BULLETIN No. 39. CALIFORNIA JANUARY 1920. RED CEDAR TREES AND CEDAR RUST A REPORT OF A CEDAR RUST SURVEY OF BY ROY E. MARSHALL, HORTICULTURIST, AND F. D. FROMME, PLANT PATHOLOGIST. VIRGINIA AGRICULTURAL AND MECHANICAL COLLEGE AND POLYTECHNIC AGRICULTURE, COOPERATING. EXTENSION DIVISION, JNO. R. HUTCHESON, DIRECTOR. ASSISTANCE THAT CAN BE RENDERED BY THE EXTENSION DIVISION OF THE VIRGINIA POLYTECHNIC INSTITUTE. The Extension Division carries the Agricultural College and United States Department of Agriculture to the farmer and farm home. It endeavors to meet their problems in soils and crops, horticulture, dairying, live stock, poultry, agricultural engineering, home economics and community development. This is done by personal visits, meetings, and correspondence of County Farm and Home Demonstration Agents and Specialists, through boys' and girls' and women's club work, cow testing and purebred live stock and other associations and organizations, and the distribution of bulletins, circulars, newspaper articles, etc. Application for information or assistance with any farm or home problem should be made to the Director of the Extension Division, Blacksburg, Virginia. V Red Cedar Trees and Cedar Rust A Report of a Cedar Rust Survey of Augusta County, Virginia. BY ROY E. MARSHALL AND F. D. FROMME At the request of the fruit growers, a cedar rust survey was conducted in Augusta County, Virginia, during the last week in August, 1919.* The purpose was to determine the relation between the severity of cedar rust infection on apple foliage and the number of red cedar trees in the vicinity of orchards. The season of 1919 was unusually favorable for cedar rust infection, and a severe epidemic developed. The losses were intensified by a period of drought in late summer, but this was general for the county, and therefore did not modify the relative losses from cedar rust as presented in this report. There had been some eradication of cedars in the county in former years, and the general impression seemed to be that this work had been of slight value as a protection to apple orchards. The question was raised as to whether removal of cedars is of any direct benefit to the fruit grower. The survey was planned to obtain an answer to this question, to determine whether the severity of cedar rust varies according to the numbers of cedars in the vicinity of the orchards, and whether orchards which are practically free from cedars produce better crops than those with many cedars nearby. York Imperial is the most susceptible of the commercial varieties grown in the county and the one on which the bulk of the losses are sustained. The survey was, therefore, limited to those orchards which contained trees of this variety of bearing age, and all the data on cedar rust infection and fruit yields were drawn from this variety alone. Of the 148 orchards visited, 113 met these requirements, the remainder being of less susceptible varieties or of non-bearing age. The 113 orchards. contained a total of 72,235 trees of the York Imperial variety. Data were secured in each orchard on the following: severity of rust. infection on the foliage, amount of defoliation, size of fruits, vigor of *The survey was a cooperative project between the Extension Division, the Agricultural Experiment Station, and the Crop Pest Commission. The writers are indebted to Mr. W. J. Schoene for assistance in this work. R. R. Reppert, C. Woolsey, Kent Apperson and J. F. Eheart assisted in making the survey. The work was made possible through the hearty cooperation of the fruit growers in the county. (3) The accompanying map shows the general facts of the survey. The orchards are numbered and indicated by circles, a black circle showing severe infection; half black, moderate infection; and clear, slight infection. The location of cedars is shown by crosses. A study of the map shows that, in general, there is a very complete agreement between the severity of rust infection and the number of cedars in the vicinity of the orchards. Severe rust infection occurs where there are many cedars in the vicinity, and slight rust infection where there are few or very few |