THE GENUS PYTHIUM - An-Najah National University
THE GENUS PYTHIUM - An-Najah National University
THE GENUS PYTHIUM - An-Najah National University
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<strong>PYTHIUM</strong> TRACHEIPHILUM Matta, Phytopath. medit. 4:51(965)<br />
Figs 116-117<br />
OCCURRENCE: Rarely isolated from irrigated soils (found in 9% of these<br />
soils); it was not detected in nonirrigated soils.<br />
<strong>PYTHIUM</strong> ULTIMUM VAR SPORANGIIFERUM Drechsler, Sydowia<br />
14:107(1960) (as 'sporangiferum'),<br />
This variety differs from var ultimum by its production of zoospores at room<br />
temperature.<br />
OCCURRENCE: Rarely isolated from soil; it was infrequently isolated from<br />
a citrus orchard near Nablus.<br />
<strong>PYTHIUM</strong> ULTIMUM VAR ULTIMUM Trow, <strong>An</strong>n. Bot. 15:300(1901)<br />
Figs 118-120<br />
COLONY MORPHOLOGY: Colonies on CMA forming a diffuse pattern<br />
with some aerial mycelium. MYCELIUM: Main hyphae 3-7 (av. 4),um wide.<br />
SPORANGIA and zoospores not formed. HYPHAL SWELLINGS: Globose,<br />
intercalary, sometimes terminal, 20-35(av. 25.3± 1.7-95% c.1.) .nm diam.<br />
OOGONIA: Terminal, sometimes intercalary, smooth, 16-35 (av. 20.8± 0.5-95%<br />
C.I) JIm diam. AN<strong>THE</strong>RIDIA: 1(-3)/ oogonium, monoclinous, mostly sessile<br />
originating just below oogonium base, occasionally hypogynous or dic1inous.<br />
OOSPORES: Aplerotic, 13-24 (av. 17,0± 0.5-95% c.r.i urn diam, wall 1-1.5 (av.<br />
1.2± 0.1-95% C.I.).llm thick, ooplast 7-14 (av. 1O± 0.4-95% C.I.).llm diam.<br />
o<br />
TEMPERATURE-GROWTH RELATIONSHIPS: Minimum 5 C, optimum<br />
250C, maximum 30oC. Daily growth rate on CMA at 250C 14mm.<br />
60
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