are as follows. 

 The figures represent the percent of fruit free from apple scab: 



Sprayed Unsprayed 



