18 FIELD STUDIES OF THE CROWN-GALL OF THE GRAPE. 



Data collected from nearly a hundred vineyards in six States in 

 the southwestern and western United States yield similar conclusions 

 as to the susceptibility of varieties. The most diseased varieties 

 observed among those commonly grown in vineyards, taken in order 

 from the highest percentage of disease to the lowest, were as follows : 

 Muscat of Alexandria, Malaga, Mission, Flame Tokay, Black Mal- 

 voisie, and Zinfandel. Of varieties grown to a much less extent the 

 following, arranged in the same order as before, were also found badly 

 diseased: Black Morocco, Purple Damascus, Early Madelaine, Black 

 Prince, Trousseau, Zabalkanski, Verdel, and Burgundy. 



Among the vines commonly grown, those observed to be least 

 affected by the disease, in the order of their immunity, were the fol- 

 lowing: Seedless Sultana, Sweetwater, Lenoir, Thompson Seedless, 

 Feher Szagos, and Burger. 



Of the vines grown to a lesser extent, the least diseased, taken in 

 the same order as before, were Carignane, Gros Colman, Mataro, 

 Black Prince, Black Portugal, and Grenache. 



Of stocks for grafting, the Rupestris St. George, Rupestris Martin? 

 and Herbemont appear to be almost immune. 



THE RESISTANCE OF VARIETIES OF AMERICAN GRAPES. 



The writer conducted no vineyard experiments with varieties of 

 American grapes, but secured data from a number of vineyards in 

 which the disease had appeared. Through the courtesy of Prof. 

 W. G. Vincenheller, director of the Arkansas Agricultural Experiment 

 Station, notes were taken on a vineyard at the station in which there 

 was a large number of varieties of American vines and their hybrids. 

 These vines were about 12 years old, and the disease had been 

 observed in the vineyard for a number of years. The vines were 

 planted on gently sloping land, consisting of an upland clay loam. The 

 diseased vines were chiefly on the upper side of the vineyard, in such 

 a position that the water ran from them to the vines lower down. 

 The cultivation of the plat was made at right angles to the line of 

 drainage, thus tending to spread the germs of disease throughout the 

 plat by cultivation and drainage. 



In the table and lists which follow the results of the experiment are 

 given. The names of species of grapes here and elsewhere in this 

 bulletin are in accordance with those used in Bailey's "Cyclopedia of 

 American Horticulture." The data on the ancestry of each variety 

 were furnished by Dr. George C. Husmann, Pomologist in charge of 

 Viticultural Investigations of this Bureau. 



183 



