Phyllactinia guttata

Phyllactinia guttata
Various stages in the life cycle of Phyllactinia guttata. Fig 1. Natural size, on chestnut leaf. 2. Perithecium enlarged. 3. Two asci. 4.Three sporidia. 5.Conidia-bearing hyphae. 6.Conidium germinating.
Scientific classification
Kingdom:	Fungi
Phylum:	Ascomycota
Class:	Leotiomycetes
Subclass:	Leotiomycetidae
Order:	Erysiphales
Family:	Erysiphaceae
Genus:	Phyllactinia
Species:	P. guttata
Binomial name
Phyllactinia guttata (Wallr.) Lév.

Phyllactinia guttata is a species of fungus in the Erysiphaceae family; the anamorph of this species is Ovulariopsis moricola. A plant pathogen distributed in temperate regions, P. guttata causes a powdery mildew on leaves and stems on a broad range of host plants; many records of infection are from Corylus species, like filbert (Corylus maxima) and hazel (Corylus avellana). Once thought to be conspecific with Phyllactinia chorisiae, a 1997 study proved that they are in fact separate species.

Microscopically, P. guttata is characterized by large ascomata, long narrow pointed appendages with bulbous swellings at base, 2- or 3-spored asci with large ascospores; the ascomata also have gelatinous cells with tufts of hyphae somewhat resembling hairs. The cleistothecia are capable of dissemination and attachment to new growing surfaces by means of gelatinous penicillate cells.

Originally named in 1801 as Sclerotium erysiphe by Christian Hendrik Persoon, the species went through a number of name changes in the 1800s. Salmon's widely used 1900 monograph on the Erysiphaceae established the name as Phyllactinia corylea for roughly half a century, until the starting date for the naming of fungi was moved, and the name was established as Phyllactinia guttata.

The mycelium may be abundant and persistent, or scant and short-lived (evanescent). The cleistothecia can become large (216–245 µm), with soft wall tissue, and obscure cellular structure and cracks and wrinkles (reticulations).

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