a A resistant (R) rating does
not mean that a particular cultivar will be resistant in all locations
every year. Due to the presence of physiological races or strains of
the various fungi that cause these diseases, a cultivar may be susceptible
in one locality and highly resistant in another. This is especially
true of powdery mildew and is the reason we omitted this disease from
our ratings.
b A blank under a given disease
does not necessarily indicate susceptibility. In some cases it means
that no data are available on which to evaluate the relative susceptibility
or resistance to a particular disease.
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