PINE DISEASES 287 



Cordrol. 



In the western forests, the grazing animals keep the Castilleja 

 plants down to a minimum. Where grazing is not common, 

 these plants grow in large numbers and predispose the pines 

 to infection. All Castilleja plants should be eradicated for a 

 distance of a half mile around niu-series in which the species 

 susceptible to this rust-fungus are grown. 



Rbperencbs 



Weir, J. R., and Hubert, E. E. A serious disease in forest nurseries 

 caused by Peridermium fllamentosum. Jour. Agr. Res. 5 : 781- 

 785. 1916. 



Hedgcoek, G. G. Notes on some western Uredinese which attack 

 forest trees. II. Phytopathology 3 : 15-17. 19l3. 



Oak Rust 



Caused by Cronartium cerebrum (Peck) Hedgcoek and Long 



The blister-rust of pines, which is here called the oak rust, 

 is generally distributed throughout the United States. It has 

 been found on a large number of species of two- and three- 

 needle pines ; lodge-pole, jack, western yellow, short-leaf, Mon- 

 terey, Sabine, long-leaf, pitch, Jeffrey, loblolly, scrub, gray, knob- 

 cone-. Coulter, Pifion, Norway, sand, spruce and pond. Con- 

 siderable damage is caused to certain of these species in different 

 sections of the country. Along the Atlantic CoSst and in the 

 southern Appalachian Mountains, scrub pine is severely dam- 

 aged. In Michigan and Minnesota the jack pine is affected to 

 the extent that on dry lands fifty per cent of the trees are dam- 

 aged. In swamps practically every tree contains one or more 

 galls and witches'-brooms. In the west, the Sabine, twisted, 

 Monterey and knob-cone pines are the most susceptible species. 



Symptoms. 



Three types of injury are produced on the affected pines 

 of all ages. When the young leafy branches are infected. 



