Abstract :
Spring barley cultivars currently grown in Germany are
all more or less susceptible to Rhynchosporium secalis
(Oudem.) J.J. Davis, but there are obvious differences in
the degree of susceptibility under field conditions. Small
genotypic differences may be caused by both genetic and
environmental effects, respectively. To minimize the
influence of environmental variation on disease
expression, several inoculation methods were developed
in the present study. In two experiments the effectiveness
of the inoculation by spraying of single spore isolates was
tested in the glasshouse and in the field, respectively. High
infection levels were achieved in the glasshouse. Despite
the infection of barley in the field, disease expression
levels remained low due to unfavourable conditions.
Another experiment showed the usefulness of infected
straw applied in the autumn only for testing the seedling
infection type of spring barley cultivars against R, secalis.
Seedling assay scores and field infection levels were
closely related (r = 0.796, P < 0.01; r = 0.911,
P < 0.001). Therefore, both the spray infection technique
in the glasshouse and the inoculation technique using
infected straw in the field appear to be suitable to detect
genetic differences in resistance/susceptibility of spring
barley cultivars against leaf blotch.
