DISEASES OF THE APPI.E. 



245 



Twig and leaves of hybrid Prairie Crab apple showing cedar rust. 



Jonathan apple showing eedar rust on the fruits. 



How spread: The wind is undoubtedly the greatest agent in 

 •spreading rust. The spores are very light and are easily 

 •carried for long distances. Without a doubt insects play an 

 important part in the spread of the disease. 



'Treatment: The common recommendation has been to cut 

 down all the red cedar trees. It is certain that if there are no 

 red cedars in the community the apple trees will not be affected 



