Gymnosporangium: Difference between revisions

Latest revision as of 13:42, 5 January 2024

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Gymnosporangium is a genus of heteroecious plant-pathogenic fungi which alternately infect members of the family Cupressaceae, primarily species in the genus Juniperus (junipers), and members of the family Rosaceae in the subfamily Amygdaloideae (apples, pears, quinces, shadbush, hawthorns, rowans and their relatives). The common name cedar-apple rusts has been used for these fungi.<ref name="Kern1973">Template:Cite book</ref> According to the Dictionary of the Fungi (10th edition, 2008), there was 57 species in the genus.<ref name=Kirk2008/> In 2023, Species Fungorum lists up to 74 species.<ref name=Fungorum/>

In junipers (the primary hosts, see photo), some species form a ball-like gall about 2–4 cm in diameter which produces a set of orange tentacle-like spore tubes called telial horns. These horns expand and have a jelly like consistency when wet. In other species, such as in G. clarvariforme, the telia are produced directly from the bark of the juniper with no obvious gall formation or swelling.<ref>Template:Cite journal</ref> The basidiospores are released and travel on the wind until they infect an apple, pear, hawthorn or suitable tree.

On the secondary hosts, the fungus produces yellowish depressions on the leaves. It also infects the fruit, which grows whitish tubes like a Medusa head. These are the spore tubes. These aeciospores must then infect a juniper to complete the life cycle. All the types of spores can spread over long distances.<ref name="EPPO_2006" />

The fungus does not cause serious damage to junipers, but apple and pear trees can suffer serious loss of fruit production due to the effects of the fungus. Although the genus has a worldwide distribution, its impact depends on availability of its two host plant species. Individual species are found in Northern and Central America, Asia, Europe and the Middle East.<ref name="EPPO_2006">Template:Cite journal</ref>

Due to the economic impacts of the rusts in some areas where orchards are of commercial importance, some regions have attempted to ban the planting of and/or eradicate the coniferous hosts.<ref>Template:Cite web</ref>

In 2020, the monotypic family Gymnosporangiaceae was proposed to accommodate Gymnosporangium.<ref>Template:Cite journal</ref> As accepted by Wijayawardene et al. 2020.<ref name="Wijayawardene et al. 2020">Template:Cite journal</ref>

Selected species and hosts

Species	Primary host	Secondary host	Common name
Gymnosporangium amelanchieris	Juniperus sect. Juniperus	Amelanchier
Gymnosporangium clavariiforme	Juniperus sect. Juniperus	Amelanchier, Crataegus, Pyrus	Tongues of Fire<ref>Gymnosporangium cornutum/clavariforme, Scottish Fungi</ref>
Gymnosporangium clavipes	Juniperus	Crataegus, Cydonia	Cedar-quince rust, quince rust<ref name=US/>
Gymnosporangium confusum	Juniperus	Crataegus, Cydonia, Mespilus, Pyrus
Gymnosporangium cornutum	Juniperus sect. Juniperus	Sorbus subgen. Sorbus	Mountain ash juniper rust<ref name=US>FullFungi List, Widely Prevalent Fungi of the United States</ref>
Gymnosporangium cupressi	Cupressus	Amelanchier
Gymnosporangium dobroznakovii	Juniperus sect. Juniperus	Pyrus
Gymnosporangium fusisporum	Juniperus sect. Sabina	Cotoneaster
Gymnosporangium gaeumannii	Juniperus communis	(not known)
Gymnosporangium globosum	Juniperus	Crataegus	Cedar-hawthorn rust, American hawthorn rust<ref name=US/><ref name=APS/>
Gymnosporangium gracile	Juniperus	Amelanchier, Crataegus, Cydonia
Gymnosporangium harknessianum	Juniperus	Amelanchier
Gymnosporangium inconspicuum	Juniperus	Amelanchier
Gymnosporangium juniperi-virginianae	Juniperus	Malus	Cedar-apple rust<ref name=US/>
Gymnosporangium kernianum	Juniperus	Amelanchier	Kern's pear rust<ref name=APS>Diseases of Pear, APS</ref>
Gymnosporangium libocedri (Now Gymnotelium blasdaleanum, Pucciniaceae family)	Calocedrus	Amelanchier	Pacific Coast pear rust,<ref name=APS/> Incense cedar broom rust<ref name=US/>
Gymnosporangium malyi	(not known)	Crataegus
Gymnosporangium multiporum	Juniperus	(not known)
Gymnosporangium nelsonii	Juniperus	Amelanchier	Witches broom rust,<ref name=US/> Rocky Mountain pear<ref name=APS/>
Gymnosporangium nidus-avis	Juniperus sect. Sabina	Crataegus, Cydonia, Malus	Juniper witches' broom rust<ref name=US/>
Gymnosporangium sabinae	Juniperus	Pyrus, Malus, Crataegus	Pear rust, European pear rust, or pear trellis rust<ref name=US/>
Gymnosporangium torminalis-juniperinum	Juniperus sect. Juniperus	Sorbus torminalis
Gymnosporangium tremelloides	Juniperus sect. Juniperus	Cydonia, Malus, Sorbus
Gymnosporangium yamadae	Juniperus	Malus	Japanese apple rust<ref>Gymnosporangium yamadae Template:Webarchive, Data sheets on Quaranteen Pests</ref>

Full list of species

As accepted by Species Fungorum;<ref name=Fungorum/> Template:Div col

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References

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Other sources

Phillips, D.H., & Burdekin, D.A. (1992). Diseases of Forest and Ornamental Trees. Macmillan.
Scharpf, R.F., ed. (1993). Diseases of Pacific Coast Conifers. USDA Forest Service Agricultural Handbook 521.

External links

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