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Observation 14432: Bremia lactucae Regel

When: 2008-11-20

Collection location: Berkeley, Alameda Co., California, USA [Click for map]

Who: Chris Ahlgren (All Grin)

No specimen available


10X magnification. Stained with lactophenol blue.
40X magnification. Stained with lactophenol blue.
4X magnification. Stained with lactophenol blue.
10X magnification. Stained with lactophenol blue.

Proposed Names

68% (2)
Recognized by sight: In a family of obligate vascular plant parasites, Peronosporaceae, this geneus is found growing on the underside of lettuce leaves. Discoloration visible from the top and eventual wilt. Underside of leaf has Thin white powder to the naked eye which is the signature that gives this family it’s common name of Downy mildews.
Used references: Alexopoulos, C.J. “Intorductory Mycology”. 2002 John Wiley & Sons
Based on microscopic features: Lemon shaped conidia, Dichotomously branched conidiophore,

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= Observer’s choice
= Current consensus


Add Comment
By: William J. Davis (daviswj)
2020-12-07 08:25:22 PST (-0800)

Hi Chris,
Do you happen to know what the host species was?

Great shots!
By: Dan Molter (shroomydan)
2008-11-21 09:15:58 PST (-0800)

Nice microscopy work!