Fusarium circinatum

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Fusarium circinatum
Pine pitch canker.jpg
Pitch canker affecting western white pine
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Nectriaceae
Genus: Fusarium
Species:
F. circinatum
Binomial name
Fusarium circinatum
Nirenberg & O'Donnell
Synonyms
  • Fusarium subglutinans f. sp. pini
  • Fusarium lateritium f. sp. pini

Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs ( Pseudotsuga menziesii ). The most common hosts of the pathogen include slash pine ( Pinus elliottii ), loblolly pine ( Pinus taeda ), Monterey pine ( Pinus radiata ), Mexican weeping pine ( Pinus patula ), and Douglas fir. [1] Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.

Contents

Distribution

This fungus is believed to have originated in Mexico. It spread to the eastern United States in 1946 and by 1986 had reached the western United States. It was first recorded in Japan in the 1980s, in South Africa in 1990, in Chile [2] and Spain in the mid 1990s and in Italy in 2007. [3]

Host species

In California this canker has been recorded on nine different species of pine ( Pinus ) and on Douglas fir ( Pseudotsuga menziesii ). [3] In Europe and Asia it has been recorded on over 30 other Pinus species. [4] Monterey pine ( Pinus radiata ) seems to be the most susceptible species, and in California 85% of the native Monterey pine forests were initially thought to be threatened by the disease. [5] Because of the activation of systemic acquired resistance in native Monterey pine trees, however, the impacts of the disease in California have been mitigated. [6]

Biology

Fusarium circinatum infects the twigs and branches of pine trees, causing a bark canker. Most infection is by macroconidia or microconidia. The macroconidia are 3-septate, with slightly curved walls and the microconidia are single-celled, ovoid, and borne in false heads on aerial polyphialides. The aerial mycelium is white or pale violet colour and slightly twisted below the proliferation of microconidiophores. In culture, perithecia are readily produced. They are dark purple or black and ovoid. [7] Cylindrical asci are released by oozing. There are eight ascospores which are 1-septate and ellipsoidal to fusiform. Because peritheca have not been observed in the field, it is not thought that ascospores are an important route for infection. [4]

The infection is usually carried from tree to tree by the rain, the wind or by bark-feeding insects. These including weevils in the genus Pityophthorus and bark beetles in the genera Ips and Conophthorus. These insects commonly infect pine trees and the adults may disperse the pathogen. Additionally, these insects cause a wound when feeding and this may facilitate entry of the infection. [8] Warmth and moisture encourage the development of the disease whereas cooler drier conditions restrict it. In California it is more severe in coastal areas. [9]

Research was undertaken to see whether spores from the teleomorph, Gibberella circinata, might be responsible for spread of the fungus. It was found that very few vegetative compatibility groups existed among the California strains of the pathogen. This implied that asexual reproduction predominated and laboratory tests confirmed this.[ citation needed ]

Hyperparasites

Unusually for mycoviruses, Muñoz-Adalia et al., 2016 finds that both Fusarium circinatum mycovirus 1 (FcMV1) and Fusarium circinatum mycovirus 2 (FcMV2) increase the virulence of F. circinatum. This has been observed to produce increased disease severity on P. radiata. [10]

Symptoms

The various symptoms of F. circinatum can help identify and distinguish it from other pathogens or common Pinus diseases. The symptoms are similar to other damping off diseases with seedlings wilting and dying and exuding resin from the root collar areas. [2] Drooping from the resin production and the plant’s resistance mechanism can be observed along with die-back near the apical meristem. A discoloration of the stem and needles is usually present, with plants exhibiting purple or blue shades. [11] Other symptoms include chlorosis of the needles turning a reddish brown color and lesions on the stems, root collars, and tap roots. [12] Host factors that can trigger infection include plant stress with excessive nitrogen in the soil, unbalanced watering cycles, warmer temperatures, and wounds from pruning or insect damage. [11]

Spread

Numerous plant pathologists have noted F. circinatum as a serious threat to the pine tree species. Due to the high tree mortality rate, reduced growth, and degradation of wood quality, the economic and ecological importance are greatly affected by this disease. Not only can the spread of infection go from branch to branch, but also infect pine seeds, leading to damping-off of younger seedlings and resulting in death from the fungal infection. [13] The environmental interactions that take place to favor the spread and development of this disease play a large role in transmission. Factors such as soil nutrient ratio, abiotic stressors, air pollution, temperature, and humidity can all contribute to the spread of this disease. [14]

In Chile, the infection was first reported on Pinus radiata in nurseries and was thought to be due to the import of contaminated seed. Seedlings could also be infected by soil-borne contamination. A few years later, the disease had not spread to mature stands of trees. [2] The same is true in South Africa, where it was reported to infect nursery stock but not forest trees. [15]

Fusarium circinatum is spread locally by wind and insects, but it is slow to spread into new areas. Over large distances it can be transported in contaminated pine seeds or by young plants. Although it could be carried as infected timber, this is considered unlikely especially if the bark has been removed. If timber had been a significant means of infection, the fungus would have spread more rapidly to other parts of the world as there is a considerable trade in pine. [4]

The vectors for this disease, such as insects, rely on whether or not the species is indigenous to where the pine is located. There are also different ranges of susceptibility that can interact within the environment. Bishop pine (Pinus muricata ) has a more extensive range of susceptibility compared to Monterey pine, which serves as a “host bridge” to more northern locations for susceptible Pinus species. [16]

Management

Several strategies are currently being used to help decrease the spread of F. circinatum. Irrigation water can be chemically treated with a chlorination system or ozone treatment. Following corrected pH levels in water, it is recommended that 2-3 ppm of chlorine be administered. Proper hygiene practices and surface sterilization are to be maintained throughout management, especially by preventing the accumulation of water nearby to deter increases in insect populations. The use of insecticides can reduce the number of vectors present that typically allow the infection to occur. Within pine nurseries, it is common for the dying seedlings to be removed and saturated with a fungicide. A single, systematic fungicide should not be used continuously as resistance can develop. [12]

While pitch canker can cause damage to the pine industry, some cases of infection recover. Susceptible Monterey pine trees that were repeatedly exposed to the pathogen gained resistance over time under controlled conditions, especially where the disease has been present for over 10 years. Removing diseased trees from areas as a conservative approach allows for the possibility of recovery. [17]

Testing

A test has been developed for detecting contamination of seeds of Pinus species by F. circinatum. It is based on the biological enrichment of a sample followed by a real-time polymerase chain reaction assay. Many countries are imposing quarantine controls on movement of propagating materials and this test can help prevent the introduction of the pathogen through contaminated seed. [18]

See also

Notes

The epithet refers to the diagnostic coiled hyphae that are produced by this species. [19]

Related Research Articles

<i>Pinus radiata</i> Species of conifer

Pinus radiata, the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast of California and Mexico. It is an evergreen conifer in the family Pinaceae.

<i>Pinus elliottii</i> Species of conifer tree

Pinus elliottii, commonly known as slash pine, is a conifer tree native to the Southeastern United States. Slash pine is named after the "slashes" – swampy ground overgrown with trees and bushes – that constitute its habitat. Other common names include swamp pine, yellow slash pine, and southern Florida pine. Slash pine has two different varieties: P. e. var. elliottii and P. e. var. densa. Historically, slash pine has been an important economic timber for naval stores, turpentine, and resin. The wood of slash pine is known for its unusually high strength, especially for a pine. It exceeds many hardwoods and is even comparable to very dense woods such as ironwood.

<span class="mw-page-title-main">Canker</span> Common name for a tree disease

A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticulture. Their causes include a wide range of organisms as fungi, bacteria, mycoplasmas and viruses. The majority of canker-causing organisms are bound to a unique host species or genus, but a few will attack other plants. Weather and animal damage can also cause stress to the plant resulting in cankers. Other causes of cankers is pruning when the bark is wet or using un-sterilized tools.

<i>Cronartium ribicola</i> Species of rust fungus

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).

<span class="mw-page-title-main">Scleroderris canker</span> Species of fungus

Scleroderris canker, or Brunchorstia disease, Gremmeniella abietina, is a species of fungal diseases infecting coniferous forests. The main symptom is the death of the needles, leading to the death of the tree. In the forest industry, fighting off an infection of Scleroderris canker is usually not cost-effective. Clearing is often preferred over fungicidal methods, as the latter is harmful to other living organisms.

<span class="mw-page-title-main">Diplodia tip blight</span> Fungal disease of conifers

Diplodia tip blight, also known as Sphaeropsis blight, is a widespread disease affecting conifers caused by an opportunistic fungal pathogen, Diplodia sapinea. It is found in “both hemispheres between the latitudes 30° and 50° north and south". The diseases symptoms include: damping off and collar rot of seedlings, stem canker, root disease, and, most commonly, shoot blight. These symptoms have caused significant economic loss to nurseries and pine plantations. In a nursery in the north-central United States, losses of 35% have been reported. Shoot blight and eventual die back can cause a reduction of marketable volume in timber by 63%. Infection of terminal shoots can result in dead-top which significantly limits the usable length of the tree trunk. The presence of the pathogen in concert with severe weather conditions can lead to extreme loss. Following a severe hailstorm in South Africa, nearly 5,000 acres of pine plantation were infected with Diplodia tip blight. It was necessary to prematurely harvest large swaths of the plantations resulting in a loss of 45%. Areas that were not harvested prematurely still suffered an average timber loss of 11%.

<i>Alternaria alternata</i> Pathogenic fungus

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.

<i>Nectria cinnabarina</i> Fungal plant pathogen

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.

<i>Gibberella zeae</i> Species of fungus

Gibberella zeae, also known by the name of its anamorph Fusarium graminearum, is a fungal plant pathogen which causes fusarium head blight (FHB), a devastating disease on wheat and barley. The pathogen is responsible for billions of dollars in economic losses worldwide each year. Infection causes shifts in the amino acid composition of wheat, resulting in shriveled kernels and contaminating the remaining grain with mycotoxins, mainly deoxynivalenol (DON), which inhibits protein biosynthesis; and zearalenone, an estrogenic mycotoxin. These toxins cause vomiting, liver damage, and reproductive defects in livestock, and are harmful to humans through contaminated food. Despite great efforts to find resistance genes against F. graminearum, no completely resistant variety is currently available. Research on the biology of F. graminearum is directed towards gaining insight into more details about the infection process and reveal weak spots in the life cycle of this pathogen to develop fungicides that can protect wheat from scab infection.

Gibberella xylarioides is a species of fungus in the family Nectriaceae. It is the causative agent of coffee wilt disease (CWD). The disease caused a severe problem in several countries in West and East Africa during the 1940s and 1950s. CWD was first seen in Coffea liberica.

<i>Fusarium subglutinans</i> Species of fungus

Fusarium subglutinans is a fungal plant pathogen.

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.

<i>Gibberella fujikuroi</i> Species of fungus

Gibberella fujikuroi is a fungal plant pathogen. It causes bakanae disease in rice seedlings.

<span class="mw-page-title-main">Swanton Pacific Ranch</span>

Swanton Pacific Ranch is a 3,200-acre (1,300 ha) ranch in Santa Cruz County, California, outside the town of Davenport. The ranch is owned and operated by California Polytechnic State University for educational and research in sustainable agriculture. The ranch encompasses rangeland, livestock, and forestry operations for the College of Agriculture, Food and Environmental Sciences, comprises a significant part of the community of Swanton, and includes the lower Scott Creek watershed.

<span class="mw-page-title-main">Monterey County reforestation</span>

The Monterey County reforestation refers to efforts in Monterey County, California, to preserve the county's pine forests and urban environment. This one county boasts the native Monterey Pine ecosystem; one of the rarest forest ecosystems in the world. Only a few thousand acres of these endemic trees exist in four locations along the Pacific Ocean on the Central Coast of California. The city of Monterey itself maintains more than 19,000 trees in parks and along streets, as well as about 300 acres (1.2 km2) of Monterey Pine forests.

<span class="mw-page-title-main">Wilt disease</span> Group of plant diseases

A wilt disease is any number of diseases that affect the vascular system of plants. Attacks by fungi, bacteria, and nematodes can cause rapid killing of plants, large tree branches or even entire trees.

<span class="mw-page-title-main">Pine-pine gall rust</span> Fungal disease of pine trees

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.

<span class="mw-page-title-main">Hypoxylon canker of shade trees</span> Tree disease

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.

<span class="mw-page-title-main">Cypress canker</span> Plant fungal disease

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, with rapidly increasing amounts of damage and the death of the tree.

Coffee wilt disease (tracheomycosis) is a common wilt that results in complete death of coffee trees it infects. This vascular disease is induced by the fungal pathogen known by its teleomorph Gibberella xylarioides. In 1927, coffee wilt disease (CWD) was first observed in the Central African Republic where it developed slowly and went on to cause two epidemics between the 1930s and the 1960s. Coffee wilt disease was first seen in Coffea excelsa.

References

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