B. P. I.— .-,75. 



FIELD STUDIES OF THE CROWN-GALL OF 



THE GRAPE. 



INTRODUCTION. 



A disease of grapevines, under the various names of "black-knot," 

 "crown-knot," "root-knot," "crown-gall," and "root tumors," has 

 been known in the United States for many years. As early as 1880 

 it had become common in California (61) a and often resulted in 

 serious injury to the vineyards. With the introduction of Euro- 

 pean vines into new localities the disease has become widespread. 



During 1903 Prof. Fabian Garcia, of the New Mexico Agricultural 

 Experiment Station, found that a disease was killing the grapevines 

 at Bernalillo, N. Mex. The station having no plant pathologist the 

 Bureau of Plant Industry was requested to make an investigation of 

 the epidemic, and the task was assigned to the writer. 



A preliminary examination of the vines revealed the presence of 

 galls in large numbers on the canes and roots of many of them. 

 Experiments were at once undertaken for the control of the disease 

 and the cure of the diseased vines. After a thorough test of ordinary 

 remedies with little or no results, an experiment was conducted to 

 find varieties resistant to the disease. 



Meanwhile studies were made of the cause, nature, communica- 

 bility, and effect of the disease. This involved a number of species 

 and varieties of grapes and a series of experiments in the greenhouse 

 and gardens at St. Louis, Mo., and later at Washington, D. C. 



This bulletin outlines the history of the disease and gives the results 

 of these studies and experiments, which are of a preliminary nature, 

 but are of great importance, especially to growers of grapes in Texas, 

 New Mexico, Arizona, and California. Certain varieties of grapes 

 are found to be so susceptible to crown-gall as to be unprofitable for 

 vineyards in many localities, while others are resistant to a con- 

 siderable degree and are recommended for planting. Methods for 

 the prevention and control of the disease are outlined. 



a The serial numbers in parentheses used in this paper refer to the bibliography 

 which will be found on pages 31 to 33. 



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