Gymnosporangium
Encyclopedia
Gymnosporangium is a genus
of heteroecious
plant-pathogenic
fungi
which alternately infect members of the family Cupressaceae
, primarily species in the genus Juniperus (juniper
s), and members of the family Rosaceae
in the subfamily Maloideae
(apple
s, pear
s, quince
s, shadbush, hawthorns
, rowan
s and their relatives). According to the Dictionary of the Fungi (10th edition, 2008), there are about 57 species in the genus.
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 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 orchard
s are of commercial importance, some regions have attempted to ban the planting of and/or eradicate the coniferous hosts.
Selected species
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of heteroecious
Heteroecious
A heteroecious parasite is one that requires at least two hosts. The primary host is the host in which the parasite spends its adult life; the other is the secondary host. Both the primary host and an unrelated alternate host are required for the parasite to complete its life cycle...
plant-pathogenic
Phytopathology
Plant pathology is the scientific study of plant diseases caused by pathogens and environmental conditions . Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants...
fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
which alternately infect members of the family Cupressaceae
Cupressaceae
The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
, primarily species in the genus Juniperus (juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
s), and members of the family Rosaceae
Rosaceae
Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...
in the subfamily Maloideae
Maloideae
The Maloideae C.Weber are the apple subfamily, a grouping used by some taxonomists within the rose family, Rosaceae. Recent molecular phylogenetic evidence has shown that the traditional Spiraeoideae and Amygdaloideae form part of the same clade as the traditional Maloideae, and the correct name...
(apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s, pear
Pear
The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
s, quince
Quince
The quince , or Cydonia oblonga, is the sole member of the genus Cydonia and native to warm-temperate southwest Asia in the Caucasus region...
s, shadbush, hawthorns
Crataegus
Crataegus , commonly called hawthorn or thornapple, is a large genus of shrubs and trees in the rose family, Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe,...
, rowan
Rowan
The rowans or mountain-ashes are shrubs or small trees in genus Sorbus of family Rosaceae. They are native throughout the cool temperate regions of the Northern Hemisphere, with the highest species diversity in the mountains of western China and the Himalaya, where numerous apomictic microspecies...
s and their relatives). According to the Dictionary of the Fungi (10th edition, 2008), there are about 57 species in the genus.
In junipers (the primary hosts) (see photo), some species of the fungus form a ball like gall
Gall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
about 2–4 cm in diameter which produces a set of orange tentacle-like spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
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 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 orchard
Orchard
An orchard is an intentional planting of trees or shrubs that is maintained for food production. Orchards comprise fruit or nut-producing trees which are grown for commercial production. Orchards are also sometimes a feature of large gardens, where they serve an aesthetic as well as a productive...
s 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 Gymnosporangium clavariiforme thumb|left|Close up of G. clavariforme telia on Juniperus communisGymnosporangium clavariiforme is a species of rust fungus which alternately infects Juniperus and hawthorns.... |
Juniperus sect. Juniperus | Amelanchier, Crataegus, Pyrus |
| Gymnosporangium clavipes Gymnosporangium clavipes Gymnosporangium clavipes is a plant pathogen, a fungus that causes cedar-quince rust. Similar to Gymnosporangium juniperi-virginianae and Gymnosporangium globosum, the fungus infects a wide range of Rosaceae, such as apple, hawthorn, and quince trees, and also requires an evergreen host such as... |
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 Gymnosporangium fuscum Gymnosporangium sabinae is a fungal heteroecious plant pathogen with Juniperus as the primary host and Pyrus , Malus , or Crataegus as secondary hosts... (syn. G. sabinae) |
Juniperus sect. Sabina | Pyrus |
| Gymnosporangium fusisporum | Juniperus sect. Sabina | Cotoneaster |
| Gymnosporangium gaeumannii | Juniperus communis | (not known) |
| Gymnosporangium globosum Gymnosporangium globosum Gymnosporangium globosum is a plant pathogen that causes cedar-hawthorn rust.- External links :... |
Juniperus | Crataegus |
| Gymnosporangium gracile | Juniperus | Amelanchier, Crataegus, Cydonia |
| Gymnosporangium harknessianum | Juniperus | Amelanchier |
| Gymnosporangium inconspicuum | Juniperus | Amelanchier |
| Gymnosporangium juniperi-virginianae Gymnosporangium juniperi-virginianae Gymnosporangium juniperi-virginianae is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples and Eastern red cedar coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars... |
Juniperus | Malus |
| Gymnosporangium kernianum Gymnosporangium kernianum Gymnosporangium kernianum is a plant pathogen.- External links :* *... |
Juniperus | Amelanchier |
| Gymnosporangium libocedri Gymnosporangium libocedri Gymnosporangium libocedri is a plant pathogen.- External links :**... |
Calocedrus | Amelanchier |
| Gymnosporangium malyi | (not known) | Crataegus |
| Gymnosporangium multiporum | Juniperus | (not known) |
| Gymnosporangium nelsonii Gymnosporangium nelsonii Gymnosporangium nelsonii is a plant pathogen.- External links :* *... |
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 Gymnosporangium yamadae Gymnosporangium yamadae is a plant pathogen.- External links :... |
Juniperus | Malus |
External links
- Penn State Extension Gymnosporangium Fact Sheet
- Forestry Images: Gymnosporangium
- Photo of Gymnosporangium sabinae on Juniperus sabinaJuniperus sabinaJuniperus sabina is a species of juniper native to the mountains of central and southern Europe and western and central Asia, from Spain east to eastern Siberia, typically growing at altitudes of 1,000-3,300 m....
