Insect and Fungous Enemies of the Grape. 61 
CROWN GALL OF GRAPE. 
Crown gall is a disease caused by a bacterium.** This germ is a 
wound parasite which, after gaining entrance to the root or cane 
of the vine, causes an abnormal gall, wart, or elongate tumorlike 
outgrowth, sometimes of considerable size, as shown in figure 70, 
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Fic. 68.—The dead-arm fungus. (1) Fruit bodies (pycnidia) ; (2) Section through 
one of these fruiting bodies. (38) Another section of smaller fruiting body. (4) 
Summer spores or pycnospores. (5) Sporophores. (6) and (7) Two forms of spores 
produced in the pycnidia. (8) Portion of dead cane showing perithecia. (9), 
(10), and (11) asci and spores from (8). All but (1) and (8) highly magnified. 
at other times of smaller size and very numerous, extending along 
the trunk or branches of the vine. 
The larger galls shown in figure 71 are most frequent on the Eu- 
ropean varieties of grapes which are grown on the Pacific coast and 
in the Southwest. The smaller and more numerous galls united in 
elongate masses are the common form on American varieties of 
® Bacterium tumefaciens Smith & Townsend. 
