AbstractThe incidence of spur blight (Didymella applanata), grey mould disease of the canes (Botrytis cinerea) and cane spot (Elsinoe veneta) was recorded for alternative forms of cane morphology which segregated in families of raspberry seedlings. Spur blight was less frequent on seedlings with hairy, spine-free, wax-free or non-pigmented canes, and also on seedlings whose canes had a moderately dense wax covering. The incidence of grey mould was influenced in a similar way except that it was slightly greater on the wax-free canes; and the incidence of cane spot was also similar to that of spur blight in its relationship to spininess, wax thickness and pigmentation, but was greater on hairy and on wax- free canes. Three years’ data for spur blight showed that the effectiveness of the cane characters in influencing liability to this disease was greater in 1960 than in 1959 and greater still in 1961. It is concluded that the characters mentioned confer on the cane surfaces properties which enable them to avoid infection by the fungal pathogens, and some evidence is given on the possible nature of these properties and on some factors which might influence their effectiveness. The incidence of spur blight and of grey mould, but not that of cane spot, appeared to be influenced to a greater degree by these properties than by tissue resistance. An alternative hypothesis postulating the close linkage of genes for tissue resistance with those determining cane morphology is thus more readily applied to cane spot than to the other two diseases. Under the conditions prevailing at Mylnefield, seedlings selected for cane hairiness and spinelessness possessed an adequate level of protection against each disease, particularly where they occurred in material possessing some degree of tissue resistance.