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{{short description|Scientific study of plant diseases}}
{{short description|Scientific study of plant diseases}}
{{For-multi|the journal|Plant Pathology (journal){{!}}''Plant Pathology'' (journal)|creatures that damage crops and forestry|Pest (organism)}}
{{For-multi|the journal|Plant Pathology (journal){{!}}''Plant Pathology'' (journal)|organisms that damage crops and forestry|Pest (organism)}}
{{Redirect|Phytopathology|the journal|Phytopathology (journal){{!}}''Phytopathology'' (journal)}}
{{Redirect|Phytopathology|the journal|Phytopathology (journal){{!}}''Phytopathology'' (journal)}}
{{Redirect|Plant disease|the journal|Plant Disease (journal){{!}}''Plant Disease'' (journal)}}


[[File:Black rot lifecycle.tif|thumb|upright=1.5|Life cycle of the black rot pathogen, the [[Gram-negative bacteria|gram negative]] bacterium [[Xanthomonas campestris pv. campestris|''Xanthomonas campestris'' pathovar ''campestris'']]]]
[[File:Black rot lifecycle.tif|thumb|upright=1.75<!--for readability of diagram text-->|Life cycle of the black rot pathogen, the [[Gram-negative bacteria|gram negative]] bacterium [[Xanthomonas campestris pv. campestris|''Xanthomonas campestris'' pathovar ''campestris'']]]]
'''Plant pathology''' or '''phytopathology''' is the scientific study of [[disease]]s in [[plant]]s caused by [[pathogen]]s (infectious organisms) and environmental conditions (physiological factors).<ref>{{cite book |vauthors=Agrios GN |title=Plant Pathology |edition=3rd |publisher=Academic Press |date=1972}}</ref> Organisms that cause infectious disease include [[fungus|fungi]], [[oomycetes]], [[bacterium|bacteria]], [[plant virus|viruses]], [[viroid]]s, [[virus]]-like organisms, [[phytoplasmas]], [[protozoa]], [[nematode]]s and [[parasitic plant]]s.<ref>{{cite journal |vauthors=Nazarov PA, Baleev DN, Ivanova MI, Sokolova LM, Karakozova MV |title=Infectious Plant Diseases: Etiology, Current Status, Problems and Prospects in Plant Protection |journal=Acta Naturae |volume=12 |issue=3 |pages=46–59 |date=2020-10-27 |pmid=33173596 |pmc=7604890 |doi=10.32607/actanaturae.11026 }}</ref> Not included are [[ectoparasites]] like [[insects]], [[mites]], [[vertebrate]], or other [[Plant defense against herbivory|pests that affect plant health]] by eating [[plant tissue]]s and causing injury that may admit plant pathogens. Plant pathology also involves the study of pathogen identification, disease [[etiology]], disease cycles, economic impact, [[plant disease epidemiology]], [[plant disease resistance]], how plant diseases affect humans and animals, [[pathosystem]] genetics, and management of plant diseases.
'''Plant pathology''' or '''phytopathology''' is the scientific study of [[plant disease]]s caused by [[pathogen]]s (infectious organisms) and environmental conditions (physiological factors).<ref>{{cite book |vauthors=Agrios GN |title=Plant Pathology |edition=3rd |publisher=Academic Press |date=1972}}</ref> Plant pathology involves the study of pathogen identification, disease [[etiology]], disease cycles, economic impact, [[plant disease epidemiology]], [[plant disease resistance]], how plant diseases affect humans and animals, [[pathosystem]] genetics, and management of plant diseases.


== Plant pathogens ==
== Plant pathogenicity ==


{{further|Lists of plant diseases}}
{{further|Plant disease}}


In most plant [[pathosystem]]s, [[virulence]] depends on [[hydrolase]]s and enzymes that degrade the [[cell wall]]. The vast majority of these act on [[pectin]]s (for example, [[pectinesterase]], [[pectate lyase]], and [[pectinase]]s). For microbes, the cell wall [[polysaccharide]]s are both a food source and a barrier to be overcome. Many pathogens grow opportunistically when the host breaks down its own cell walls, most often during [[fruit ripening]].<ref name="Cantu-et-al-2008">{{cite journal |vauthors=Cantu D, Vicente AR, Labavitch JM, Bennett AB, Powell AL |title=Strangers in the matrix: plant cell walls and pathogen susceptibility |journal=Trends in Plant Science |volume=13 |issue=11 |pages=610–617 |date=November 2008 |pmid=18824396 |doi=10.1016/j.tplants.2008.09.002 |publisher=[[Cell Press]] |hdl=11336/148749 }} {{small|1=(ARV [[ORCID]]: [http://orcid.org/0000-0003-1289-9554 0000-0003-1289-9554])}}.</ref> Unlike human and animal pathology, plant pathology usually focuses on a single causal organism; however, some plant diseases have been shown to be interactions between multiple pathogens.<ref>{{cite journal |vauthors=Lamichhane JR, Venturi V |year=2015 |title=Synergisms between microbial pathogens in plant disease complexes: a growing trend |journal=Frontiers in Plant Science |volume=6 |issue=385 |doi=10.3389/fpls.2015.00385 |doi-access=free }}</ref>
Plant pathogens, organisms that cause infectious [[plant disease]]s, include [[fungus|fungi]], [[oomycetes]], [[bacterium|bacteria]], [[plant virus|viruses]], [[viroid]]s, [[virus]]-like organisms, [[phytoplasmas]], [[protozoa]], [[nematode]]s and [[parasitic plant]]s.<ref>{{cite journal |vauthors=Nazarov PA, Baleev DN, Ivanova MI, Sokolova LM, Karakozova MV |title=Infectious Plant Diseases: Etiology, Current Status, Problems and Prospects in Plant Protection |journal=Acta Naturae |volume=12 |issue=3 |pages=46–59 |date=2020-10-27 |pmid=33173596 |pmc=7604890 |doi=10.32607/actanaturae.11026 }}</ref>
<!--
Please do not list plant diseases or pathogens here, or describe the diseases,
— that is the work of the [[Plant disease]] article, not this one. Thanks.
-->
In most plant [[pathosystem]]s, [[virulence]] depends on [[hydrolase]]s and enzymes that degrade the [[cell wall]]. The vast majority of these act on [[pectin]]s (for example, [[pectinesterase]], [[pectate lyase]], and [[pectinase]]s). For microbes, the cell wall [[polysaccharide]]s are both a food source and a barrier to be overcome. Many pathogens grow opportunistically when the host breaks down its own cell walls, most often during [[fruit ripening]].<ref name="Cantu-et-al-2008">{{cite journal |vauthors=Cantu D, Vicente AR, Labavitch JM, Bennett AB, Powell AL |title=Strangers in the matrix: plant cell walls and pathogen susceptibility |journal=Trends in Plant Science |volume=13 |issue=11 |pages=610–617 |date=November 2008 |pmid=18824396 |doi=10.1016/j.tplants.2008.09.002 |publisher=[[Cell Press]] |hdl=11336/148749 |hdl-access=free }} {{small|1=(ARV [[ORCID]]: [http://orcid.org/0000-0003-1289-9554 0000-0003-1289-9554])}}.</ref> Unlike human and animal pathology, plant pathology usually focuses on a single causal organism; however, some plant diseases have been shown to be interactions between multiple pathogens.<ref>{{cite journal |vauthors=Lamichhane JR, Venturi V |year=2015 |title=Synergisms between microbial pathogens in plant disease complexes: a growing trend |journal=Frontiers in Plant Science |volume=6 |issue=385 |page=385 |doi=10.3389/fpls.2015.00385 |doi-access=free |pmid=26074945 |pmc=4445244 }}</ref>

=== Fungi ===

[[File:Powdery mildew.JPG|thumb|[[Powdery mildew]], a biotrophic [[Ascomycota|Ascomycete]] fungus]]

Most phytopathogenic fungi are [[Ascomycota|Ascomycetes]] or [[Basidiomycota|Basidiomycetes]]. They reproduce both [[sexual reproduction|sexually]] and [[asexual reproduction|asexually]] via the production of [[spores]] and other structures. Spores may be spread long distances by air or water, or they may be soil borne. Many soil inhabiting fungi are capable of living [[saprotroph]]ically, 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 [[Race (biology)|races]] of fungi often [[evolution|evolve]] that are resistant to various fungicides.
Biotrophic fungal pathogens colonize living plant tissue and obtain nutrients from living host cells. [[Necrotroph]]ic fungal pathogens infect and kill host tissue and extract nutrients from the dead host cells.<ref>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.</ref>

Significant fungal plant pathogens include:

==== Ascomycetes ====

* ''[[Fusarium]]'' spp. (Fusarium wilt disease)
* ''[[Thielaviopsis]]'' spp. (canker rot, black root rot, ''Thielaviopsis'' root rot)
* ''[[Verticillium]]'' spp.
* ''[[Magnaporthe grisea]]'' (rice blast)
* ''[[Sclerotinia sclerotiorum]]'' (cottony rot)

==== Basidiomycetes ====

[[File:Wheat leaf rust on wheat (detail).jpg|thumb|Wheat leaf rust caused by the Basidiomycete ''[[Puccinia tricicina]]'' ]]

* ''[[Ustilago]]'' spp. (smuts)<ref name=Begerow>{{cite book |last1=Begerow |first1=D. |last2=Schäfer |first2=A.M. |last3=Kellner |first3=R. |last4=Yurkov |first4=A. |last5=Kemler |first5=M. |last6=Oberwinkler |first6=F. |last7=Bauer |first7=R. |editor1-last=McLaughlin |editor1-first=D.J. |editor2-last=Spatafora |editor2-first=J.W. |title=The Mycota. Vol. VII Part A. Systematics and Evolution. |date=2014 |publisher=Springer-Verlag |location=Berlin. |pages=295–329 |edition=2 |chapter=Ustilaginomycotina.}}</ref>
* ''[[Rhizoctonia]]'' spp.<ref name="Roberts1999">{{cite book |title=Rhizoctonia-forming fungi |last=Roberts P. |year=1999 |publisher=Royal Botanic Gardens |location=Kew |isbn=1-900347-69-5 |pages=239}}</ref>
* ''[[Soybean rust|Phakospora pachyrhizi]]'' ([[soybean]] rust)<ref name="InvasiveSpecies.gov">{{cite web | title=Soybean Rust | website=[[National Invasive Species Information Center]] | date=2012-02-24 | url=http://www.invasivespeciesinfo.gov/profile/soybean-rust | access-date=2020-12-06}}</ref>
* ''[[Puccinia]]'' spp. (severe rusts of [[cereal]]s and [[grass]]es)(fungus)|rusts]].<ref>"Fungi", Lillian E Hawker, 1966, p. 167</ref>
* ''[[Armillaria]]'' spp. (honey fungus species, virulent pathogens of trees)<ref name="si">{{cite web |last1=Daley |first1=Jason |title=This Humongous Fungus Is as Massive as Three Blue Whales |url=https://www.smithsonianmag.com/smart-news/mushroom-massive-three-blue-whales-180970549/ |website=Smithsonian.com |publisher=Smithsonian Institution |access-date=21 October 2018 |date=15 October 2018}}</ref>

=== Fungus-like organisms ===

==== Oomycetes ====

The [[oomycetes]] are fungus-like organisms among the [[Stramenopiles]].<ref name="watermold"/> They include some of the most destructive plant pathogens, such as the causal agents of [[Phytophthora infestans|potato late blight]]<ref name="watermold" /> [[Pythium|root rot]],<ref name="Sutton-et-al-1990">{{cite journal |last1=Sutton |first1=John Clifford |last2=Sopher |first2=Coralie Rachelle |last3=Owen-Going |first3=Tony Nathaniel |last4=Liu |first4=Weizhong |last5=Grodzinski |first5=Bernard |last6=Hall |first6=John Christopher |last7=Benchimol |first7=Ruth Linda |title=Etiology and epidemiology of ''Pythium'' root rot in hydroponic crops: current knowledge and perspectives |journal=[[Summa Phytopathologica]] |volume=32 |issue=4 |date=1990-01-06 |issn=0100-5405 |doi=10.1590/S0100-54052006000400001 |pages=307–321 |doi-access=free }}</ref> and [[sudden oak death]].<ref>{{cite journal |vauthors=Kamoun S, Furzer O, Jones JD, Judelson HS, Ali GS, Dalio RJ, Roy SG, Schena L, Zambounis A, Panabières F, Cahill D, Ruocco M, Figueiredo A, Chen XR, Hulvey J, Stam R, Lamour K, Gijzen M, Tyler BM, Grünwald NJ, Mukhtar MS, Tomé DF, Tör M, Van Den Ackerveken G, McDowell J, Daayf F, Fry WE, Lindqvist-Kreuze H, Meijer HJ, Petre B, Ristaino J, Yoshida K, Birch PR, Govers F |display-authors=6 |title=The Top 10 oomycete pathogens in molecular plant pathology |journal=Molecular Plant Pathology |volume=16 |issue=4 |pages=413–434 |date=May 2015 |pmid=25178392 |doi=10.1111/mpp.12190 |url=http://ir.library.oregonstate.edu/xmlui/bitstream/1957/58500/1/TylerBrettBotanyPlantPathologyTop10oomycetepathogens.pdf |pmc=6638381 }}</ref><ref>{{cite journal |vauthors=Grünwald NJ, Goss EM, Press CM |title=Phytophthora ramorum: a pathogen with a remarkably wide host range causing sudden oak death on oaks and ramorum blight on woody ornamentals |journal=Molecular Plant Pathology |volume=9 |issue=6 |pages=729–40 |date=November 2008 |pmid=19019002 |doi=10.1111/J.1364-3703.2008.00500.X |pmc=6640315 }}</ref>

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.<ref name="enter host cell">{{cite web |url=http://phys.org/news199007038.html |title=Scientists discover how deadly fungal microbes enter host cells |publisher=Physorg |work=(VBI) at Virginia Tech affiliates |date=July 22, 2010 |access-date=July 31, 2012}}</ref>

==== Phytomyxea ====

Some [[slime mold]]s in [[Phytomyxea]] cause important diseases, including [[clubroot]] in cabbage and its relatives and [[powdery scab]] in potatoes. These are caused by species of ''[[Plasmodiophora]]'' and ''[[Spongospora]]'', respectively.<ref>{{cite journal |last1=Schwelm |first1=Arne |last2=Badstöber |first2=Julia |last3=Bulman |first3=Simon |last4=Desoignies |first4=Nicolas |last5=Etemadi |first5=Mohammad |last6=Falloon |first6=Richard E. |last7=Gachon |first7=Claire M. M. |last8=Legreve |first8=Anne |last9=Lukeš |first9=Julius |last10=Merz |first10=Ueli |last11=Nenarokova |first11=Anna |last12=Strittmatter |first12=Martina |last13=Sullivan |first13=Brooke K. |last14=Neuhauser |first14=Sigrid |display-authors=5 |title=Not in your usual Top 10: protists that infect plants and algae |journal=Molecular Plant Pathology |date=2018 |volume=19 |issue=4 |pages=1029–1044 |doi=10.1111/mpp.12580|pmid=29024322 |pmc=5772912 }}</ref>

{{anchor|Bacteria}}

=== Bacteria ===

[[File:Agrobacteriumgall.jpg|thumb|Crown gall disease caused by [[Agrobacterium]]]]

Most [[bacteria]] associated with plants are [[saprotrophic]] and do no harm to the plant itself. However, a small number, around 100 known species, cause disease, especially in [[subtropical]] and [[tropical]] regions of the world.<ref name=JacksonRW>{{cite book |veditors=Jackson RW |title=Plant Pathogenic Bacteria: Genomics and Molecular Biology |publisher=Caister Academic Press |year=2009 |isbn=978-1-904455-37-0}}</ref>{{pn|date=December 2023}}

Most plant pathogenic bacteria are [[Bacteria#Morphology|bacilli]]. ''[[Erwinia]]'' uses cell wall–degrading enzymes to cause [[Bacterial soft rot|soft rot]]. ''[[Agrobacterium]]'' changes the level of [[auxin]]s to cause tumours with phytohormones.

Significant bacterial plant pathogens include:

* [[Burkholderia]]<ref name="Burkholder 1948">{{cite journal |vauthors=Burkholder WH |title=Bacteria as plant pathogens |journal=Annual Review of Microbiology |volume=2 (1 vol.) |pages=389–412 |date=October 1948 |pmid=18104350 |doi=10.1146/annurev.mi.02.100148.002133 }}</ref>
* [[Pseudomonadota]]
** ''[[Xanthomonas]]'' spp.<ref>{{cite journal | vauthors = An SQ, Potnis N, Dow M, Vorhölter FJ, He YQ, Becker A, Teper D, Li Y, Wang N, Bleris L, Tang JL | display-authors = 6 | title = Mechanistic insights into host adaptation, virulence and epidemiology of the phytopathogen Xanthomonas | journal = FEMS Microbiology Reviews | pages = 1–32 | date = October 2019 | volume = 44 | issue = 1 | pmid = 31578554 | doi = 10.1093/femsre/fuz024 | pmc = 8042644 | doi-access = free }}</ref>
** ''[[Pseudomonas]]'' spp.
* [[Pseudomonas tomato|Pseudomonas syringae pv. tomato]] causes tomato plants to produce less fruit, and it "continues to adapt to the tomato by minimizing its recognition by the tomato immune system."<ref>{{cite web|publisher=Virginia Tech|year=2011|title= Research team unravels tomato pathogen's tricks of the trade|url=http://www.vtnews.vt.edu/articles/2011/11/110311-fralin-tomatopathogen.html}}</ref>

==== Mollicutes ====

[[File:Vitis vinifera phytoplasma.jpg|thumb|[[Vitis vinifera]] with "[[Flavescence dorée|Ca. Phytoplasma vitis]]" infection]]

''[[Phytoplasma]]'' and ''[[Spiroplasma]]'' are obligate [[intracellular parasite]]s, bacteria that lack cell walls and, like the [[mycoplasmas]], which are human pathogens, they belong to the class [[Mollicutes]]. Their cells are extremely small, 1 to 2 micrometres across. They tend to have small [[genomes]] (roughly between 0.5 and 2 Mb). They are normally transmitted by [[leafhopper]]s (cicadellids) and [[Psyllidae|psyllids]], both sap-sucking insect vectors. These inject the bacteria into the plant's [[phloem]], where it reproduces.<ref name="Gasparich 2010">{{cite journal |last=Gasparich |first=Gail E. |title=Spiroplasmas and phytoplasmas: Microbes associated with plant hosts <!--Review--> |journal=[[Biologicals]] |volume=38 |issue=2 |date=2010 |doi=10.1016/j.biologicals.2009.11.007 |pages=193–203|s2cid=23419581 }}</ref>

[[File:Tobacco mosaic virus symptoms tobacco.jpg|thumb|[[Tobacco mosaic virus]] ]]

=== Viruses ===

{{Main|Plant virus}}

Many plant viruses cause only a loss of [[crop yield]]. Therefore, it is not economically viable to try to control them, except when they infect [[perennial plant|perennial]] species, such as fruit trees.{{citation needed|date=February 2023}}

Most plant viruses have small, single-stranded [[RNA]] [[genome]]s. Some also have double stranded [[RNA]] or single or double stranded [[DNA]]. These may encode only three or four [[proteins]]: a [[replicase]], a coat protein, a [[movement protein]] to facilitate cell to cell movement through [[plasmodesmata]], and sometimes a protein that allows transmission by a vector.{{citation needed|date=February 2023}}

Plant viruses are generally transmitted by a [[Vector (epidemiology)|vector]], but mechanical and seed transmission also occur. Vectors are often [[insect]]s such as [[aphid]]s; others are [[fungus|fungi]], [[nematode]]s, 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.<ref>{{cite journal |vauthors=Creamer R, Hubble H, Lewis A |title=Curtovirus Infection of Chile Pepper in New Mexico |journal=Plant Disease |volume=89 |issue=5 |pages=480–486 |date=May 2005 |pmid=30795425 |doi=10.1094/PD-89-0480 |doi-access=free }}</ref>

=== Nematodes ===

{{Main|Nematode}}

[[File:Nematode nodules.jpg|thumb|200px|[[Root-knot nematode]] galls]]

Some [[nematodes]] parasitize plant [[root]]s. They are a problem in [[tropical]] and [[subtropical]] regions. Potato cyst nematodes (''Globodera pallida'' and ''G. rostochiensis'') are widely distributed in Europe and the Americas, causing {{Nowrap|$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,<ref>{{cite journal |vauthors=Huynh BL, Matthews WC, Ehlers JD, Lucas MR, Santos JR, Ndeve A, Close TJ, Roberts PA |display-authors=6 |title=A major QTL corresponding to the Rk locus for resistance to root-knot nematodes in cowpea (Vigna unguiculata L. Walp.) |journal=Theoretical and Applied Genetics |volume=129 |issue=1 |pages=87–95 |date=January 2016 |pmid=26450274 |pmc=4703619 |doi=10.1007/s00122-015-2611-0 }}</ref> 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.<ref>{{cite journal |vauthors=Dos Santos JJ, de Brida AL, Jean-Baptiste MC, Bernardi D, Wilcken SR, Leite LG, Garcia FR |title=Effectiveness of Steinernema rarum PAM 25 (Rhabditida: Steinernematidae) Against Drosophila suzukii (Diptera: Drosophilidae) |journal=Journal of Economic Entomology |volume=115 |issue=4 |pages=967–971 |date=August 2022 |pmid=35187578 |doi=10.1093/jee/toac010 |doi-access=free |veditors=Lee J }}</ref>

=== Protozoa ===

A few plant diseases are caused by [[protozoa]] such as ''[[Phytomonas]]'', a [[Kinetoplastida|kinetoplastid]].<ref>{{cite journal |vauthors=Jankevicius JV, Itow-Jankevicius S, Maeda LA, Campaner M, Conchon I, Carmo JB, Dutra-Menezes MC, Menezes JR, Camargo EP, Roitman I, Traub-Csekö YM |display-authors=5 |title=Ciclo biológico de ''Phytomonas'' |trans-title=Biological cycle of ''Phytomonas'' |language=pt |journal=Memórias do Instituto Oswaldo Cruz |date=1988 |volume=83 |pages=601–10 |doi=10.1590/S0074-02761988000500073 |pmid=3253512 |doi-access=free }}</ref> They are transmitted as durable [[zoospore]]s that may be able to survive in a resting state in the soil for many years. Further, they can transmit plant [[viruses]]. When the motile zoospores come into contact with a [[root hair]] they produce a [[plasmodium]] which invades the [[root]]s.{{citation needed|date=February 2023}}

=== Parasitic plants ===

[[Parasitic plant]]s such as [[Cuscuta|dodder]] can act as a conduit for the transmission of viruses or virus-like agents from a host plant to a plant that is not typically a host, or for an agent that is not graft-transmissible.{{citation needed|date=February 2023}}

== Pathogenicity factors ==


To colonize a plant, pathogens have specific [[pathogenicity factor]]s, of five main types: uses of cell wall–degrading enzymes, [[toxins]], effector proteins, [[phytohormone]]s, and [[exopolysaccharide]]s.
To colonize a plant, pathogens have specific [[pathogenicity factor]]s, of five main types: uses of cell wall–degrading enzymes, [[toxins]], effector proteins, [[phytohormone]]s, and [[exopolysaccharide]]s.
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* '''Cell wall-degrading enzymes''': These are used to break down the plant [[cell wall]] in order to release the nutrients inside and include esterases, glycosyl hydrolases, lyases and oxidoreductases.<ref>{{cite journal |vauthors=Giovannoni M, Gramegna G, Benedetti M, Mattei B |title=Industrial Use of Cell Wall Degrading Enzymes: The Fine Line Between Production Strategy and Economic Feasibility |journal=Frontiers in Bioengineering and Biotechnology |volume=8 |pages=356 |date=2020 |pmid=32411686 |pmc=7200985 |doi=10.3389/fbioe.2020.00356 |doi-access=free }}</ref>
* '''Cell wall-degrading enzymes''': These are used to break down the plant [[cell wall]] in order to release the nutrients inside and include esterases, glycosyl hydrolases, lyases and oxidoreductases.<ref>{{cite journal |vauthors=Giovannoni M, Gramegna G, Benedetti M, Mattei B |title=Industrial Use of Cell Wall Degrading Enzymes: The Fine Line Between Production Strategy and Economic Feasibility |journal=Frontiers in Bioengineering and Biotechnology |volume=8 |pages=356 |date=2020 |pmid=32411686 |pmc=7200985 |doi=10.3389/fbioe.2020.00356 |doi-access=free }}</ref>
* '''[[Toxins]]''': These can be non-host-specific, which damage all plants, or host-specific, which cause damage only on a host plant.
* '''[[Toxins]]''': These can be non-host-specific, which damage all plants, or host-specific, which cause damage only on a host plant.
* '''Effector proteins''': These can be secreted into the extracellular environment or directly into the host cell, often via the [[Type three secretion system]]. Some effectors are known to suppress host defense processes. This can include: reducing the plants internal signaling mechanisms or reduction of phytochemicals production.<ref name="effector">{{cite web |url=http://newsroom.ucr.edu/2587 |title=How do plants fight disease? Breakthrough research by UC Riverside plant pathologist offers a clue |publisher=UC Riverside |date=March 28, 2011 |author=Ma, Winbo}}</ref> Bacteria, fungus and oomycetes are known for this function.<ref name="watermold">{{cite web |url=http://www.broadinstitute.org/news/1328 |title=Genome of Irish potato famine pathogen decoded |publisher=Broad Institute of MIT and Harvard |work=Haas et al. |date=September 9, 2009 |access-date=24 July 2012 |vauthors=Davis N }}</ref><ref name="Oomycetes">{{cite web |url=http://www.dana-farber.org/Newsroom/News-Releases/First-large-scale-map-of-a-plant-s-protein-network-addresses-evolution,-disease-process.aspx |title=1st large-scale map of a plant's protein network addresses evolution, disease process |date=July 29, 2011 |publisher=Dana-Farber Cancer Institute |access-date=24 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120512073154/http://www.dana-farber.org/Newsroom/News-Releases/First-large-scale-map-of-a-plant-s-protein-network-addresses-evolution,-disease-process.aspx |archive-date=12 May 2012 }}</ref>
* '''Effector proteins''': These can be secreted by pathogens such as bacteria, fungi, and oomycetes<ref name="watermold">{{cite web |url=http://www.broadinstitute.org/news/1328 |title=Genome of Irish potato famine pathogen decoded |publisher=Broad Institute of MIT and Harvard |work=Haas et al. |date=September 9, 2009 |access-date=24 July 2012 |vauthors=Davis N }}</ref><ref name="Oomycetes">{{cite web |url=http://www.dana-farber.org/Newsroom/News-Releases/First-large-scale-map-of-a-plant-s-protein-network-addresses-evolution,-disease-process.aspx |title=1st large-scale map of a plant's protein network addresses evolution, disease process |date=July 29, 2011 |publisher=Dana-Farber Cancer Institute |access-date=24 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120512073154/http://www.dana-farber.org/Newsroom/News-Releases/First-large-scale-map-of-a-plant-s-protein-network-addresses-evolution,-disease-process.aspx |archive-date=12 May 2012 }}</ref> into the extracellular environment or directly into the host cell, often via the [[Type three secretion system]]. Some effectors are known to suppress host defense processes. This can include reducing the plant's internal signaling mechanisms or reduction of phytochemicals production.<ref name="effector">{{cite web |url=http://newsroom.ucr.edu/2587 |title=How do plants fight disease? Breakthrough research by UC Riverside plant pathologist offers a clue |publisher=UC Riverside |date=March 28, 2011 |author=Ma, Winbo}}</ref>
* '''[[Phytohormone]]s''' are chemicals used by plants for signaling; pathogens can produce these to modify plant growth to their own advantage.
* '''[[Phytohormone]]s''' are chemicals used by plants for signaling; pathogens can produce these to modify plant growth to their own advantage.
* '''[[Exopolysaccharide]]s''' are mostly small chains of sugars that help pathogens to adhere to a plant's surface, enabling them to begin the process of infection.
* '''[[Exopolysaccharide]]s''' are mostly small chains of sugars that help pathogens to adhere to a plant's surface, enabling them to begin the process of infection.
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Some abiotic disorders can be confused with pathogen-induced disorders. Abiotic causes include natural processes such as [[drought]], [[frost]], [[snow]] and [[hail]]; [[flood]]ing and poor drainage; [[Micronutrient deficiency|nutrient deficiency]]; deposition of mineral salts such as [[sodium chloride]] and [[gypsum]]; [[wind]]burn and breakage by storms; and [[wildfire]]s. <ref name=Schutzki2007>{{cite web |last1=Schutzki |first1=R.E. |last2=Cregg |first2=B. |title=Abiotic plant disorders: Symptoms, signs and solutions. A diagnostic guide to problem solving |url=http://www.hrt.msu.edu/assets/PagePDFs/bert-cregg/schutski-and-cregg-abiotic.pdf |website=Michigan State University Department of Horticulture |publisher=Michigan State University |accessdate=10 April 2015 |date=2007 |url-status=dead |archiveurl=https://web.archive.org/web/20150924031539/http://www.hrt.msu.edu/assets/PagePDFs/bert-cregg/schutski-and-cregg-abiotic.pdf |archivedate=24 September 2015 }}</ref>
Some abiotic disorders can be confused with pathogen-induced disorders. Abiotic causes include natural processes such as [[drought]], [[frost]], [[snow]] and [[hail]]; [[flood]]ing and poor drainage; [[Micronutrient deficiency|nutrient deficiency]]; deposition of mineral salts such as [[sodium chloride]] and [[gypsum]]; [[wind]]burn and breakage by storms; and [[wildfire]]s. <ref name=Schutzki2007>{{cite web |last1=Schutzki |first1=R.E. |last2=Cregg |first2=B. |title=Abiotic plant disorders: Symptoms, signs and solutions. A diagnostic guide to problem solving |url=http://www.hrt.msu.edu/assets/PagePDFs/bert-cregg/schutski-and-cregg-abiotic.pdf |website=Michigan State University Department of Horticulture |publisher=Michigan State University |accessdate=10 April 2015 |date=2007 |url-status=dead |archiveurl=https://web.archive.org/web/20150924031539/http://www.hrt.msu.edu/assets/PagePDFs/bert-cregg/schutski-and-cregg-abiotic.pdf |archivedate=24 September 2015 }}</ref>

[[File:Tobacco mosaic virus symptoms orchid.jpg|thumb|x130px|Orchid leaves with viral infections|right]]


== Epidemiology ==
== Epidemiology ==


{{Main|Plant disease epidemiology}}
{{main|Plant disease epidemiology}}

[[File:Plant Disease Triangle.svg|thumb|Plant disease triangle]]


Epidemiology is the study of factors affecting the outbreak and spread of infectious diseases.<ref>{{Cite web |url=https://www.apsnet.org/ |title=American Phytopathological Society |website=American Phytopathological Society |access-date=2019-03-26}}</ref>
Epidemiology is the study of factors affecting the outbreak and spread of infectious diseases.<ref>{{Cite web |url=https://www.apsnet.org/ |title=American Phytopathological Society |website=American Phytopathological Society |access-date=2019-03-26}}</ref>


A disease triangle describes the basic factors required for plant diseases. These are the host plant, the pathogen, and the environment. Any one of these can be modified to control a disease.<ref>{{cite web |title=Disease Triangle |date=25 April 2014 |url=https://horticulture.oregonstate.edu/nursery/nursery/disease-triangle |publisher=Oregon State University |access-date=31 December 2023}}</ref>
[[File:Plant Disease Triangle.svg|thumb|Plant disease triangle]]

A disease pyramid best captures the elements involved with plant diseases. This pyramid uses the disease triangle as a foundation, consisting of elements such as: host, pathogen and environment. In addition to these three elements, humans and time add the remaining elements to create a disease tetrahedron.


== Disease resistance ==
== Disease resistance ==


{{Main|Plant disease resistance}}
{{main|Plant disease resistance}}


Plant disease resistance is the ability of a plant to prevent and terminate infections from plant pathogens. Structures that help plants prevent pathogens from entering are the cuticular layer, cell walls and stomata guard cells. Once pathogens have overcome these barriers, plant receptors initiate signaling pathways to create molecules to compete against the foreign molecules. These pathways are influenced and triggered by genes within the host plant and can manipulated by genetic breeding to create resistant varieties.<ref>{{cite journal |vauthors=Andersen EJ, Ali S, Byamukama E, Yen Y, Nepal MP |title=Disease Resistance Mechanisms in Plants |journal=Genes |volume=9 |issue=7 |pages=339 |date=July 2018 |pmid=29973557 |pmc=6071103 |doi=10.3390/genes9070339 |doi-access=free }}</ref>
Plant disease resistance is the ability of a plant to prevent and terminate infections from plant pathogens. Structures that help plants prevent pathogens from entering are the cuticular layer, cell walls and stomata guard cells. Once pathogens have overcome these barriers, plant receptors initiate signaling pathways to create molecules to compete against the foreign molecules. These pathways are influenced and triggered by genes within the host plant and can manipulated by genetic breeding to create resistant varieties.<ref>{{cite journal |vauthors=Andersen EJ, Ali S, Byamukama E, Yen Y, Nepal MP |title=Disease Resistance Mechanisms in Plants |journal=Genes |volume=9 |issue=7 |pages=339 |date=July 2018 |pmid=29973557 |pmc=6071103 |doi=10.3390/genes9070339 |doi-access=free }}</ref>
Line 142: Line 49:
== Management == <!-- [[Phytosanitation]] redirects here -->
== Management == <!-- [[Phytosanitation]] redirects here -->


{{Further|Pest control|Antagonism (phytopathology)}}
{{Further|Antagonism (phytopathology)}}

===Detection===


==Detection==
Ancient methods of leaf examination and breaking open plant material by hand are now augmented by newer technologies. These include [[molecular pathology]] assays such as [[polymerase chain reaction]] (PCR), [[RT-PCR]] and [[loop-mediated isothermal amplification]] (LAMP).<ref name="Mumford-et-al-2006">{{cite journal |vauthors=Mumford R, Boonham N, Tomlinson J, Barker I |title=Advances in molecular phytodiagnostics - new solutions for old problems |journal=European Journal of Plant Pathology |volume=116 |issue=1 |pages=1–19 |date=2006-07-13 |pmid=32214677 |pmc=7087944 |doi=10.1007/s10658-006-9037-0 |publisher=European Foundation for Plant Pathology ([[Springer Science+Business Media|Springer]]) |bibcode=2006EJPP..116....1M }}</ref> Although PCR can detect multiple molecular targets in a single solution there are limits.<ref name="Mumford-et-al-2006" /> Bertolini et al 2001, Ito et al 2002 and Ragozzino et al 2004 developed PCR methods for multiplexing six or seven plant pathogen molecular products and Persson et al 2005 for multiplexing four with RT-PCR.<ref name="Mumford-et-al-2006" /> More extensive [[molecular diagnosis]] requires [[PCR array]]s.<ref name="Mumford-et-al-2006" /> The primary detection method used worldwide is [[enzyme linked immunosorbent assay]].<ref>[https://www.frontiersin.org/articles/10.3389/fpls.2023.1120968/full Current and emerging trends in techniques for plant pathogen detection] ''Frontiers in Plant Science''</ref>
Ancient methods of leaf examination and breaking open plant material by hand are now augmented by newer technologies. These include [[molecular pathology]] assays such as [[polymerase chain reaction]] (PCR), [[RT-PCR]] and [[loop-mediated isothermal amplification]] (LAMP).<ref name="Mumford-et-al-2006">{{cite journal |vauthors=Mumford R, Boonham N, Tomlinson J, Barker I |title=Advances in molecular phytodiagnostics - new solutions for old problems |journal=European Journal of Plant Pathology |volume=116 |issue=1 |pages=1–19 |date=2006-07-13 |pmid=32214677 |pmc=7087944 |doi=10.1007/s10658-006-9037-0 |publisher=European Foundation for Plant Pathology ([[Springer Science+Business Media|Springer]]) |bibcode=2006EJPP..116....1M }}</ref> Although PCR can detect multiple molecular targets in a single solution there are limits.<ref name="Mumford-et-al-2006" /> Bertolini et al 2001, Ito et al 2002 and Ragozzino et al 2004 developed PCR methods for multiplexing six or seven plant pathogen molecular products and Persson et al 2005 for multiplexing four with RT-PCR.<ref name="Mumford-et-al-2006" /> More extensive [[molecular diagnosis]] requires [[PCR array]]s.<ref name="Mumford-et-al-2006" /> The primary detection method used worldwide is [[enzyme linked immunosorbent assay]].<ref>[https://www.frontiersin.org/articles/10.3389/fpls.2023.1120968/full Current and emerging trends in techniques for plant pathogen detection] ''Frontiers in Plant Science''</ref>

{{ Anchor|Port inspection|Port quarantine|Border inspection|Border quarantine}}

=== Port and border inspection and quarantine ===

Another option is to avoid the introduction of harmful nonnative organisms into a country by controlling human traffic (e.g., the [[Australian Quarantine and Inspection Service]]). Global trade provides unprecedented opportunities for the introduction of plant pests.<ref group="McC" name="unprecedented">p.{{spaces}}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."</ref> In the [[United States]], even to get a better estimate of the number of such introductions would require a substantial increase in inspections.<ref group="McC" name="more-inspections">p.{{spaces}}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."</ref> 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.<ref group="BH" name="taxonomy-difficulties">p.{{spaces}}39, '''Table 2'''</ref>

[[X-ray]] and [[Electron-beam processing|electron-beam]]/E-beam [[food irradiation|irradiation of food]] has been trialed as a quarantine treatment for [[fruit]] [[commodity|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.<ref name="Moy-Wong-2002" />

The [[International Plant Protection Convention]] (IPPC) anticipates that [[molecular diagnostics]] for inspections will continue to improve.<ref name="Strategic-Framework-2020-2030" /> Between 2020 and 2030, IPPC expects continued technological improvement to lower costs and improve performance, albeit not for [[less developed countries]] unless funding changes.<ref name="Strategic-Framework-2020-2030">{{Cite book |language =English |year =2021 |location =[[Rome]] |pages =viii + 28 |publisher =UN FAO ([[Food and Agriculture Organization]] of the United Nations) |title =Strategic framework for the International Plant Protection Convention (IPPC) 2020–2030 : Protecting global plant resources and facilitating safe trade |author=[[International Plant Protection Convention]] (IPPC) }}</ref>

=== Plant resistance ===

Sophisticated agricultural developments now allow growers to choose from among systematically cross-bred species to ensure the greatest hardiness in their crops, as suited for a particular region's pathological profile. Breeding practices have been perfected over centuries, but with the advent of genetic manipulation even finer control of a crop's immunity traits is possible. The engineering of food plants may be less rewarding, however, as higher output is frequently offset by popular suspicion and negative opinion about this "tampering" with nature.

=== Chemical ===

{{See also|Pesticide application}}

Many natural and synthetic compounds can be employed to combat the above threats. 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 ===
=== Biological ===


[[Crop rotation]] is a traditional and sometimes effective means of preventing a parasitic population from becoming well-established. For example, protection against infection by ''[[Agrobacterium tumefaciens]]'', which causes gall diseases in many plants, by dipping cuttings in suspensions of ''[[Agrobacterium radiobacter]]'' before inserting them in the ground to take root.<ref>{{Cite journal|vauthors = Ryder MH, Jones DA |date=1991-10-01|title=Biological Control of Crown Gall Using Using Agrobacterium Strains K84 and K1026|journal=[[Functional Plant Biology]]|volume=18|issue=5|pages=571–579|doi=10.1071/pp9910571}}</ref>
[[Crop rotation]] is a traditional and sometimes effective means of preventing a parasitic population from becoming well-established. For example, protection against infection by ''[[Agrobacterium tumefaciens]]'', which causes gall diseases in many plants, by dipping cuttings in suspensions of ''[[Agrobacterium radiobacter]]'' before inserting them in the ground to take root.<ref>{{Cite journal|vauthors = Ryder MH, Jones DA |date=1991-10-01|title=Biological Control of Crown Gall Using Using Agrobacterium Strains K84 and K1026|journal=[[Functional Plant Biology]]|volume=18|issue=5|pages=571–579|doi=10.1071/pp9910571}}</ref>

== 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]].<ref>{{cite journal |vauthors=Martinelli F, Scalenghe R, Davino S, Panno S, Scuderi G, Ruisi P, Villa P, Stroppiana D, Boschetti M, Goulart LR, Davis CE |display-authors=5 |title=Advanced methods of plant disease detection. A review. |journal=Agronomy for Sustainable Development |date=January 2015 |volume=35 |issue=1 |pages=1–25 |doi= 10.1007/s13593-014-0246-1 |s2cid=18000844 |url=https://hal.archives-ouvertes.fr/hal-01284270/file/13593_2014_Article_246.pdf }}</ref>

{{As of|2018}} the most costly diseases of the most produced crops worldwide are:<ref name="Velasquez-et-al-2018">{{cite journal |vauthors=Velásquez AC, Castroverde CD, He SY |title=Plant-Pathogen Warfare under Changing Climate Conditions |journal=Current Biology |volume=28 |issue=10 |pages=R619–R634 |date=May 2018 |pmid=29787730 |pmc=5967643 |doi=10.1016/j.cub.2018.03.054 |publisher=[[Cell Press]] }}</ref>

{|class="wikitable"
! Crop !! Disease Latin name !! Disease common name
|-
|rowspan=3 |[[Banana]] and [[cooking banana|plaintain]] || [[banana bunchy top virus]] (BBTV) || banana bunchy top
|-
|''[[Mycosphaerella fijiensis]]'' || [[black sigatoka]]
|-
|[[Fusarium oxysporum f. sp. cubense|''Fusarium oxysporum'' f.sp. ''cubense'']] || [[Panama disease]]
|-
|rowspan=3 |[[Barley]] || ''[[Fusarium graminearum]]'' || [[Fusarium head blight]]
|-
|[[Blumeria graminis f. sp. hordei|''Blumeria graminis'' f. sp. ''hordei'']] || powdery mildew
|-
|[[Puccinia graminis f. sp. hordei|''Puccinia graminis'' f. sp. ''hordei'']]|| [[barley stem rust]]
|-
|rowspan=3 |[[Cassava]] || [[African cassava mosaic virus|African cassava mosaic virus (ACMVD)]] || African cassava mosaic disease
|-
|[[Xanthomonas axonopodis pv. manihotis|''Xanthomonas axonopodis'' pv. ''manihotis'']]|| bacterial blight
|-
|[[cassava brown streak virus|cassava brown streak virus (CBSV)]] || cassava brown streak disease
|-
|rowspan=3 |[[Cotton]] || [[Xanthomonas citri pv. malvacearum|''Xanthomonas citri'' pv. ''malvacearum'']]|| bacterial blight
|-
| [[Fusarium oxysporum f. sp. vasinfectum|''Fusarium oxysporum'' f. sp. ''vasinfectum'']]|| [[Fusarium wilt]]
|-
|''[[Verticillium dahliae]]'' || [[Verticillium wilt]]
|-
|rowspan=3 |[[Maize|Maize/corn]] || ''[[Aspergillus flavus]]'' || [[Aspergillus ear rot]]
|-
|''[[Fusarium graminearum]]'' || [[Giberella stalk and ear rot]]
|-
|''[[Cercospora zeae-maydis]]'' || [[grey leaf spot]]
|-
|rowspan=2 |[[Palm fruit]] || ''[[Ganoderma orbiforme|Ganoderma orbiforme/Ganoderma boninense]]'' || [[Basal stem rot]]
|-
|''[[Phytophthora palmivora]]'' || [[bud rot]]
|-
|rowspan=3 |[[Peanut]] || [[groundnut rosette virus|groundnut rosette virus (GNV)]] || rowspan=3 |[[Groundnut rosette disease]]
|-
|GNV satellite RNA
|-
|[[groundnut rosette assistor virus|groundnut rosette assistor virus (GRAV)]]
|-
|rowspan=2 |[[Potato]] || ''[[Ralstonia solanacearum]]'' || [[Potato brown rot]]
|-
|''[[Phytophthora infestans]]'' || [[late blight]]
|-
|rowspan=2 |[[Rapeseed]] and [[mustard plant|mustard]] || ''[[Leptosphaeria maculans]]'' || [[Phoma stem canker]]
|-
|''[[Sclerotinia sclerotiorum]]'' || [[Sclerotinia stem rot]]
|-
|rowspan=3 |[[Rice]] || ''[[Magnaporthe oryzae]]'' || [[rice blast]]
|-
|[[Xanthomonas oryzae pv. oryzae|''Xanthomonas oryzae'' pv. ''oryzae'']] || [[rice bacterial blight]]
|-
|''[[Rhizoctonia solani]]'' || [[sheath blight]]
|-
|rowspan=2 |[[Sorghum]] and [[millet]] || ''[[Colletotrichum sublineolum]]'' || [[Anthracnose]]
|-
|''[[Exserohilum turcicum]]'' || [[Turcicum leaf blight]]
|-
|rowspan=2 |[[Soybean]] || ''[[Heterodera glycines]]'' || [[soybean cyst nematode disease]]
|-
|''[[Phakopsora pachyrhizi]]'' || [[Asian soybean rust]]
|-
|rowspan=2 |[[Sugar beet]] || ''[[Cercospora beticola]]'' || [[Cercospora leaf spot]]
|-
| [[beet necrotic yellow vein virus|beet necrotic yellow vein virus (BNYVV)]] || [[rhizomania]]
|-
|rowspan=2 |[[Sugarcane]] || [[Leifsonia xyli subsp. xyli|''Leifsonia xyli'' subsp. ''xyli'']]|| [[Ratoon stunting]]
|-
|''[[Colletotrichum falcatum]]'' || red rot
|-
|rowspan=2 |[[Sweet potato]] || [[sweet potato feathery mottle virus|sweet potato feathery mottle virus (SPFMV)]] || rowspan=2 |[[sweet potato virus disease|sweet potato virus disease (SPVD)]]
|-
|[[sweet potato chlorotic stunt virus|sweet potato chlorotic stunt virus (SPCSV)]]
|-
|rowspan=2 |[[Tomato]] || ''Phytophthora infestans'' || late blight
|-
|[[tomato yellow leaf curl virus|tomato yellow leaf curl virus (TYLCV)]] || tomato yellow leaf curl
|-
|rowspan=3 |[[Wheat]] || ''[[Fusarium graminearum]]'' || [[Fusarium head blight]]
|-
|''[[Puccinia graminis]]'' || [[wheat stem rust]]
|-
|''[[Puccinia striiformis]]'' || [[wheat yellow rust]]
|-
|rowspan=2 |[[Yam (vegetable)|Yam]] || ''[[Colletotrichum gloeosporioides]]'' || anthracnose
|-
|[[yam mosaic virus|yam mosaic virus (YMV)]]|| [[yam mosaic disease]]
|}


== History ==
== History ==
Line 280: Line 70:
* [[American Phytopathological Society]]
* [[American Phytopathological Society]]
* [[Australasian Plant Pathology Society]]
* [[Australasian Plant Pathology Society]]
* [[Biological pest control#Biological control with micro-organisms|Biological control with micro-organisms]]
* [[British Society for Plant Pathology]]
* [[British Society for Plant Pathology]]
* [[Burl]]
* [[Common names of plant diseases]]
* [[Forest pathology]]
* [[Forest pathology]]
* [[Gene-for-gene relationship]]
* [[Gene-for-gene relationship]]
* [[Global Plant Clinic]]
* [[Global Plant Clinic]]
* [[Glossary of phytopathology]]
* [[Glossary of phytopathology]]
* [[Herbivory]]
* [[Horsfall-Barratt scale]]
* [[Horsfall-Barratt scale]]
* [[List of phytopathology journals]]
* [[List of phytopathology journals]]
Line 302: Line 88:


== References ==
== References ==
{{reflist|30em|refs=
{{reflist|30em}}

<ref name="Moy-Wong-2002">{{cite journal |vauthors=Moy JH, Wong L |title=The efficacy and progress in using radiation as a quarantine treatment of tropical fruits — A case study in Hawaii |journal= Radiation Physics and Chemistry |publisher=[[Elsevier]] BV |volume=63 |issue=3–6 |year=2002 |issn=0969-806X |doi=10.1016/s0969-806x(01)00557-6 |pages=397–401 |bibcode=2002RaPC...63..397M |s2cid=93883640}}</ref>

}}


== External links ==
== External links ==
Line 324: Line 106:
* [https://web.archive.org/web/20090415135148/http://www.iasma.it/sperimentazione_context2.jsp?ID_LINK=2535&area=6 Opportunity in Plant Pathology]
* [https://web.archive.org/web/20090415135148/http://www.iasma.it/sperimentazione_context2.jsp?ID_LINK=2535&area=6 Opportunity in Plant Pathology]
* [https://www.facebook.com/pages/Asian-Association-of-Societies-for-Plant-Pathology/239732732854143 Facebook page for Asian Association of Societies for Plant Pathology]
* [https://www.facebook.com/pages/Asian-Association-of-Societies-for-Plant-Pathology/239732732854143 Facebook page for Asian Association of Societies for Plant Pathology]
* [https://www.globalgarden.co/knowledge/the-pest-and-pathogens-glossary/ The Pest and Pathogens Glossary]
{{refend}}
{{refend}}


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[[Category:Phytopathology|Phytopathology]]
[[Category:Phytopathology|Phytopathology]]
[[Category:Agronomy]]
[[Category:Agronomy]]
[[Category:Pathology]]
[[Category:Plant diseases]]

Latest revision as of 09:33, 11 April 2024

For the journal, see Plant Pathology (journal). For organisms that damage crops and forestry, see Pest (organism).
"Phytopathology" redirects here. For the journal, see Phytopathology (journal).
Life cycle of the black rot pathogen, the gram negative bacterium Xanthomonas campestris pathovar campestris

Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors).[1] Plant pathology involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.

Plant pathogenicity[edit]

Further information: Plant disease

Plant pathogens, organisms that cause infectious plant diseases, include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants.[2] In most plant pathosystems, virulence depends on hydrolases and enzymes that degrade the cell wall. The vast majority of these act on pectins (for example, pectinesterase, pectate lyase, and pectinases). For microbes, the cell wall polysaccharides are both a food source and a barrier to be overcome. Many pathogens grow opportunistically when the host breaks down its own cell walls, most often during fruit ripening.[3] Unlike human and animal pathology, plant pathology usually focuses on a single causal organism; however, some plant diseases have been shown to be interactions between multiple pathogens.[4]

To colonize a plant, pathogens have specific pathogenicity factors, of five main types: uses of cell wall–degrading enzymes, toxins, effector proteins, phytohormones, and exopolysaccharides.

  • Cell wall-degrading enzymes: These are used to break down the plant cell wall in order to release the nutrients inside and include esterases, glycosyl hydrolases, lyases and oxidoreductases.[5]
  • Toxins: These can be non-host-specific, which damage all plants, or host-specific, which cause damage only on a host plant.
  • Effector proteins: These can be secreted by pathogens such as bacteria, fungi, and oomycetes[6][7] into the extracellular environment or directly into the host cell, often via the Type three secretion system. Some effectors are known to suppress host defense processes. This can include reducing the plant's internal signaling mechanisms or reduction of phytochemicals production.[8]
  • Phytohormones are chemicals used by plants for signaling; pathogens can produce these to modify plant growth to their own advantage.
  • Exopolysaccharides are mostly small chains of sugars that help pathogens to adhere to a plant's surface, enabling them to begin the process of infection.

Physiological plant disorders[edit]

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. [9]

Epidemiology[edit]

Main article: Plant disease epidemiology
Plant disease triangle

Epidemiology is the study of factors affecting the outbreak and spread of infectious diseases.[10]

A disease triangle describes the basic factors required for plant diseases. These are the host plant, the pathogen, and the environment. Any one of these can be modified to control a disease.[11]

Disease resistance[edit]

Main article: Plant disease resistance

Plant disease resistance is the ability of a plant to prevent and terminate infections from plant pathogens. Structures that help plants prevent pathogens from entering are the cuticular layer, cell walls and stomata guard cells. Once pathogens have overcome these barriers, plant receptors initiate signaling pathways to create molecules to compete against the foreign molecules. These pathways are influenced and triggered by genes within the host plant and can manipulated by genetic breeding to create resistant varieties.[12]

Management[edit]

Further information: Antagonism (phytopathology)

Detection[edit]

Ancient methods of leaf examination and breaking open plant material by hand are now augmented by newer technologies. These include molecular pathology assays such as polymerase chain reaction (PCR), RT-PCR and loop-mediated isothermal amplification (LAMP).[13] Although PCR can detect multiple molecular targets in a single solution there are limits.[13] Bertolini et al 2001, Ito et al 2002 and Ragozzino et al 2004 developed PCR methods for multiplexing six or seven plant pathogen molecular products and Persson et al 2005 for multiplexing four with RT-PCR.[13] More extensive molecular diagnosis requires PCR arrays.[13] The primary detection method used worldwide is enzyme linked immunosorbent assay.[14]

Biological[edit]

Crop rotation is a traditional and sometimes effective means of preventing a parasitic population from becoming well-established. For example, protection against infection by Agrobacterium tumefaciens, which causes gall diseases in many plants, by dipping cuttings in suspensions of Agrobacterium radiobacter before inserting them in the ground to take root.[15]

History[edit]

Further information: Timeline of plant pathology

Plant pathology has developed from antiquity, starting with Theophrastus in the ancient era, but scientific study began in the Early Modern period with the invention of the microscope, and developed in the 19th century.[16]

See also[edit]

Notes[edit]

References[edit]

  1. ^ Agrios GN (1972). Plant Pathology (3rd ed.). Academic Press.
  2. ^ Nazarov PA, Baleev DN, Ivanova MI, Sokolova LM, Karakozova MV (2020-10-27). "Infectious Plant Diseases: Etiology, Current Status, Problems and Prospects in Plant Protection". Acta Naturae. 12 (3): 46–59. doi:10.32607/actanaturae.11026. PMC 7604890. PMID 33173596.
  3. ^ Cantu D, Vicente AR, Labavitch JM, Bennett AB, Powell AL (November 2008). "Strangers in the matrix: plant cell walls and pathogen susceptibility". Trends in Plant Science. 13 (11). Cell Press: 610–617. doi:10.1016/j.tplants.2008.09.002. hdl:11336/148749. PMID 18824396. (ARV ORCID: 0000-0003-1289-9554).
  4. ^ Lamichhane JR, Venturi V (2015). "Synergisms between microbial pathogens in plant disease complexes: a growing trend". Frontiers in Plant Science. 6 (385): 385. doi:10.3389/fpls.2015.00385. PMC 4445244. PMID 26074945.
  5. ^ Giovannoni M, Gramegna G, Benedetti M, Mattei B (2020). "Industrial Use of Cell Wall Degrading Enzymes: The Fine Line Between Production Strategy and Economic Feasibility". Frontiers in Bioengineering and Biotechnology. 8: 356. doi:10.3389/fbioe.2020.00356. PMC 7200985. PMID 32411686.
  6. ^ 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.
  7. ^ "1st large-scale map of a plant's protein network addresses evolution, disease process". Dana-Farber Cancer Institute. July 29, 2011. Archived from the original on 12 May 2012. Retrieved 24 July 2012.
  8. ^ Ma, Winbo (March 28, 2011). "How do plants fight disease? Breakthrough research by UC Riverside plant pathologist offers a clue". UC Riverside.
  9. ^ 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.
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  13. ^ a b c d Mumford R, Boonham N, Tomlinson J, Barker I (2006-07-13). "Advances in molecular phytodiagnostics - new solutions for old problems". European Journal of Plant Pathology. 116 (1). European Foundation for Plant Pathology (Springer): 1–19. Bibcode:2006EJPP..116....1M. doi:10.1007/s10658-006-9037-0. PMC 7087944. PMID 32214677.
  14. ^ Current and emerging trends in techniques for plant pathogen detection Frontiers in Plant Science
  15. ^ Ryder MH, Jones DA (1991-10-01). "Biological Control of Crown Gall Using Using Agrobacterium Strains K84 and K1026". Functional Plant Biology. 18 (5): 571–579. doi:10.1071/pp9910571.
  16. ^ Aisnworth GC (1981). Introduction to the History of Plant Pathology. Cambridge University Press. ISBN 978-0-521-23032-2.

External links[edit]

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