268 MANUAL OF FRUIT DISEASES 
five years. The roots on diseased plants decay first at the tip, 
then other parts succumb, and finally the whole system is 
involved. 
Cause. 
The disease is not only destructive but obscure. As yet the 
cause isnot known. It has been concluded by many authorities 
that it is of non-parasitic origin. They claim that over- 
bearing is not an impossible cause. It is also held that the 
disease is due to some weakness in the functions of absorption 
and translocation of water. There is some evidence that the 
causal factor, whatever its nature, is transmitted by cuttings. 
Control. 
The use of cuttings from healthy vines from a district where 
the disease does not occur is advised. Healthy cuttings, 
however, may contract the disease if grown among affected 
vines. 
REFERENCES 
Pierce, N. B. The California vine disease. U.S. Agr. Dept. Veg. 
Path. Div. Bul. 2: 1-222. 1892. 
Pierce, N. B. Grape diseases on the Pacific Coast. California vine 
disease. U.S. Agr. Dept. Farmers’ bul. 30:7-10. 1895. 
Butler, O. Observations on the California vine disease. Torrey 
Bot. Club Mem. 14: 111-153. 1910. 
