274 Peach-Growing 



Die-hack {Valsa leucostoma) 



The economic importance of this disease was apparently 

 first fully recognized in the United States by Rolfs/ who 

 in 1910 published the results of his studies. The occurrence 

 of the disease has been reported from many widely separated 

 points, and its distribution may be regarded as general 

 throughout the peach-producing sections of the country. 

 However, it is rather definitely associated with the depleted 

 vitality of neglected orchards. 



Course of development. 



In general the trouble begins with the appearance on the 

 twigs of small roughened or cankered spots which center 

 about the buds. Frequently, following an infection of the 

 twigs, the fungus works its way into large branches and 

 limbs, killing them one by one until the whole tree dies. 

 Sometimes the branches are girdled by the disease. The 

 progress of the malady varies more or less, however, being 

 governed evidently by the condition of the tree, climatic 

 conditions, and other influences. Doubtless many cases 

 of injury from this disease have been looked on as "sun- 

 scald," "winter-injury/' and the like. 



Methods of control. 



Rolfs points out that any methods of orchard manage- 

 ment which are conducive to the health and vigor of the 

 trees serve as preventive measures, since it is weakened or 

 unthrifty trees that are most severely attacked. Three 

 applications of weak bordeaux mixture in the fall and one 

 application of normal strength in the spring greatly reduced 

 1 Mo. State Fruit Expt. Sta. Bull. 17. 



