During the 2004 growing season, five raspberry cultivars were evaluated in terms
of their susceptibility to the raspberry cane midge (Resseliella theobaldi Barnes). The
trial was carried out at Berkenye, Nógrád County, Hungary. The cultivars evaluated
were ‘Rubaca’ from Germany, ‘Fertődi Zamatos’ from Hungary, ‘Tulameen’ from
Canada, and ‘Autumn Bliss’ and ‘Golden Bliss’ from the United Kingdom. Every
other week, twenty-five split primocanes of each cultivar were randomly collected for
laboratory examination. Data recorded for each cultivar included the mean number of
larvae, the mean split length, and the mean extent of bark peeling per primocane.
Pearson’s linear correlation coefficients were calculated for the correlations between
the annual mean number of larvae per primocane on the one hand, and the annual
cumulative mean split length per primocane and annual mean extent of bark peeling
per primocane on the other hand. There was a weak correlation between annual mean
number of larvae and annual cumulative mean split length, and a stronger correlation
between annual mean number of larvae and annual mean extent of bark peeling.
Annual mean number of larvae per primocane and annual mean extent of bark peeling
per primocane were both highest in ‘Rubaca’, which means that the number of larvae
per cane largely depends on the extent of stem peeling, although longitudinal splitting
may also play a role. Therefore, cultivars with hardly any bark peeling and few and
small longitudinal splits can be presumed to be less susceptible to infestation by the
raspberry cane midge. Using these criteria, the least susceptible of the five cultivars
evaluated would be ‘Tulameen’ and ‘Fertődi Zamatos’. Further research is needed to
confirm this conclusion and to gather data on other factors which affect cultivar
choice for new plantations, including winter hardiness, and susceptibility to cane
diseases