Plant disease

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(Redirected from
Plant pathogen
)
For the journal, see Plant Disease (journal).
Life cycle of the black rot pathogen, the gram negative bacterium Xanthomonas campestris pathovar campestris

Plant diseases are diseases in

plant tissues and causing injury that may admit plant pathogens. The study of plant disease is called plant pathology
.

Plant pathogens

Further information: Lists of plant diseases

Fungi

Powdery mildew, a biotrophic Ascomycete fungus

Most phytopathogenic fungi are

saprotrophically, carrying out the part of their life cycle in the soil
. These are facultative saprotrophs.

Fungal diseases may be controlled through the use of

fungicides and other agriculture practices. However, new races of fungi often evolve
that are resistant to various fungicides.

Biotrophic fungal pathogens colonize living plant tissue and obtain nutrients from living host cells.

Necrotrophic fungal pathogens infect and kill host tissue and extract nutrients from the dead host cells.[3]

Significant fungal plant pathogens include:

Ascomycetes

Basidiomycetes

Puccinia tricicina

Fungus-like organisms

Oomycetes

The

sudden oak death.[11][12]

Despite not being closely related to the fungi, the oomycetes have developed similar infection strategies, using effector proteins to turn off a plant's defenses.[13]

Phytomyxea

Some

Spongospora, respectively.[14]

Bacteria

Crown gall disease caused by Agrobacterium

Most

tropical regions of the world.[15][page needed
]

Most plant pathogenic bacteria are bacilli. Erwinia uses cell wall–degrading enzymes to cause soft rot. Agrobacterium changes the level of auxins to cause tumours with phytohormones.

Significant bacterial plant pathogens include:

Mollicutes

Vitis vinifera with "Ca. Phytoplasma vitis" infection

psyllids, both sap-sucking insect vectors. These inject the bacteria into the plant's phloem, where it reproduces.[19]

Tobacco mosaic virus

Viruses

Main article: Plant virus

Many plant viruses cause only a loss of

perennial species, such as fruit trees.[citation needed
]

Most plant viruses have small, single-stranded

plasmodesmata, and sometimes a protein that allows transmission by a vector.[citation needed
]

Plant viruses are generally transmitted by a

vector, but mechanical and seed transmission also occur. Vectors are often insects such as aphids; others are fungi, nematodes, and protozoa. In many cases, the insect and virus are specific for virus transmission such as the beet leafhopper that transmits the curly top virus causing disease in several crop plants.[20]

Nematodes

Main article: Nematode
Root-knot nematode galls

Some

subtropical regions. Potato cyst nematodes (Globodera pallida and G. rostochiensis) are widely distributed in Europe and the Americas, causing $300 million worth of damage in Europe annually. Root knot nematodes have quite a large host range, they parasitize plant root systems and thus directly affect the uptake of water and nutrients needed for normal plant growth and reproduction,[21] whereas cyst nematodes tend to be able to infect only a few species. Nematodes are able to cause radical changes in root cells in order to facilitate their lifestyle.[22]

Protozoa

A few plant diseases are caused by

viruses. When the motile zoospores come into contact with a root hair they produce a plasmodium which invades the roots.[citation needed
]

Physiological plant disorders

Main article: Physiological plant disorder

Some abiotic disorders can be confused with pathogen-induced disorders. Abiotic causes include natural processes such as drought, frost, snow and hail; flooding and poor drainage; nutrient deficiency; deposition of mineral salts such as sodium chloride and gypsum; windburn and breakage by storms; and wildfires. [24]

Orchid leaves with viral infections

Epidemics

Plants are subject to disease epidemics.

Port and border inspection and quarantine

The introduction of harmful nonnative organisms into a country van be reduced by controlling human traffic (e.g., the Australian Quarantine and Inspection Service). Global trade provides unprecedented opportunities for the introduction of plant pests.[McC 1] In the United States, even to get a better estimate of the number of such introductions would require a substantial increase in inspections.[McC 2] In Australia a similar shortcoming of understanding has a different origin: Port inspections are not very useful because inspectors know too little about taxonomy. There are often pests that the Australian Government has prioritised as harmful to be kept out of the country, but which have near taxonomic relatives that confuse the issue.[BH 1]

X-ray and electron-beam/E-beam irradiation of food has been trialed as a quarantine treatment for fruit commodities originating from Hawaii. The US FDA (Food and Drug Administration), USDA APHIS (Animal and Plant Health Inspection Service), producers, and consumers were all accepting of the results - more thorough pest eradication and lesser taste degradation than heat treatment.[25]

The

less developed countries unless funding changes.[26]

Chemical

See also: Pesticide application

Many natural and synthetic compounds can be employed to combat plant diseases. This method works by directly eliminating disease-causing organisms or curbing their spread; however, it has been shown to have too broad an effect, typically, to be good for the local ecosystem. From an economic standpoint, all but the simplest natural additives may disqualify a product from "organic" status, potentially reducing the value of the yield.

Biological

Crop rotation is a traditional and sometimes effective means of preventing pests and diseases from becoming well-established, alongside other benefits.[27]

Other biological methods include inoculation. Protection against infection by

Agrobacterium radiobacter before inserting them in the ground to take root.[28]

Economic impact

Plant diseases cause major economic losses for farmers worldwide. Across large regions and many crop species, it is estimated that diseases typically reduce plant yields by 10% every year in more developed settings, but yield loss to diseases often exceeds 20% in less developed settings. The Food and Agriculture Organization estimates that pests and diseases are responsible for about 25% of crop loss. To solve this, new methods are needed to detect diseases and pests early, such as novel sensors that detect plant odours and spectroscopy and biophotonics that are able to diagnose plant health and metabolism.[29]

As of 2018 the most costly diseases of the most produced crops worldwide are:[30]

Crop Disease Latin name Disease common name
Banana and plantain banana bunchy top virus (BBTV) banana bunchy top
Mycosphaerella fijiensis
 black sigatoka
Fusarium oxysporum f.sp. cubense
 Panama disease
Barley
Fusarium graminearum
Fusarium head blight
Blumeria graminis f. sp. hordei
 powdery mildew
Puccinia graminis f. sp. hordei barley stem rust
Cassava African cassava mosaic virus (ACMVD) African cassava mosaic disease
Xanthomonas axonopodis pv. manihotis
 bacterial blight
cassava brown streak virus (CBSV) cassava brown streak disease
Cotton Xanthomonas citri pv. malvacearum bacterial blight
Fusarium oxysporum f. sp. vasinfectum
 Fusarium wilt
Verticillium dahliae Verticillium wilt
Maize/corn Aspergillus flavus Aspergillus ear rot
Fusarium graminearum
 Giberella stalk and ear rot
Cercospora zeae-maydis
grey leaf spot
Palm fruit
 Ganoderma orbiforme/Ganoderma boninense
Basal stem rot
Phytophthora palmivora bud rot
Peanut groundnut rosette virus (GNV) Groundnut rosette disease
GNV satellite RNA
groundnut rosette assistor virus (GRAV)
Potato Ralstonia solanacearum Potato brown rot
Phytophthora infestans
late blight
Rapeseed and mustard Leptosphaeria maculans Phoma stem canker
Sclerotinia sclerotiorum
Sclerotinia stem rot
Rice
Magnaporthe oryzae
rice blast
Xanthomonas oryzae pv. oryzae rice bacterial blight
Rhizoctonia solani
sheath blight
Sorghum and millet Colletotrichum sublineolum
Anthracnose
Exserohilum turcicum
Turcicum leaf blight
Soybean
Heterodera glycines
 soybean cyst nematode disease
Phakopsora pachyrhizi
Asian soybean rust
Sugar beet Cercospora beticola
Cercospora leaf spot
beet necrotic yellow vein virus (BNYVV)
rhizomania
Sugarcane Leifsonia xyli subsp. xyli Ratoon stunting
Colletotrichum falcatum
 red rot
Sweet potato sweet potato feathery mottle virus (SPFMV) sweet potato virus disease (SPVD)
sweet potato chlorotic stunt virus (SPCSV)
Tomato Phytophthora infestans late blight
tomato yellow leaf curl virus (TYLCV) tomato yellow leaf curl
Wheat
Fusarium graminearum
Fusarium head blight
Puccinia graminis
wheat stem rust
Puccinia striiformis
 wheat yellow rust
Yam
Colletotrichum gloeosporioides
 anthracnose
yam mosaic virus (YMV) yam mosaic disease

See also

Notes

  1. ^ p. 17, "It is clear, however, that continuing increases in global trade and travel will provide opportunities for nonindigenous species to be transported into the U.S. at rates that are unprecedented in world history."
  2. ^ p. 17, " A more comprehensive estimate of the frequency and diversity of nonindigenous plants, particularly those introduced as contaminants in cargo, would likely require a substantial increase in inspection efforts by APHIS personnel."
  1. ^ p. 39, Table 2

References

  1. ^ Agrios GN (1972). Plant Pathology (3rd ed.). Academic Press.
  2. PMID 33173596
    .
  3. ^ Yu. T Dyakov, Chapter 0 - Overview on parasitism, Editors: Yu, T. Dyakov, V.G. Dzhavakhiya, T. Korpela, Studies in Plant Science, Comprehensive and Molecular Phytopathology, Elsevier, 2007, Pages 3-17, ISSN 0928-3420, ISBN 9780444521323, https://doi.org/10.1016/B978-044452132-3/50003-1.
  4. ^ Begerow, D.; Schäfer, A.M.; Kellner, R.; Yurkov, A.; Kemler, M.; Oberwinkler, F.; Bauer, R. (2014). "Ustilaginomycotina.". In McLaughlin, D.J.; Spatafora, J.W. (eds.). The Mycota. Vol. VII Part A. Systematics and Evolution (2 ed.). Berlin.: Springer-Verlag. pp. 295–329.
  5. ISBN 1-900347-69-5
    .
  6. National Invasive Species Information Center
    . 2012-02-24. Retrieved 2020-12-06.
  7. ^ "Fungi", Lillian E Hawker, 1966, p. 167
  8. ^ Daley, Jason (15 October 2018). "This Humongous Fungus Is as Massive as Three Blue Whales". Smithsonian.com. Smithsonian Institution. Retrieved 21 October 2018.
  9. ^ a b Davis N (September 9, 2009). "Genome of Irish potato famine pathogen decoded". Haas et al. Broad Institute of MIT and Harvard. Retrieved 24 July 2012.
  10. ISSN 0100-5405
    .
  11. PMID 25178392
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  12. PMID 19019002
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  13. ^ "Scientists discover how deadly fungal microbes enter host cells". (VBI) at Virginia Tech affiliates. Physorg. July 22, 2010. Retrieved July 31, 2012.
  14. PMID 29024322
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  15. ISBN 978-1-904455-37-0
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  17. PMID 31578554
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  18. ^ "Research team unravels tomato pathogen's tricks of the trade". Virginia Tech. 2011.
  19. S2CID 23419581
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  20. PMID 30795425
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  21. PMID 26450274
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  22. PMID 35187578
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  23. PMID 3253512
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  24. ^ Schutzki, R.E.; Cregg, B. (2007). "Abiotic plant disorders: Symptoms, signs and solutions. A diagnostic guide to problem solving" (PDF). Michigan State University Department of Horticulture. Michigan State University. Archived from the original (PDF) on 24 September 2015. Retrieved 10 April 2015.
  25. S2CID 93883640
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  26. ^ a b International Plant Protection Convention (IPPC) (2021). Strategic framework for the International Plant Protection Convention (IPPC) 2020–2030 : Protecting global plant resources and facilitating safe trade. Rome: UN FAO (Food and Agriculture Organization of the United Nations). pp. viii + 28.
  27. ^ Dufour, Rex (July 2015). Tipsheet: Crop Rotation in Organic Farming Systems (Report). National Center for Appropriate Technology. Retrieved 4 May 2016.
  28. doi:10.1071/pp9910571
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  30. PMID 29787730
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External links
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