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 is not 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. Bui. 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. 



