Promising selections were obtained in breeding for improved yield potential through selection for high expression of individual yield components. A cane inoculation technique proved valuable for assessing cane resistance to Botrytis cinerea, Leptosphaeria coniothyrium and Didymella applanata.
In a diallel cross study, a strong positive interaction for resistance to botrytis fruit rot was found in a cross between a firm-fruited parent and a parent which has cane resistance to B. cinerea. High fruit resistance probably needs both of these components. A survey showed that black raspberries, R. pileatus and R. crataegifolius are good sources of fruit resistance.
Ability to show symptoms of infection to two latent viruses was determined by genes Ls and Lm respectively, immunity from Raspberry bushy dwarf virus was determined by gene Bu and immunity from Raspberry vein chlorosis virus probably by a recessive gene.
The Tayberry, a new raspberry-blackberry hybrid, is proving a success, but erect and spinefree forms are needed. Erect types have been obtained from segregation. To obtain spinelessness, there is progress in trasnferring dominant factors to the Tayberry, to its raspberry parent and to blackberries.