CHAPTER IX 

 BASSWOOD DISEASES 



The several species of basswood or linden (Tilia) are 

 common in eastern and central United States. These trees, 

 as well as several European basswoods, are extensively used as 

 shade and ornamental trees in the same region. 



No serious diseases affect the basswood. Several leaf-spots 

 and one powdery mildew affect the leaves occasionally. The 

 sapwood may be destroyed and the trees killed where wood- 

 peckers damage the bark and allow fungi to enter. In the 

 South the roots of the basswood are often decayed by a fungus 

 which is common in heavy soils. 



Powdery Mildew 



Caused by Uncinula Clintonii Peck 



This powdery mildew fungus attacks the leaves of basswood 

 in northeastern and north central United States. The myce- 

 lium is visible on both sides of the leaf, causing diffused 

 powdery white patches. Small black fruiting-bodies which are 

 just visible to the unaided eye are scattered over the whitish 

 area. This species, although indistinguishable from other pow- 

 dery mildew fungi, except by microscopic characters, is so far 

 the only one reported on basswood leaves. The life histories 

 and methods of control of powdery mildew fungi are discussed 



on page 37. 



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