RASPBERRY DISEASES 405 
similar factors. Authorities agree that fungi cannot be the 
cause. Likewise entomologists say that insects are not con- 
cerned. The red spider has been suspicioned, but conclusive 
evidence is lacking. If bacteria are the cause, they have not 
been seen. It is possible that they are present, but are so very 
small that they are easily overlooked. It has been noticed 
that the disease is more pronounced where plants were growing 
in soil which had a high water table. Plants growing on soil 
having compactness and lacking drainage are more liable to 
exhibit yellows than lighter well-drained soils. It has been 
suspicioned as having some connection with crown-gall and 
cane-blight, but careful observations do not substantiate this 
view. 
Control. 
No preventive measures are known, and little hope is in sight 
until the causal nature is understood. Fungicides have proved 
themselves worthless in controlling the disease. A few rec- 
ommendations have been suggested, and the more important 
of these may be noted: (1) in planting red raspberries obtain 
plants from localities where raspberry-yellows is known not 
to occur; (2) select varieties which have shown resistance in 
the neighborhood; (3) select for a plantation-site a light, or 
medium-heavy, adequately drained soil; (4) irrigation is help- 
ful where practiced ; (5) destroy diseased plants. 
REFERENCES 
Stewart, F. C., and Eustace, H. J. Raspberry cane blight and rasp- 
berry yellows. II. Raspberry yellows. New York (Geneva) 
Agr. Exp. Sta. Bul. 226 : 362-364. 1902. 
Melchers, L. E. A preliminary report on raspberry curl or yellows. 
Ohio Naturalist, 14: 281-288. 1914. 
Green, S. B. Leaf curl of raspberry. Minnesota Agr. Exp. Sta. Ann. 
rept. 1894:230. 1895. 
