Abstract Effective planning of the control of the white-pine blister rust in the sugar pine forests of southern Oregon requires a knowledge of the susceptibility to the rust and capacity to produce pine-infecting spores of the ribes of that region, ribes being the alternate hosts of the causal fungus. To secure this information, over 300 plants of the principal ribes of southern Oregon (8 species, one of which has 2 varieties) were placed in an experimental garden on the Mt. Hood National Forest where they were tested under heavy rust-infection conditions. Results of the tests, conducted over a period of three years, show that all these species are congenial hosts for the rust and should be eradicated as a protective measure in those areas where it is desired to maintain sugar pine forests.
James W. Kimmey (Tue,) studied this question.