© Benaki Phytopathological Institute
Hellenic Plant Protection Journal - Special Issue
26
A foliar disease of holly (
Ilex aquifolium
L.)
was observed in 2009 in a natural ecosys-
tem in the region of Thessaloniki (Northern
Greece, Central Macedonia, Mount Hortia-
tis). Symptoms consisted of circular, some-
times irregularly shaped, brown necrotic
spots with yellow border, 3 to 7 mm in di-
ameter. On some leaves several spots co-
alesced to form large necrotic areas, cover-
ing approximately half of the leaf surface.
Older lesions sometimes appeared black-
ish brown as sporulation occurred on the le-
sions. The percentage of diseased leaves of
the particular population was approximate-
ly 30%. Single spore cultures on potato car-
rot medium (PCA) gave rise to initially white
colonies which turned to grayish-black lat-
er due to abundant sporulation. Conidio-
phores were short, septate, branched or
unbranched, and green to brown. Mature
conidia were produced in long, single or
more often in branched chains. The conid-
ia were obpyriform, with a conical or cylin-
drical beak, ovoid or ellipsoidal measuring,
7.7 – 27.4 x 5.6 -15.0 μm (average 16.3 x 8.8
μm), showing 1 to 5 transverse septa and 0
to 3 longitudinal septa. These data, togeth-
er with molecular characterization using the
specific ribosomal internal transcribed spac-
er region (rDNA-ITS) confirmed the identi-
ty of the fungus as
Alternaria alternata
(Fr.)
Keissl. A pathogenicity test was conduct-
ed on detached, wounded and unwound-
ed, healthy
I. aquifolium
leaves. Ten days af-
ter inoculation, leaf spots similar to the ones
observed in the field developed on all the
inoculated points (wounded leaves) and on
half of the unwounded leaves, while control
leaves remained symptomless.
A. alterna-
ta
was reisolated from artificially inoculated
leaves confirming Koch’s postulates. To our
knowledge, this is the first report of
A. alter-
nata
causing leaf spot on holly in Greece.
