Nov., 1921] HOERNER — ^ STUDIES ON THE CROWN RUST OF OATS 457 
oat leaves is a common phenomenon though not correlated with resistance 
or susceptibility. 
8. The appearance of telia on seedling oat leaves is not a reliable basis 
for determining the resistance of oat varieties. 
Department of Botany and Plant Pathology, 
Oregon Agricultural College, 
CoRVALLis, Oregon 
LITERATURE CITED 
1. Hoeraer, G. R. Biologic forms of Puccinia coronata on oats. Phytopath. 18: 309-314. 
1919. 
2. McAlpine, D. The rusts of Australia, pp. 349. Melbourne, 1906. 
3. Christman, A. H. Observations on the wintering of grain rusts. Trans. Wis. Acad. 
Sci., Arts, and Lett. 15^: 98-109. 1904. 
4. Reed, H. S., and Holmes, F, S. A study of winter resistance of the uredospores of 
Puccinia coronata. Va. Agr. Exp. Sta. Ann. Rept. (1911-12): 18-21. 1913. 
5. BoUey, H. L., and Pritchard, F. J. Rust problems. Facts, observations and theories. 
Possible means of control. N. Dak. Agr. Exp. Sta. Bull. 68: 608-672. 1906. 
6. Mains, E. B. The relation of some rusts to the physiology of their hosts. Amer. Jour. 
Bot. 4: 179-220. 1917. 
7. Wheldale, M. The anthocyanin pigments of plants, pp. 83. Cambridge, 1916. 
8. Parker, J. H. Greenhouse experiments on the rust resistance of oat varieties. U. S. 
Dept. Agr. Bull. 629. 1918. 
EXPLANATION OF PLATE XXIV 
Fig. I (above). At "D"the teliospores formed on etiolated seedling oat leaves are 
shown; at "L" the normal production of urediniospores on the seedlings kept in the light. 
Fig. 2 (below at left). Avena sterilis L. infected with Puccinia coronata Cda. "S" 
shows the production of telia and of extensive dead areas by the Saint Paul, Minnesota, 
strain of rust. "T" shows normal production of urediniospores by the Tallulah, Louisiana, 
strain. 
Fig. 3 (below at right). Oats, Alabama-Appier 617, infected with P. coronata Cda. 
At "T" normal production of urediniospores by the Tallulah, Louisiana, strain of rust is 
shown; at "S," the heavy production of telia surrounded by hypersensitive areas produced 
by the Saint Paul, Minnesota, strain. 
