Phytophthora cinnamomi

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Phytophthora cinnamomi
Phytophthora cinnamomi under microscope.png
A: seven-day-old colony on PARP medium; B: sporangia; C: gametangia; D: oospore.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Oomycota
Order: Peronosporales
Family: Peronosporaceae
Genus: Phytophthora
Species:
P. cinnamomi
Binomial name
Phytophthora cinnamomi
Varieties

Phytophthora cinnamomi, also known as cinnamon fungus, is a soil-borne water mould [1] that produces an infection which causes a condition in plants variously called "dieback", "root rot", or (in certain Castanea species), "ink disease".

Contents

Once infected soil or water is introduced, the organism can spread rapidly throughout an environment. An infestation can lead to the illness, death, and possible eradication of vulnerable plants, as well as habitat reduction for animals. An outbreak can be challenging to recognize and can inflict irreversible harm to ecosystems. [1]

The plant pathogen is one of the world's most invasive species and is present in over 70 countries around the world.

Distribution and hosts

Phytophythora cinnamomi is distributed worldwide and can infect a diverse range of hosts, including club mosses, ferns, cycads, conifers, cord rushes, grasses, lilies and a large number of species from many dicotyledonous families, and is included in the Invasive Species Specialist Group list of "100 of the World's Worst Invasive Alien Species". [2] Its potential range is expected to extend northward with warming due to climate change. [3]

It affects a range of economic plants, including food crops such as avocado and pineapple; as well as trees and woody ornamentals such as Fraser firs, shortleaf pines, loblolly pines, azaleas, camellia and boxwood, causing root rot, dieback and death of infected plants. [4] Symptoms include wilting, decreased fruit size and yield, collar rot, gum exudation, necrosis, leaf chlorosis, leaf curl, and stem cankers. [5] It can also cause dieback of young shoots and may interfere with transpiration of roots to shoots. Older plants may not display symptoms or only exhibit mild dieback despite having severe root rot. [6]

Reproduction

Phytophthora cinnamomi is a diploid and primarily heterothallic species with two mating types, A1 and A2. [7] Sexual reproduction in heterothallic Phytophthora species ordinarily occurs when gametangia of opposite mating type interact in host tissue. This interaction leads to the formation of oospores that can survive for long periods in or outside the host. Phytophthora cinnamomi is facultatively homothallic and capable of self-fertilization. Cultures of mating type A2 can be induced to undergo sexual reproduction by damaging conditions such as exposure to hydrogen peroxide or mechanical damage. [8]

Life cycle

Phytophthora cinnamomi lives in the soil and in plant tissues and can spread in water. [9] During periods of harsh environmental conditions, the organisms become dormant chlamydospores. When environmental conditions are suitable, the chlamydospores germinate, producing mycelia (or hyphae) and sporangia. The sporangia ripen and release zoospores, which infect plant roots by entering the root behind the root tip. Zoospores need water to move through the soil, therefore infection is most likely in moist soils. After entering the root, mycelia grow throughout the root absorbing carbohydrates and nutrients and destroy the structure of the root tissues, "rotting" the root and preventing the plant from absorbing water and nutrients. Sporangia and chlamydospores form on the mycelia of the infected root allowing further dispersal.

Transmission

A heath landscape in the Stirling Range, Western Australia, with a dieback-infested valley in the mid ground Die back valley gnangarra.jpg
A heath landscape in the Stirling Range, Western Australia, with a dieback-infested valley in the mid ground

Although P. cinnamomi was first identified in tropical and subtropical countries, but can survive and develop in cooler climates as well. [10] It spreads as zoospores and/or chlamydospores in soil and water under favourable conditions such as warm temperatures and high soil moisture.

Methods of transmission include local invasion via contact between the roots of infected and susceptible plants, downslope movement in surface or subsurface water such as rivers or irrigation water, zoospore dispersal over long distances via wind-blown soil and debris, and transport of infected plant matter and soil, for example via particles stuck to footwear, vehicles or equipment. [4] [5] [11] Native and feral animals have been known to transport the disease, including through the digestive tract of feral pigs. [4] However human activities such as timber harvesting, mining, bush walking, and road construction are also major methods of dispersal. [10]

Environmental impacts

Littleleaf disease in Pinus spp. The tree on the left shows no symptoms of infection while the tree on the right shows stunted leaf growth characteristic of Phytophthora cinnamomi infection. Littleleaf disease.jpg
Littleleaf disease in Pinus spp. The tree on the left shows no symptoms of infection while the tree on the right shows stunted leaf growth characteristic of Phytophthora cinnamomi infection.

When Phytophthora dieback spreads to native plant communities, it kills many susceptible plants, resulting in a permanent decline in the biodiversity and a disruption of ecosystem processes. [1] It can also change the composition of the forest or native plant community by increasing the number of resistant plants and reducing the number of susceptible plant species. Native animals that rely on susceptible plants for survival are reduced in numbers or are eliminated from sites infested by Phytophthora dieback. [12]

Australia

In Australia, where it is known as phytophthora dieback, dieback, jarrah dieback or cinnamon fungus, Phytophthora cinnamomi can infect thousands of native plants, causing damage to forests and removing habitats for wildlife. [12] [13] [14] Several native plants are at risk of extinction due to the effects of the disease. [12]

Phytophthora cinnamomi's impact is greatest in Western Australia, Victoria, Tasmania and South Australia, while the Northern Territory remains unaffected due to the unfavourability of the environment. [12]

Of particular concern is the infection and dieback of large areas of forest and heathland which support threatened species in the south-west Western Australia. Many plants from the genera Banksia , Darwinia , Grevillea , Leucopogon , Verticordia and Xanthorrhoea are susceptible. This in turn impacts on animals reliant on these plants for food and shelter, such as the southwestern pygmy possum (Cercartetus concinnus) and the honey possum (Tarsipes rostratus). A study in the Perth region found that dieback caused a significant shift in the bird community and affected nectar-feeding species the most, with fewer species such as the Western Spinebill in areas that were dieback-infested. [15]

U.S. and Mexico

Damage to forests suspected to be caused by Phytophthora cinnamomi was first recorded in the United States about 200 years ago. Infection can cause littleleaf disease of shortleaf pine (Pinus echinata), Christmas tree disease in nursery grown Fraser fir (Abies fraseri), and sudden death of a number of native tree species such as American chestnut. Oak populations are affected in areas ranging from South Carolina to Texas.

Phytophthora cinnamomi is also a problem in the Mexican state of Colima, killing several native oak species and other susceptible vegetation in the surrounding woodlands. It is implicated in the die-off of the rare endemic shrub Ione manzanita (Arctostaphylos myrtifolia) in California. [16]

Commercial effects

Phytophthora cinnamomi is the leading cause of damage to avocado trees, and is commonly known as "root rot" amongst avocado farmers. Since the 1940s various breeds of root rot-resistant avocados have been developed to minimize tree damage. Damaged trees generally die or become unproductive within three to five years. A 1960 study of the Fallbrook, California, area correlated higher levels of avocado root rot to soils with poorer drainage and greater clay content. [17]

Control

Warning sign near Mount Dale, Western Australia advising to keep vehicles out of dieback affected areas to prevent the spread of this fungus. Dieback sign gnangarra.jpg
Warning sign near Mount Dale, Western Australia advising to keep vehicles out of dieback affected areas to prevent the spread of this fungus.
A boot cleaning station in Lesueur National Park designed to limit the spread of dieback Boot cleaning station in Lesueur National Park, September 2023.jpg
A boot cleaning station in Lesueur National Park designed to limit the spread of dieback

No treatment has been found to eradicate P. cinnamomi, although an integrated approach can control the spread and impact of the disease.

Gardening practices to restrict spread include restricting soil or water movement from infected areas by using clean bins and equipment, installing watertight drains to prevent surface run off, and working last in diseased areas after harvesting healthy areas first. [18]

Planting in raised beds promotes rapid drainage and reduces prolonged contact of plant roots with water, making the soil environment less hospitable to P. cinnamomi. [6] For specific plants such as young avocado plants, soil solarisation by using clear polythene sheets laid on the soil surface to trap radiant heat from the sun can reduce spread, and an integrated approach is generally taken to control disease on avocado. [4]

Chemical means of control include fumigation and the use of phosphonate fungistats. [19] Fumigation prior to planting may be effective on some life stages of P. cinnamomi, but does not eliminate chlamydospores as they are present deeper in the soil where fumigation may not reach. [6] However, fumigation can potentially worsen disease by reducing the population of competing soil microorganisms, and P. cinnamomi is often able to re-invade fumigated soil.

Phosphonate fungistats can improve the ability of a tree to tolerate, resist, or recover from infection. Phosphite administered through direct foliage sprays, aerial application by aircraft or direct injection has been used to limit the disease with some success and has been recognized as a major strategy for disease prevention. [18]

Commonly potassium phosphite is used as a biodegradable fungicide,[ dubious – discuss ] and calcium or magnesium phosphite may also be used. Overuse of phosphate may harm the treated plant, especially when the plant is phosphate deficient. [20]

See also

Related Research Articles

<i>Phytophthora</i> Genus of single-celled organisms

Phytophthora is a genus of plant-damaging oomycetes, whose member species are capable of causing enormous economic losses on crops worldwide, as well as environmental damage in natural ecosystems. The cell wall of Phytophthora is made up of cellulose. The genus was first described by Heinrich Anton de Bary in 1875. Approximately 210 species have been described, although 100–500 undiscovered Phytophthora species are estimated to exist.

<span class="mw-page-title-main">Fusarium wilt</span> Fungal plant disease

Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.

The ecology of Banksia is the relationships and interactions among the plant genus Banksia and its environment. Banksia has a number of adaptations that have so far enabled the genus to survive despite dry, nutrient-poor soil, low rates of seed set, high rates of seed predation and low rates of seedling survival. These adaptations include proteoid roots and lignotubers; specialised floral structures that attract nectariferous animals and ensure effective pollen transfer; and the release of seed in response to bushfire.

Root rot is a condition in which anoxic conditions in the soil or potting media around the roots of a plant cause them to rot. This occurs due to excessive standing water around the roots. It is found in both indoor and outdoor plants, although it is more common in indoor plants due to overwatering, heavy potting media, or containers with poor drainage. The leaves of plants experiencing root rot often yellow and die, and if allowed to continue, the condition can be fatal.

Phytophthora sojae is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate, and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.

<i>Phytophthora palmivora</i> Species of single-celled organism

Phytophthora palmivora is an oomycete that causes bud-rot of palms, fruit-rot or kole-roga of coconut and areca nut. These are among the most serious diseases caused by fungi and moulds in South India. It occurs almost every year in Malnad, Mysore, North & South Kanara, Malabar and other areas. Similar diseases of palms are also known to occur in Sri Lanka, Mauritius, and Sumatra. The causative organism was first identified as P. palmivora by Edwin John Butler in 1917.

<i>Phytophthora cactorum</i> Species of single-celled organism

Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.

<i>Phytophthora medicaginis</i> Species of single-celled organism

Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and chickpea. It is a major disease of these plants and is found wherever they are grown. P. medicaginis causes failure of stand establishment because of seedling death. Phytophthora medicaginis is part of a species complex with Phytophthora megasperma.

Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.

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<i>Phytophthora capsici</i> Species of single-celled organism

Phytophthora capsici is an oomycete plant pathogen that causes blight and fruit rot of peppers and other important commercial crops. It was first described by L. Leonian at the New Mexico State University Agricultural Experiment Station in Las Cruces in 1922 on a crop of chili peppers. In 1967, a study by M. M. Satour and E. E. Butler found 45 species of cultivated plants and weeds susceptible to P. capsici In Greek, Phytophthora capsici means "plant destroyer of capsicums". P. capsici has a wide range of hosts including members of the families Solanaceae and Cucurbitaceae as well as Fabaceae.

Phytophthora fragariae is a fungus-like (oomycete) plant pathogen that causes red stele, otherwise known as Lanarkshire disease, in strawberries. Symptoms of red stele can include a red core in the roots, wilting of leaves, reduced flowering, stunting, and bitter fruit. The pathogen is spread via zoospores swimming through water present in the soil, released from sporangia.

Phytophthora megakarya is an oomycete plant pathogen that causes black pod disease in cocoa trees in west and central Africa. This pathogen can cause detrimental loss of yield in the economically important cocoa industry, worth approximately $70 billion annually. It can damage any part of the tree, causing total yield losses which can easily reach 20-25%. A mixture of chemical and cultural controls, as well as choosing resistant plant varieties, are often necessary to control this pathogen.

<i>Phytophthora kernoviae</i> Species of oomycete

Phytophthora kernoviae is a plant pathogen that mainly infects European beech and Rhododendron ponticum. It was first identified in 2003 in Cornwall, UK when scientists were surveying for the presence of Phytophthora ramorum. This made it the third new Phytophthora species to be found in the UK in a decade. It was named Phytophthora kernoviae after the ancient name for Cornwall, Kernow. It causes large stem lesions on beech and necrosis of stems and leaves of Rhododendron ponticum. It is self-fertile. It has also been isolated from Quercus robur and Liriodendron tulipifera. The original paper describing the species, stated it can infect Magnolia and Camellia species, Pieris formosa, Gevuina avellana, Michelia doltsopa and Quercus ilex. Since then many other plants have been identified as natural hosts of the pathogen. Molecular analysis has revealed that an infection on Pinus radiata, recorded in New Zealand in 1950, was caused by P. kernoviae. The pathogen was also noted on Drimys winteri, Gevuina avellana, Ilex aquifolium, Quercus ilex, Vaccinium myrtillus, Hedera helix, Podocarpus salignas.

<i>Phytophthora plurivora</i> Species of single-celled organism

Phytophthora plurivora is a very aggressive soil-borne plant pathogen, with worldwide distribution and a wide variety of hosts.

<span class="mw-page-title-main">Kauri dieback</span> Species of oomycete

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Buckeye rot of tomato is caused by three species of pathogens in the genus Phytophthora: P. nicotianae var. parasitica, P. capsici, and P. drechsleri. It is an oomycete that thrives in warm, wet conditions and lives in the soil. It is characterized by a bull’s eye pattern of dark brown rotting on the tomato fruit, and affects fruit that is close to, or lying on the soil. The easiest management is to keep the plant out of contact with the soil, although other chemical methods can be very effective. This disease commonly occurs in the southeast and south central areas of the United States. The disease has affected a large portion of crop yield in the United States as well as India. The relatively small genome size of Phytophthora parasitica compared to Phytophthora infestans gives researchers the unique ability to further examine its ability to cause disease.

Black rot on orchids is caused by Pythium and Phytophthora species. Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids.

Cranberry Root Rot (CRR) is a disease in cranberries that can cause a decline in yield.

References

  1. 1 2 3 "Phytophthora dieback". Australian Government - Department of Climate Change, Energy, the Environment and Water. 3 October 2021. Retrieved 11 April 2023.
  2. ↑ "100 of the World's Worst Invasive Alien Species". Invasive Species Specialist Group. Retrieved 6 June 2019.
  3. ↑ Gustafson, Eric J.; Miranda, Brian R.; Dreaden, Tyler J.; Pinchot, Cornelia C.; Jacobs, Douglass F. (February 2022). "Beyond blight: Phytophthora root rot under climate change limits populations of reintroduced American chestnut". Ecosphere. 13 (2). doi:10.1002/ecs2.3917.
  4. 1 2 3 4 "Data Sheets on Quarantine Pests: Phytophthora cinnamomi" (PDF). EPPO and CABI.[ permanent dead link ]
  5. 1 2 "Phytophthora cinnamomi (Phytophthora dieback)". CABI.
  6. 1 2 3 Reuter, Courtney. "Phytophthora cinnamomi Rands". NCSU. Archived from the original on 2020-05-13. Retrieved 2017-12-12.
  7. ↑ Linde C, Drenth A, Kemp GH, Wingfield MJ, von Broembsen SL (August 1997). "Population Structure of Phytophthora cinnamomi in South Africa". Phytopathology. 87 (8): 822–7. doi:10.1094/PHYTO.1997.87.8.822. PMID   18945050.
  8. ↑ Reeves, RJ; Jackson, RM (October 1974). "Stimulation of Sexual Reproduction in Phytophthora by Damage". Journal of General Microbiology. 84 (2): 303–310. doi: 10.1099/00221287-84-2-303 .
  9. ↑ Managing Phytophthora Dieback in Bushland: A Guide for Landholders and Community Conservation Groups (PDF) (5th ed.). Australia: Dieback Working Group. 2009. ISBN   9780646493046. Archived from the original (PDF) on 2014-03-06. Retrieved 2013-09-17.
  10. 1 2 Robin, C.; Smith, I.; Hansen, E. M. (2012-12-28). "Phytophthora cinnamomi". Forest Phytophthoras. 2 (1). doi:10.5399/osu/fp.2.1.3041. ISSN   2164-7232.
  11. ↑ Cahill, David M. (2008). "TURNER REVIEW No. 17. Phytophthora cinnamomi and Australia's biodiversity: impacts, predictions and progress towards control". Australian Journal of Botany. 56 (4): 279. doi:10.1071/bt07159.
  12. 1 2 3 4 "Arrive Clean, Leave Clean" (PDF). environment.gov.au. April 12, 2023. p. 4. Retrieved April 12, 2023.
  13. ↑ Cinnamon Fungus. Parks Victoria. parkweb.vic.gov.au
  14. ↑ Groves, E.; Hollick, P.; Hardy, G.; McComb, J. "WA list of susceptible plants" (PDF). Murdoch University.
  15. ↑ Davis, Robert A.; Valentine, Leonie E.; Craig, Michael D.; Wilson, Barbara; Bancroft, Wesley J.; Mallie, Marnie (March 2014). "Impact of Phytophthora-dieback on birds in Banksia woodlands in south west Western Australia" (PDF). Biological Conservation. 171: 136–144. doi:10.1016/j.biocon.2014.01.027.
  16. ↑ Swiecki, T. J.; Bernhardt, E. A. (2003). "Diseases threaten the survival of Ione manzanita (Arctostaphylos myrtifolia)". Phytosphere Research.
  17. ↑ Burns, R. M.; Miner, J. H.; Gustafson, C. D.; Zentmyer, G. A.; Thorn, W. A. (1960). "Correlation of soil series and avocado root rot damage in the Fallbrook area" (PDF). Yearbook. Vol. 44. California Avocado Society. pp. 110–113.
  18. 1 2 Cahill, David M.; Rookes, James E.; Wilson, Barbara A.; Gibson, Lesley; McDougall, Keith L. (2008-07-07). "Phytophthora cinnamomi and Australia's biodiversity: impacts, predictions and progress towards control". Australian Journal of Botany. 56 (4): 279–310. doi:10.1071/bt07159. ISSN   1444-9862.
  19. ↑ "Avocado Phytophthora Root Rot". UC IPM. Archived from the original on 2018-01-29. Retrieved 2017-12-12.
  20. ↑ Thao; Yamakawa (2008). "Phosphite (phosphorous acid): Fungicide, fertilizer or bio-stimulator?". Soil Science and Plant Nutrition. 55 (2): 228–234. doi: 10.1111/j.1747-0765.2009.00365.x . S2CID   95723306.
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