|
First Report of Ascochyta fabae on sainfoin
in Turkey
C. Eken*
Department of Plant Protection, Faculty of Agriculture, Atatürk
University, 25240 Erzurum, Turkey
* ceken@atauni.edu.tr
Accepted for publication 06/01/03
Sainfoin (Onobrychis viciifolia Scop.) is one of the
most commonly grown forage crops in Erzurum, Turkey. During the summer
of 2000 and 2001, a serious disease with typical blight symptoms was
observed in sainfoin fields in the province of Erzurum, Turkey. Initial
symptoms on leaves were more or less circular, slightly sunken with a
definite margin, and usually dark brown with a lighter centre in which
pycnidia developed (Figs. 1 and 2).
|
Figure 1: Ascochyta blight symptoms on leaves.
|
Figure 2: Pycnidia of Ascochyta fabae.
|
|
Figure 3: Stem lesions in Ascochyta blight often coalesce
to girdle stems.
|
Stem lesions were elongated, sunken and darker in
colour than leaf lesions (Fig. 3) with scattered pycnidia. Small
black pycnidia that produced a pink exudate containing hyaline,
straight, slightly truncate at the base and rounded at the apex,
1-3 septate (rarely 3 septate), 13 to 24 µm (average 18.1 ± 0.32
µm) x 4 to 6 µm (average 5 ± 0.06 µm) conidia under high
humidity were visible in the centre of the spots. The fungus was
consistently isolated on potato dextrose agar from diseased leaves
or stems, and identified as Ascochyta fabae Speg. based on
morphological characteristics of pycnidia and conidia (Ellis &
Ellis, 1985).
To satisfy Koch’s postulates, a conidial suspension (1.7 x 106
conidia per ml) of the fungus was sprayed onto leaves and stems of
sainfoin seedlings (15 weeks old) (cv. Erzincan). Both inoculated
seedlings and control seedlings (inoculated with sterile water)
were covered with plastic bags for 72 h in a glasshouse at 23 ± 2
oC. Inoculated plants showed characteristic symptoms of
Ascochyta blight 12 – 15 days after inoculation. The
fungus was reisolated from lesions that developed on the leaves
and stems of all inoculated plants but not from tissues on any of
the control plants. The pathogen has been recorded previously on
sainfoin in Iran, in 1996 (Sharifnabi & Fatehi, 1996). This is
the first report of Ascochyta fabae on sainfoin in Turkey. |
References
Ellis, MB, Ellis JP, 1985. Microfungi on Land Plants. London, UK:
Croom Helm Ltd.
Sharifnabi, B, Fatehi, J, 1996. Ascochyta blight of sainfoin in Iran.
Iranian Journal of Plant Pathology, 32, (1-2): 29
|
