CHAPTER XIII 



BUTTERNUT DISEASES 



The butternut (Juglans cinerea) throughout its range in 

 eastern and central United States is subject to a few diseases 

 only. The most important of 

 these is the leaf-spot, which 

 also affects walnut and hickory. 

 This disease often causes a part 

 or all of the leaves to fall from 

 the tree in midsummer. Oc- 

 casionally the brown checked 

 wood-rot and common white 

 wood-rot are found in butter- 

 nut. 



Leaf-Spot 



Caused by Marssonia juglandis 

 (Lib.) P. Magnus 



This is the common leaf- 

 spot of butternut and walnut. 

 Irregular dark brown spots ap- 

 pear on the leaflets in early 

 summer. When infection is 

 abundant, a large amount of 

 the leaf-tissue is killed and the 

 leaves fall from the tree. The illustration shows a single 

 leaflet affected by this disease (Fig. 15). 



The parasitic fungus causing the spots forms inconspicuous 



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Fig. 15. — Leaf-spot of butternut. 



