Gymnosporangium
| Gymnosporangium | |
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| A Gymnosporangium species | |
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| Genus: | Gymnosporangium |
| Type species | |
| Gymnosporangium fuscum DC. (1805)
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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 Maloideae (apples, pears, quinces, shadbush, hawthorns, rowans and their relatives). According to the Dictionary of the Fungi (10th edition, 2008), there are about 57 species in the genus.[1]
In junipers (the primary hosts) (see photo), some species of the fungus 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 the telia are produced directly from the bark of the juniper with no obvious gall formation or swelling[2] such as in G. clarvariforme . The spores are released and travel on the wind until they infect an apple, pear, or hawthorn 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. The spores must then infect a juniper to complete the life cycle.
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. 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.[3]
- Selected species
| Species | Primary host | Secondary host |
|---|---|---|
| Gymnosporangium amelanchieris | Juniperus sect. Juniperus | Amelanchier |
| Gymnosporangium clavariiforme | Juniperus sect. Juniperus | Amelanchier, Crataegus, Pyrus |
| Gymnosporangium clavipes | Juniperus | Cydonia |
| Gymnosporangium confusum | Juniperus | Crataegus, Cydonia, Mespilus, Pyrus |
| Gymnosporangium cornutum | Juniperus sect. Juniperus | Sorbus subgen. Sorbus |
| Gymnosporangium cupressi | Cupressus | Amelanchier |
| Gymnosporangium dobroznakovii | Juniperus sect. Juniperus | Pyrus |
| Gymnosporangium fuscum (syn. G. sabinae) | Juniperus sect. Sabina | Pyrus |
| Gymnosporangium fusisporum | Juniperus sect. Sabina | Cotoneaster |
| Gymnosporangium gaeumannii | Juniperus communis | (not known) |
| Gymnosporangium globosum | Juniperus | Crataegus |
| Gymnosporangium gracile | Juniperus | Amelanchier, Crataegus, Cydonia |
| Gymnosporangium harknessianum | Juniperus | Amelanchier |
| Gymnosporangium inconspicuum | Juniperus | Amelanchier |
| Gymnosporangium juniperi-virginianae | Juniperus | Malus |
| Gymnosporangium kernianum | Juniperus | Amelanchier |
| Gymnosporangium libocedri | Calocedrus | Amelanchier |
| Gymnosporangium malyi | (not known) | Crataegus |
| Gymnosporangium multiporum | Juniperus | (not known) |
| Gymnosporangium nelsonii | Juniperus | Amelanchier |
| Gymnosporangium nidus-avis | Juniperus sect. Sabina | Crataegus, Cydonia, Malus |
| Gymnosporangium sabinae | Juniperus | Pyrus, Malus, Crataegus |
| Gymnosporangium torminalis-juniperinum | Juniperus sect. Juniperus | Sorbus torminalis |
| Gymnosporangium tremelloides | Juniperus sect. Juniperus | Cydonia, Malus, Sorbus |
| Gymnosporangium yamadae | Juniperus | Malus |
References
- ^ Kirk PM, Cannon PF, Minter DW, Stalpers JA. (2008). Dictionary of the Fungi (10th ed.). Wallingford, UK: CABI. p. 298. ISBN 978-0-85199-826-8.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Brand, Bert; Brand, Gill; Shattock, Richard (2006). "Sorting out Gymnosporangium species – the aecial stage". Field Mycology. 7 (4): 123–127. doi:10.1016/S1468-1641(10)60574-9.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Cedar Apple Rust - Plant of the Week
- 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.
