For analysis of the results of experiment A, leaf discs were further
separated in four classes according to the features given in
Table 2. In addition, it was defined that for the ‘‘infection +’’ class,
the degree of infection must have been at least 5% as determined
by visual inspection. ‘‘Contamination’’ was judged as ‘‘+’’ if secondary
microbial infection was visible for two days. For class C, neither
infection nor contamination should visible on any day. Replacement
of filter paper by plastic foam in experiment B, this classification
was not necessary because no contamination of leaf discs with
fungi other than Bremia occurred in plastic foam (see Table 3).