Cedar Apple Rust Gymnosporangium juniperi-virginianae Schweinitz    
Kingdom Fungi   >   Phylum Basidiomycota   >   Class Pucciniomycetes   >   Order Pucciniales   >   Family Pucciniaceae   >   Genus Gymnosporangium   

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This parasitic fungus with two alternating hosts, at different stages of its life cycle, is a major agricultural pest. Galls on stems of Eastern Redcedar trees produce jelly-like orange horns that bear spores. These spores infect apple leaves. In turn, the small dense yellow spore case clusters on apple leaves disseminate spores that produce the galls found on cedars (J. Solem, pers. comm.).

In addition to apple, certain other members of the Rose Family (Rosaceae) may also be infected by Cedar Apple Rust, including crabapple, hawthorn (Crataegus species), and serviceberry (Amelanchier species). These plants suffer more damage from the fungi than do the cedars, which are relatively resistant.

Cedar Apple Rust fungi overwinter on cedar trees as hard, dull-brown galls. The galls put out the gelatinous "horns" in response to spring rains, and the spores released are carried by wind or insects to the alternate host trees. During dry spells, the horns of the galls on the cedar shrivel, to reawaken with new rain.

There are 192 records in the project database.

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Cedar Apple Rust, overwintering gall, in Prince George's Co., Maryland (2/22/2013). (c) Sam Droege, some rights reserved (CC BY). Photo by Sam Droege. (MBP list)

Cedar Apple Rust in Howard Co., Maryland (5/1/2013). Shown here are mature spore-bearing structures on Eastern Redcedar host. Photo by Joanne Solem. (MBP list)

Cedar Apple Rust in Talbot Co., Maryland (3/26/2016). Photo by Dan Small. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (5/11/2015). Photo by Bonnie Bell. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (4/2/2017). Photo by Robert Ferraro. (MBP list)

Cedar Apple Rust in Cromwell Valley Park, Baltimore Co., Maryland (5/1/2013). Photo by Benjamin DeHaven. (MBP list)

Cedar Apple Rust on a Crab Apple leaf in Howard Co., Maryland (8/7/2016). Photo by Richard Orr. (MBP list)

Cedar Apple Rust in Frederick Co., Maryland (5/9/2015). Photo by Mark Etheridge. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (4/30/2016). Photo by Barbara Thurlow. (MBP list)

Cedar Apple Rust in Calvert Co., Maryland (5/5/2016). Photo by Tyler Bell. (MBP list)

Cedar Apple Rust in Anne Arundel Co., Maryland (5/2/2016). Photo by Tyler Bell. (MBP list)

A Cedar Apple Rust in St. Mary's Co., Maryland (5/1/2013). Photo by Patty Craig. (MBP list)

A Cedar Apple Rust in Calvert Co., Maryland (5/16/2014). Photo by Bill Hubick. (MBP list)

Cedar Apple Rust (winter gall) on Eastern Redcedar in Washington Co., Maryland (12/27/2014). Photo by Jane Hill. (MBP list)

Cedar Apple Rust (winter gall) in Harford Co., Maryland (1/16/2017). Photo by Dave Webb. (MBP list)

Cedar Apple Rust (winter gall) in Worcester Co., Maryland (2/20/2016). Photo by Bill Hubick. (MBP list)

Cedar Apple Rust (winter gall) on Eastern Red Cedar in Calvert Co., Maryland (3/18/2017). Photo by Bill Hubick. (MBP list)

Overwintering Cedar Apple Rust gall in Howard Co., Maryland (2/3/2012). Photo by Robert Solem. (MBP list)

A Cedar Apple Rust gall in Worcester Co., Maryland (3/25/2017). Photo by Ashley Bradford. (MBP list)

Cedar Apple Rust (overwintering gall) in Montgomery Co., Maryland (11/22/2014). Photo by Jane Hill. (MBP list)

Cedar Apple Rust in Baltimore Co., Maryland (4/24/2020). (c) travels2see, some rights reserved (CC BY-NC). Photo by travels2see via iNaturalist. (MBP list)

Cedar Apple Rust in Anne Arundel Co., Maryland (10/10/2020). (c) Matthew Beziat, some rights reserved (CC BY-NC). Photo by Matthew Beziat via iNaturalist. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (5/13/2018). (c) Matthew Moskwik, some rights reserved (CC BY-NC). Photo by Matthew Moskwik via iNaturalist. (MBP list)

Cedar Apple Rust in Worcester Co., Maryland (11/22/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (5/17/2015). (c) Mike Ostrowski, some rights reserved (CC BY-SA). Photo by Mike Ostrowski. (MBP list)

Cedar Apple Rust in Charles Co., Maryland (4/10/2019). (c) Tim Emhoff, some rights reserved (CC BY-NC). Photo by Tim Emhoff via iNaturalist. (MBP list)

Cedar Apple Rust in Charles Co., Maryland (3/13/2020). (c) Tim Emhoff, some rights reserved (CC BY-NC). Photo by Tim Emhoff via iNaturalist. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (3/16/2020). (c) mmn_noriko, some rights reserved (CC BY-NC). Photo by mmn_noriko via iNaturalist. (MBP list)

Cedar Apple Rust in Allegany Co., Maryland (4/14/2018). (c) jrcagle, some rights reserved (CC BY-NC). Photo by jrcagle via iNaturalist. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (11/18/2017). (c) lynnparsons, some rights reserved (CC BY-NC). Photo by lynnparsons via iNaturalist. (MBP list)

Cedar Apple Rust in Howard Co., Maryland (3/27/2020). (c) Bonnie Ott, some rights reserved (CC BY-NC). Photo by Bonnie Ott via iNaturalist. (MBP list)

Cedar Apple Rust in Anne Arundel Co., Maryland (4/27/2018). (c) whimsicalgrimm, some rights reserved (CC BY-NC). Photo by whimsicalgrimm via iNaturalist. (MBP list)

Cedar Apple Rust in Caroline Co., Maryland (3/13/2020). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (4/13/2019). (c) Kristof Zyskowski, some rights reserved (CC BY-NC-ND). Photo by Kristof Zyskowski via iNaturalist. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (4/14/2010). (c) Hans Holbrook, some rights reserved (CC BY-NC). Photo by Hans Holbrook. (MBP list)

Cedar Apple Rust in Howard Co., Maryland (2/25/2018). (c) Timothy Reichard, all rights reserved. Photo by Timothy Reichard. (MBP list)

Cedar Apple Rust in Charles Co., Maryland (4/25/2020). (c) Tim Emhoff, some rights reserved (CC BY-NC). Photo by Tim Emhoff via iNaturalist. (MBP list)

Cedar Apple Rust in Baltimore Co., Maryland (4/24/2020). (c) Peter M Martin, some rights reserved (CC BY-NC). Photo by Peter M Martin via iNaturalist. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (4/13/2019). (c) Jenny Glenn, some rights reserved (CC BY-NC). Photo by Jenny Glenn via iNaturalist. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (5/1/2020). (c) Lauren, some rights reserved (CC BY-NC). Photo by Lauren via iNaturalist. (MBP list)

Cedar Apple Rust in Prince George's Co., Maryland (5/1/2019). (c) blites, some rights reserved (CC BY-NC). Photo by blites via iNaturalist. (MBP list)

Cedar Apple Rust aeciospores collected in Howard Co., Maryland (8/7/2016). Thick-walled, 5- to 7-sided, brown; measured 21.1-25.4 X 18.3-20.5 microns. Photo by Robert Solem. (MBP list)

Cedar Apple Rust in Talbot Co., Maryland (3/10/2013). (c) botanygirl, some rights reserved (CC BY). Photo by botanygirl via iNaturalist. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (3/25/2017). (c) Matt Muir, some rights reserved (CC BY-SA). Photo by Matt Muir via iNaturalist. (MBP list)

Cedar Apple Rust in Howard Co., Maryland (3/11/2017). (c) Timothy Reichard, all rights reserved. Photo by Timothy Reichard. (MBP list)

Cedar Apple Rust in Montgomery Co., Maryland (3/25/2017). (c) Matt Muir, some rights reserved (CC BY-SA). Photo by Matt Muir via iNaturalist. (MBP list)

Cedar Apple Rust in Carroll Co., Maryland (12/20/2019). (c) Emilio Concari, some rights reserved (CC BY-NC). Photo by Emilio Concari. (MBP list)

Cedar Apple Rust in Worcester Co., Maryland (3/25/2018). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Cedar Apple Rust in Charles Co., Maryland (3/8/2020). (c) hkig, some rights reserved (CC BY-NC). Photo by hkig via iNaturalist. (MBP list)


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