Trees and Timber 



401 



persist for many years. One stage of this rust occui's ui)on 

 the oalvs. 



Rust {Coleosporiavi soUdagiiiis (Schw.) Thihii., Perider- 

 mium). — Another species of Peridermiuni occurs upon 

 leaves, producing small, sac-like, tubular outgrowths which 

 contain the spores. This is a stage of 

 a rust which appears later in the season 

 upon golden-rods and asters. 



Red-rot {Fonies pinicola Cke.). — 

 Upon dead trees this rot begins just 

 under the bark, usually near the tree 

 top, often following bluing. The wood 

 is at first wet and soggy, but soon 

 becomes brittle, so that it crumbles 

 readily. The cracks become filled with 

 felted fungous threads. The sporo- 

 phores first appear as fleshy knots, 

 soon red, which widen to pore-bearing 

 shelves. 



POPLAR, COTTONWOOD 



Rust (Melampsora sps.). — This is 

 similar to willow rust. See p. 405. 



European-canker "*-- (Dothichiza pop- 

 ulea S. & B.). — Species of poplar and 

 Cottonwood in nine states show this 

 disease. Death of the cambium re- 

 sults, and following this numerous can- 

 kers and dead branches render the trees 

 unsightly. The disease was probably 

 recently imported on the Lombardy 

 poplar from Europe. New stock should 

 be carefully inspected. Infected wood 

 should be cut out and burned. 



Canker '"^^ (Cytospora chnjsosperma (Pers.) Fr.). — This 

 serious canker is prevalent in the southwestern United States 



Fig. 213. — Pine 

 needle, bearing clus- 

 ter-cup of rust, en- 

 larged. After Clin- 

 ton. 



