CHAPTER XXVII 

 PINE DISEASES 



Over thirty species of pine (Pinus) occur as forest-trees in the 

 United States. No region of the country where trees grow is 

 without representatives of this important group. A large part 

 of the timber of the coimtry is made from pines. The various 

 native pines and many exotic species and varieties are used 

 for ornamentals. 



Pine is subject to many destructive diseases wherever it 

 grows. The most important of these are root-rots, wood-rots, 

 blister-rusts, mistletoe injury, leaf-cast and various types of 

 winter-injury. The importance of these types of diseases 

 varies with the species and region of the country in question. 

 Pecky wood-rot and the different blister-rusts of the branches 

 and trimks probably cause the most damage. The white pine 

 of the northeastern states was reasonably free from important 

 diseases until the introduction from Europe of the blister-rust 

 fungus. Pines outside of the forest often suffer severely from 

 winter-drying and other types of injury due to extremes in 

 temperature. 



Seedling Root-Rot 



Caused by Rhizina undvlata Fries 



The seedlings of several species of pines in the forests of 

 northwestern United States are killed by this root-rot. The 

 fungus is also present in several eastern states and may cause 

 similar damage. The roots cf seedlings three to six years old 

 are killed. Examination shows the roots and a quantity of 



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