| Gymnosporangium globosum | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Pucciniomycetes |
| Order: | Pucciniales |
| Family: | Gymnosporangiaceae |
| Genus: | Gymnosporangium |
| Species: | G. globosum |
| Binomial name | |
| Gymnosporangium globosum (Farl.) Farl. | |
Gymnosporangium globosum is a fungal plant pathogen that causes cedar-hawthorn rust.
Gymnosporangium globosum is a heteroecious rust fungus that requires two hosts to complete its life cycle. Its telial stage occurs on eastern red cedar, Rocky Mountain juniper, southern red cedar, and other common junipers while its aecial stage will be found on apple, crabapple, hawthorne, and occasionally on pear, quince, and serviceberry. The symptoms on the evergreens (telial stage) start with small galls that form on its twigs and small branches. After the galls grow to be 1⁄8 to 1⁄2 inch in diameter, circular indents (similar to those of a golf ball) will begin to appear on the twig side of the gall. Once spring arrives, a reddish-brown structure will begin to grow out of the indent eventually producing orange, jelly-like telial horns. These telial horns can reach up to 4 inches long and can be easily seen. The symptoms of the deciduous trees (aecial stage) begin with yellow spots that progress into orange-red as the season continues. Black dots (spermagonia) will then develop in the center of the lesion. Mature lesions will then produce small tubes (aecia). These lesions can be found on leaves, petioles, twigs, and fruit. The aecia are approximately ⅛ inch long. [1] [2]
The fungus begins its cycle overwintering in the galls of its telial host. During early spring, the telial horns form on the evergreen host, which produces teliospores that germinate creating a basidium. The basidium then produces basidiospores, which are released via wind and rain to infect its aecial, deciduous host's plant tissues (leaves, twigs, fruit, petioles). 80–90 days after the basidiospores germinate, aecia are produced that create aeciospores. The aeciospores are released into the air by the combination of wind and low humidity and infect susceptible evergreen hosts from midsummer into early fall beginning its telial stage. The fungus then survives as hyphae in the evergreen over that winter and begins to produce a gall the following spring. The gall increases in size throughout the summer and fall seasons so it can overwinter the spore bearing structures that will protrude out the following spring thus restarting the cycle. Thus, the entire life cycle of this rust takes 24 months to complete. [3] [4]
The cedar-hawthorne rust is common all across the Midwest and Eastern United States. Its overwintering capability allows it to thrive in seasonal climates with harsh winters. The pathogen prefers humid and cloudy conditions for developing growth and the spores depend on rain and wind to be dispersed to its alternate host. Requiring two separate hosts to complete its life cycle is a limiting factor on where it can grow as both hosts must be present within a 1–2 mile radius. [5] [6]
There are a variety of ways to attempt to prevent this pathogen from spreading. The first being to prune out any infected branches of either host species. The second is to avoid planting two host plants within a two-mile radius of each other. This does not guarantee safety as there have been cases reported of cedar-hawthorne rust spores traveling 15 miles to infect its complementary host. There are also a multitude of different hawthorne varieties that have been bred for resistance, so choosing one of those is wise if a known susceptible evergreen host is growing nearby. Resorting to fungicide application is also an option. It is found to be most effective when applied during the spore producing period of its life cycle. If all else fails, both hosts can live with G. globosum without dying for decades as the pathogen is rarely lethal. [7] [8]
Many of the susceptible hosts are common ornamental landscaping shrubs and trees which add importance to this pathogen. Although cedar-hawthorne rust typically does not kill either of the host plants, it can cause atypical growth and present unattractive symptoms on the leaves, stems, and fruit of the plants. Apples are not the preferred deciduous host for Gymnosporangium globosum but it can decimate apple orchards. A closely related rust, Gymnosporangium juniperi-virginianae , causes cedar-apple rust and is the more common rust that affects apple yields and is a consistent difficulty for apple growers. [9]
Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast.
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. The common name cedar-apple rusts has been used for these fungi. According to the Dictionary of the Fungi, there was 57 species in the genus. In 2023, Species Fungorum lists up to 74 species.
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 hosts are required for the parasite to complete its life cycle. This can be contrasted with an autoecious parasite which can complete its life cycle on a single host species. Many rust fungi have heteroecious life cycles:
Rusts are fungal plant pathogens of the order Pucciniales causing plant fungal diseases.
Cronartium ribicola is a species of rust fungus in the family Cronartiaceae that causes the disease white pine blister rust. Other names include: Rouille vésiculeuse du pin blanc (French), white pine Blasenrost (German), moho ampolla del pino blanco (Spanish).
Teliospore is the thick-walled resting spore of some fungi, from which the basidium arises.
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 eastern red cedar or a number of other juniper species to complete its life cycle.
Gymnosporangium juniperi-virginianae is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples (Malus) and eastern red cedar coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars. Apples, crabapples, and eastern red cedar are the most common hosts for this disease. Similar diseases can be found on quince and hawthorn and many species of juniper can substitute for the eastern red cedars.
Puccinia asparagi is the causative agent of asparagus rust. It is an autoecious fungus, meaning that all stages of its life cycle – pycniospores, aeciospores, and teliospores – all develop upon the same host plant . Rust diseases are among the most destructive plant diseases, known to cause famine following destruction of grains, vegetables, and legumes. Asparagus rust occurs wherever the plant is grown and attacks asparagus plants during and after the cutting season. Asparagus spears are usually harvested before extensive rust symptoms appear. Symptoms are first noticeable on the growing shoots in early summer as light green, oval lesions, followed by tan blister spots and black, protruding blisters later in the season. The lesions are symptoms of Puccinia asparagi during early spring, mid-summer and later summer to fall, respectively. Severe rust infections stunt or kill young asparagus shoots, causing foliage to fall prematurely, and reduce the ability of the plant to store food reserves. The Puccinia asparagi fungus accomplishes this by rust lowering the amounts of root storage metabolites. The infected plant has reduced plant vigor and yield, often leading to death in severe cases. Most rust diseases have several stages, some of which may occur on different hosts; however, in asparagus rust all the life stages occur on asparagus. Because of this, many observers mistake the different stages of the Puccinia asparagi life cycle as the presence of different diseases. The effects of Puccinia asparagi are present worldwide wherever asparagus is being grown. Asparagus rust is a serious threat to the asparagus industry.
Puccinia helianthi is a macrocyclic and autoecious fungal plant pathogen that causes rust on sunflower. It is also known as "common rust" and "red rust" of sunflower.
Puccinia menthae is a fungal plant pathogen that causes rust on mint plants. It was originally found on the leaves of Mentha aquatica.
Uromyces viciae-fabae var. viciae-fabae is a plant pathogen commonly known as faba-bean rust. The rust is distinguished by the typical rust-like marks on the stem and leaves, causing defoliation and loss of photosynthetic surface along with reduction in yield. The disease is fungal and is autoecious meaning it has one plant host. The rust of faba beans is macrocyclic, or contains 5 spores during its life cycle.
Gymnosporangium sabinae is a species of rust fungus in the subdivision Pucciniomycotina. Known as pear rust, European pear rust, or pear trellis rust, it is a heteroecious plant pathogen with Juniperus sabina as the main primary (telial) host and Pyrus communis as the main secondary (aecial) host.
Puccinia monoica is a parasitic rust fungus of the genus Puccinia that inhibits flowering in its host plant and radically transforms host morphology in order to facilitate its own sexual reproduction.
Telium, plural telia, are structures produced by rust fungi as part of the reproductive cycle. They are typically yellow or orange drying to brown or black and are exclusively a mechanism for the release of teliospores which are released by wind or water to infect the alternate host in the rust life-cycle. The telial stage provides an overwintering strategy in the life cycle of a parasitic heteroecious fungus by producing teliospores; this occurs on cedar trees. A primary aecial stage is spent parasitizing a separate host plant which is a precursor in the life cycle of heteroecious fungi. Teliospores are released from the telia in the spring. The spores can spread many kilometers through the air, however most are spread near the host plant.
Gymnosporangium clavariiforme is a species of rust fungus which alternately infects Juniperus and hawthorns.
Pine-pine gall rust, also known as western gall rust, is a fungal disease of pine trees. It is caused by Endocronartium harknessii, an autoecious, endocyclic, rust fungus that grows in the vascular cambium of the host. The disease is found on pine trees with two or three needles, such as ponderosa pine, jack pine and scots pine. It is very similar to pine-oak gall rust, but its second host is another Pinus species. The fungal infection results in gall formation on branches or trunks of infected hosts. Gall formation is typically not detrimental to old trees, but has been known to kill younger, less stable saplings. Galls can vary from small growths on branch extremities to grapefruit-sized galls on trunks.
Spruce broom rust or yellow witches' broom rust is a fungal plant disease caused by the basidiomycete fungus known as Chrysomyxa arctostaphyli. It occurs exclusively in North America, with the most concentrated outbreaks occurring in northern Arizona and southern Colorado on blue and Engelmann spruce, as well as in Alaska on black and white spruce. This disease alternates its life cycle between two hosts, with the spruce serving as the primary host and bearberry serving as the secondary or alternate host. The name for the disease comes from the distinctive “witches broom”, commonly yellow in color, which forms on the spruce after young needles have been infected. Management must be carried out through physical or mechanical methods, such as the pruning of brooms or the removal of the secondary host from the area, because no chemical control measures have yet been determined to be economically effective. Generally, spruce broom rust is seen as a mostly cosmetic issue, and it is very rarely the direct cause of tree death; however, research has shown a reduction in overall productivity and health of infected trees, making it an important issue for logging and timber companies.
Phakopsora euvitis is a rust fungus that causes disease of grape leaves. This rust fungus has been seen in regions including: Eastern Asia, Southern Asia, Southwestern Brazil, the Americas, and northern Australia. It is widely distributed in eastern and southern Asia but was first discovered on grapevines in Darwin, Australia in 2001 and was identified as Asian grapevine leaf rust by July 2007.
Cronartium quercuum, also known as pine-oak gall rust is a fungal disease of pine and oak trees. Similar to pine-pine gall rust, this disease is found on pine trees but its second host is an oak tree rather than another pine.