Tar Spot
(Rhytisma acerinum)
| Occurrence | Uncommon in Minnesota because the host is uncommon |
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| Season | Spring to fall |
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| Identification | This is a parasitic fungus infecting several species of maple (Acer). In Minnesota it infects only Norway maple. In the spring the infection appears as a yellow spot on the leaf. These turn first brownish-black with a yellow border, then, in late summer, black with a yellow border. The black spots resemble tar. The spots are solid, not a cluster of small spots. They may be up to 1½″ in diameter but are usually much smaller. The fungus is somewhat tollerant of air pollution and is often found in suburban locations. |
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| Similar Species |
Speckled Tar Spot (Rhytisma punctatum) causes dense clusters of very small black spots. Tar Spot (Rhytisma americanum) infects red maple and silver maple. |
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| Distribution | .png "Distribution Map") |
Until 1998 this species name included what is now recognized as Rhytisma americanum. Some or all of the records represented on the map at left may be Rhytisma americanum. |
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| Comments |
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| Taxonomy | Division: |
Ascomycota (ascomycetes) |
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| no rank: | saccharomyceta |
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Subdivision: |
Pezizomycotina |
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No Rank: |
leotiomyceta |
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sordariomyceta |
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Order: |
Rhytismatales |
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Family: |
Rhytismataceae |
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| The life cycle of this and most other fungi is pleomorphic. It has both an asexual reproductive phase (anamorph) and a sexual reproductive phase (telemorph). Each phase is often morphologically distinct. In the past, the International Code of Botanical Nomenclature allowed each phase to be assigned a different scientific name. It was incorrect to refer to the anamorph phase by the telemorph name, and vice versa. Some mycologists and molecular biologists consider this practice to be obsolete. Molecular phylogeny allows the accurate placement of a species in any part of their life cycle. On July 30, 2011, at the meeting of the XVIIIth International Botanical Congress in Melbourne, Australia, that practice ended. Prior to that meeting, the early, anamorphic phase of this fungi had been named Melasmia acerina. Both phases are now named Rhytisma acerinum. | |||||||
| Synonyms | Melasmia acerina Xyloma acerinum |
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| Common Names |
Sycamore Tarspot Tar Spot |
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Visitor Photos |
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MinnesotaSeasons.com Photos |
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| Slideshows | ||
| Rhytisma acerinum - fungi kingdom Nineli Lishina |
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About
Published on Jan 25, 2015 Rhytisma acerinum - fungi kingdom |
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| Other Videos | |||
| Insights into Nature - Tar Spot Fungus on Sycamore Roger Griffith |
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About
Published on Oct 27, 2014 The Tar Spot (Rhytisma acerinum) is a very common ascomycete fungus that typically grows on Celtic Maple / Sycamore (Acer pseudoplatanus) leaves giving a prominent black spot or spots on the leaf lamina, upper and lower epidermal surfaces. It is reported to grow occasionally on Norway Maple (Acer platanus) leaves. |
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MinnesotaSeasons.com Sightings |
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