THE GENUS PYTHIUM - An-Najah National University

PYTHIUM ROSTRA TUM Butler, Mem. Dep. Agric. bot. Ser.
Figs. 101-103
1:84 )1907)
COLONY MORPHOLOGY: Colonies on CMA showing a chrysanthemum
pattern; no development of aerial mycelium. MYCELIUM: Main hyphae 3-6
(av. 3.6) .um wide. SPORANGIA: Terminal or intercalary, globose and
subglobose, 15-35 (av. 23.1) .nm diam, zoospores produced at 10_20° C.
OOGONIA: Mostly intercalary, occasionally terminal, subglobose, smooth, 14-
25 (av. 18.7± 0.9-95% c.!.)..um diam, often in chains. ANTHERIDIA: 1-2 per
oogonium, monocIinous, often sessile originating immediately below oogonium
base, or hypogynous. OOSPORES: Plerotic (oospore volume/ oogonium volum-
0.75),13-23 (av. 17.0± 0-7-95% c.l.)..um diam, wall 1-2 (av. 1.3± 0.1-95% C.I.)
urn thick, ooplast 6-11 (av. 8.8) ..urn diam. TEMPERATURE-GROWTH
RELATIONSHIPS: Minimum 5' C, optimum 15-20· C, maximum 30C. Daily
growth rate on CMA at 25°C 5.6mm.
MATERIAL EXAMINED: ex Zea mays, Nassareyeh (FCCAU 119.25),
Citrus sinensis (L) Osbeck, Nablus (FCCAU 119.26); ex soil, Jenin (FCCAU
119.10), and many other isolates.
OCCURRENCE: Frequently isolated from diseased roots, and also
constantly present in soil (found in 85% of the soils sampled). This species was
also isolated from soil in the Lebanon (Ahrens, 1971) and Iraq (AI-Doory et al.
1959).
PYTHIUM SALPINGOPHORUM Drechsler, J. Wash. A cad. Sci. 20:507
(1930). Figs 109-114.
COLONY MORPHOLOGY: Colonies on CMA showing no special pattern;
no development of aerial mycelium. MYCELIUM: Main hyphae 3-6 (av. 3.6)
J.Im wide, occasionally developing elongated or ovate, often catenulate
appressoria present. SPORANGIA: Mostly terminal, occasionally intercalary,
sometimes catenulate, occasionally proliferating, subglobose to globose, 17-28
(av. 22.5) J.Im diam, zoospores produced at 10-26 C, emmision tube usually
formed near a septum. OOGONIA: Mostly intercallary, frequently in chains of
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