Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

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Session 2 — P. Halama, F. Lalaoui, V. Dumortier, and B. Paul
at day 10, 6 and 14 for A/5, 6/T
and 300.2 isolate respectively.
Acetyl-esterase and β-galactosidase
activities were also detectable for
all three isolates.
Aggressiveness of P.
nodorum isolates
The pathogenicity test allowed
us to distinguish two groups of
isolates according to their
aggressiveness (Table 2). Significant
differences in the average of
necrosis symptoms were conclusive
for differentiating the A/5 isolate
from isolates 6/T and 300.2. The
A/5 isolate of P. nodorum produced
longer lesions on detached leaves
than did the other two isolates 6/T
and 300.2. Furthermore, there was
partial correlation between the
incubation period and length of
necrotic lesions; the longer lesion of
A/5 was related to a short latent
period, but the similar lengths of
necrotic lesions caused by 6/T and
300.2 were unrelated to their
incubation periods.
Discussion
Results reported here constitute
the first report on the relationship
between aggressiveness and in vitro
production of CWDEs by P.
nodorum. Our study indicated that
Table 2. Lesion length and incubation period
on detached leaves of wheat (cv. ‘Soissons’)
caused by isolates of Phaeosphaeria nodorum
10 days after inoculation.
Lesion Incubation
length period 1
Isolate (mm) (hours)
A/5 9.78 a 2 43
6/T 3.60 b 63
300.2 3.53 b 41
1 The incubation period was determined by
measuring the period between inoculation and
the moment when 50% of the detached leaves
presented visible lesions.
2 Within a column, means followed by different
letters are significantly different according to t
test (P