Gymnosporangium Totally Explained

Everything about Gymnosporangium totally explained

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).
   In junipers (the primary hosts) (see photo), the fungus forms a ball 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. 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 doesn't 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.

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	(not known)
Gymnosporangium nidus-avis	Juniperus sect. Sabina	Crataegus, Cydonia, Malus
Gymnosporangium torminalis-juniperinum	Juniperus sect. Juniperus	Sorbus torminalis
Gymnosporangium tremelloides	Juniperus sect. Juniperus	Cydonia, Malus, Sorbus
Gymnosporangium yamadae	Juniperus	Malus

References and external links

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.
Penn State Extension Gymnosporangium Fact Sheet
Forestry Images: Gymnosporangium
Canadian Food Inspection Agency Factsheet: Gymnosporangium yamadae
Photo of Gymnosporangium sabinae on Juniperus sabina
Photo of Gymnosporangium juniperi-virginianae on an apple leaf

Further Information

Get more info on 'Gymnosporangium'.

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