[Chap. XLV 



PLANT DISEASES 



579 



condition that has given rise to the term "mummified fruit." When the 

 flowers are infected, "blossom bhght" occurs and results in the death 

 of the flowers. The fungus may grow from the blossoms into the twigs, 

 and there cause cankers and death of the twig. 



Fig. 261. Brown rot of peaches. Photo by J- A. McChutock, Georgia Experiment 



Station. 



New infections may occur from the time of early flowering until the 

 fruit is mature. Insects and winds are the principal means of spore 

 dispersal. The fungus may overwinter in mummified fruits and in twig 

 cankers. Control of the disease may be accomplished by thorough prun- 

 ing accompanied by removal of mummies and diseased twigs and the 

 application of the appropriate sulfur sprays or dusts throughout the 

 growing season. 



Peach leaf curl. Typical symptoms of peach leaf curl are pinkish, puck- 

 ered, and thickened leaves or parts of leaves. Infection of peach leaves 

 is most frequent when a cold wet period follows the parting of the 

 bud scales in spring. The mycelium invades the tissues and in a few 

 weeks a layer of asci fonns on the upper surface of the leaves. This 

 disease causes the early abscission of the leaves. Young shoots and 

 flowers are also infected and killed. The disease is easily controlled by 

 one application of a lime-sulfur or Bordeaux spray during the dormant 

 period before the buds begin to swell. 



Wood rots. Trees, fence posts, telephone poles, railroad ties, and 

 bridge timbers sooner or later decay, as the result of the activities of 

 certain wood-rotting fungi. These fungi nearly all belong to the groups 



