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SPECIAL PLANT PATHOLOGY 



The rapidity of spread has been phenomenal, and the completeness 

 of destruction is without parallel in the annals of plant pathology. It 

 is now found from New Hampshire to Albemarle County, Virginia, in 

 the South. Summer is the best time to study the symptoms of the 

 disease, which are manifested in the brown shriveled leaves, which 

 may be seen at a distance. The dead leaves hang on the tree over 

 winter, and if on the blighted branches, the girdling is completed while 

 the burs are maturing. Burs smaller than usual, and unopened, re- 



FiG. 173. — Chestnut blight pustules producing gelatinous threads with summer 

 spores. (After pictorial card issued by Penna. Chestnut Tree Blight Com., 1912.) 



main attached to the tree through the winter months and well into the 

 next spring. If, however, the girdling takes place after the leaves and 

 burs are shed and before the leaves open in the spring, the leaves do 

 not attain their full size, but are pale and distorted and this is a com- 

 mon symptom during May and June. Dead limbs without attached 

 leaves, or burs, are often indications of the canker disease. Water 

 sprouts, or suckers, may develop just below the cankered regions of 

 the branches or stem and thick clumps of suckers on the trunk and 



