| Cypress canker | |
|---|---|
 Asexual fructifications of cypress canker disease | |
| Causal agents | Seiridium spp. |
| Hosts | Cypress trees |
| Distribution | Europe, North America, Australia, New Zealand |
Cypress canker is a disease affecting Cupressus species, caused by one of several species of fungus in the genus Seiridium . Infection causes die-back of twigs and branches in susceptible cypress trees, [1] with rapidly increasing amounts of damage and the death of the tree.
The first epidemic of cypress canker was recorded in California in 1928, with Monterey cypress (Cupressus macrocarpa) being affected. Within a few years the local populations of this tree had been killed. The species is widely traded as an ornamental tree and the disease had soon spread worldwide, probably with nursery stock. Within five decades the disease had reached New Zealand, France, Chile, Italy, Argentina, Greece, most of Europe, Canada, North Africa, South Africa and Australia. The causal agent of this pandemic spread was the pathogenic fungus Seiridium cardinale , with Seiridium cupressi and Seiridium unicorne sometimes being involved, but being less aggressive; other pathogenic fungi can also cause cankers in cypresses. [2]
Besides Monterey cypress, other trees attacked by the fungi that cause this canker include Cupressus sempervirens , Cupressus pygmaea , Cupressus lusitanica , Platycladus orientalis , Chamaecyparis lawsoniana , Calocedrus decurrens , Juniperus chinensis and Juniperus sabina . Even when a species is susceptible, environmental factors are important in the development of the disease. In California, for example, Monterey cypresses growing on the coastal ranges were found to be much less affected than those growing in inland areas where the climate was of a Mediterranean type. [3]
The fungal spores gain entry into the tree through natural fissures or through injuries to the bark. The growth of the fungal thalli interferes with the phloem tissue of the host tree, cutting off the flow of sap and eventually killing the branch above the wound. The foliage turns yellow and the branch rapidly dies. A sunken canker with a reddish tinge develops at the original site of infection and resin often oozes out nearby. Each canker is long and narrow and there may be several on one branch. Black circular sporing structures later appear alongside the canker. [4]
The disease can be spread between trees by rain splashes, small animals, birds or insects. [4] The spores can gain entry through the stomata and lenticels under optimal conditions and conidia can get washed down branches by water trickles to lodge as new infective sites. The fungus can remain viable in dead tissue for several years. Vectors include bark beetles in the genus Phloeosinus , [2] and the cypress aphid (Cinara cupressi). [5]
The pathogenic fungus Cryphonectria parasitica is a member of the Ascomycota. This necrotrophic fungus is native to East Asia and South East Asia and was introduced into Europe and North America in the early 1900s. The fungus spread rapidly and caused significant tree loss in both regions.
Hesperocyparis macrocarpa also known as Cupressus macrocarpa, or the Monterey cypress is a coniferous tree, and is one of several species of cypress trees endemic to California.
The Leyland cypress, Cupressus × leylandii, X Cuprocyparis leylandii or X Cupressocyparis leylandii, often referred to simply as leylandii, is a fast-growing coniferous evergreen tree much used in horticulture, primarily for hedges and screens. Even on sites of relatively poor culture, plants have been known to grow to heights of 15 metres (49 ft) in 16 years. Their rapid, thick growth means they are sometimes used to achieve privacy, but such use can result in disputes with neighbours whose own property becomes overshadowed. The tree is a hybrid of Monterey cypress and Nootka cypress. It is almost always sterile, and is propagated mainly by cuttings.
Alternaria alternata is a fungus causing leaf spots, rots, and blights on many plant parts, and other diseases. It is an opportunistic pathogen on over 380 host species of plant.
Nectria cinnabarina, also known as coral spot, is a plant pathogen that causes cankers on broadleaf trees. This disease is polycyclic and infects trees in the cool temperate regions of the Northern Hemisphere. N. cinnabarina is typically saprophytic, but will act as a weak parasite if presented with an opportunity via wounds in the tree or other stressors that weaken the tree's defense to the disease. A study published in 2011 showed that this complex consists of at least 4 distinct species. There are only a few ways to manage this disease with techniques such as sanitation and pruning away branches that have the cankers. N. cinnabarina is not as significant a problem as other Nectria spp., some of which are the most important pathogens to infect hardwood trees.
Ophiostoma novo-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the key causative agents associated with Dutch Elm Disease (DED), along with Ophiostoma ulmi and Ophiostoma himal-ulmi.
Botryosphaeria stevensii is a fungal plant pathogen that causes cankers on several tree species including apple and juniper as well as causing cankers on grape vines. It causes branch dieback, possibly affecting a large portion of the tree canopy, and if severe it can kill entire plants.
Lepteutypa cupressi is a plant pathogen which causes a disease in Cupressus, Thuja, and related conifer types.
The plant pathogenic fungus Leucostoma kunzei is the causal agent of Leucostoma canker, a disease of spruce trees found in the Northern Hemisphere, predominantly on Norway spruce and Colorado blue spruce. This disease is one of the most common and detrimental stem diseases of Picea species in the northeastern United States, yet it also affects other coniferous species. Rarely does it kill its host tree; however, the disease does disfigure by killing host branches and causing resin exudation from perennial lesions on branches or trunks.
Eutypella canker is a plant disease caused by the fungal pathogen Eutypella parasitica. This disease is capable of infecting many species of maple trees and produces a large, distinguishable canker on the main trunk of the tree. Infection and spread of the disease is accomplished with the release of ascospores from perithecia. Therefore, the best way to manage the Eutypella canker is to remove trees that have been infected. If infected, it can decrease the quality of wood cut for lumber and can thus have a negative economic impact.
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.
Lepteutypa is a genus of plant pathogens in the family Amphisphaeriaceae. First described by the Austrian mycologist Franz Petrak in 1923, the genus contains 10 species according to a 2008 estimate. It was increased to 15 in 2020.
Thousand cankers disease (TCD) is a recently recognized disease of certain walnuts. The disease results from the combined activity of the walnut twig beetle and a canker producing fungus, Geosmithia morbida. Until July 2010 the disease was only known to the western United States where over the past decade it has been involved in several large scale die-offs of walnut, particularly black walnut, Juglans nigra. However, in late July 2010 a well-established outbreak of the disease was found in the Knoxville, Tennessee, area. This new finding is the first locating it within the native range of its susceptible host, black walnut. In 2013, an outbreak was found in the Veneto region of Italy, where the disease has been found on both black walnut and English walnut.
Cinara cupressi, the cypress aphid, is a brownish soft-bodied aphid. It sucks sap from twigs of conifers, and can cause damage to the tree, ranging from discoloring of the affected twig to the death of the tree. This insect appears to have originated in the Middle East and has been increasing its range and is considered to be an invasive species in Africa and Europe. It has been included in the List of the world's 100 worst invasive species.
Seiridium is a genus of plant pathogens in the family Sporocadaceae.
Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs. The most common hosts of the pathogen include slash pine, loblolly pine, Monterey pine, Mexican weeping pine, and Douglas fir. Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.
The foamy bark canker is a disease affecting oak trees in California caused by the fungus Geosmithia sp. #41 and spread by the Western oak bark beetle. This disease is only seen through the symbiosis of the bark beetles and the fungal pathogen. The bark beetles target oak trees and bore holes through the peridermal tissues, making tunnels within the phloem. The fungal spores are brought into these tunnels by the beetles and begin to colonize the damaged cells inside the tunnels. Symptoms of the developing fungus include wet discoloration seeping from the beetle entry holes as the fungus begins to consume phloem and likely other tissues. If bark is removed, necrosis of the phloem can be observed surrounding the entry hole(s). As the disease progresses, a reddish sap and foamy liquid oozes from entry holes, thus giving the disease the name foamy bark canker. Eventually, after the disease has progressed, the tree dies. This disease is important because of its detrimental effects on oak trees and its ability to spread to several new Californian counties in just a couple of years.
Hypoxylon canker of shade trees is a weak ascomycete fungus that negatively affects growth and can eventually lead to the death of already dying or diseased host trees. There are many different species that affect different trees. For example, Hypoxylon atropunctatum, a common species, is found on oak trees, Hypoxylon tinctor affects sycamore trees, and Hypoxylon mammatum infests aspen trees.
Seiridium cardinale is a species of fungus within the genus of Seiridium, in the Sporocadaceae family.
Gnomoniopsis castaneae is a fungus of the order Diaporthales that is the most important cause of brown chestnut rot, an emerging disease that damages the fruit of chestnuts. It also causes cankers and necrosis on leaves and on chestnut galls caused by the gall wasp, Dryocosmus kuriphilus. Additionally, it can cause cankers on other chestnut species, red oak, hazelnut trees, less severe damage to some nut trees, and lives as an endophyte on other nut trees. The disease has been reported in Europe, Oceania, and has recently been found in North America; for this reason, the fungus is considered a potential threat to the reintroduction of the American chestnut.