Editing Rust (fungus)

{{Short description|Order of fungi}}
{{Automatic taxobox 
| name = Rusts
| image = Bruine roest op tarwe (Puccinia recondita f.sp. tritici on Triticum aestivum).jpg
| image_caption = Example of wheat leaf from a disease differential of [[Puccinia recondita f.sp. tritici|''Puccinia recondita'' f.sp. ''tritici'']]
| taxon = Pucciniales
| authority =
| subdivision_ranks = Families
| subdivision =
*[[Araucariomycetaceae]]<ref name = A&M2021/>
*([[Chaconiaceae]])
*[[Coleosporiaceae]]
*([[Cronartiaceae]])
*[[Crossopsoraceae]]<ref name = A&M2021/>
*[[Gymnosporangiaceae]]
*[[Melampsoraceae]]
*[[Milesinaceae]]<ref name = A&M2021/>
*[[Ochropsoraceae]]<ref name = A&M2021/>
*[[Phakopsoraceae]]
*[[Phragmidiaceae]]
*[[Pileolariaceae]]
*[[Pucciniaceae]]
*[[Pucciniosiraceae]]
*[[Pucciniastraceae]]
*[[Raveneliaceae]]
*[[Rogerpetersoniaceae]]<ref name = A&M2021/>
*[[Skierkaceae]]<ref>{{cite web |title=Species Fungorum - Search Page |url=http://www.speciesfungorum.org/Names/Names.asp?strGenus=Skierka |website=www.speciesfungorum.org |access-date=27 October 2022 |archive-date=9 October 2023 |archive-url=https://web.archive.org/web/20231009003036/https://www.speciesfungorum.org/Names/Names.asp?strGenus=Skierka |url-status=live }}</ref>
*[[Sphaerophragmiaceae]]
*[[Tranzscheliaceae]]<ref name = A&M2021/>
*([[Uropyxidaceae]])
*[[Zaghouaniaceae]] (incorporating [[Mikronegeriaceae]])<ref name = A&M2021>{{cite journal | pmc=8165960 | date=2021 | last1=Aime | first1=M. C. | last2=McTaggart | first2=A. R. | title=A higher-rank classification for rust fungi, with notes on genera | journal=Fungal Systematics and Evolution | volume=7 | pages=21–47 | doi=10.3114/fuse.2021.07.02 | pmid=34124616 }}</ref>
*mitosporic Pucciniales and ''[[incertae sedis]]''
}}

'''Rusts''' are [[fungal plant pathogen]]s of the order '''Pucciniales''' (previously known as '''Uredinales''') causing [[plant fungal disease]]s.

An estimated 168 rust [[genera]] and approximately 7,000 species, more than half of which belong to the genus ''[[Puccinia]]'', are currently accepted.<ref name="How many rust species exist?">{{cite book|last=Mohanan|first=C.|title=Rust Fungi of Kerala |publisher=Kerala Forest Research Institute |location=Kerala, India |year=2010 |pages=148 |isbn=978-81-85041-72-8}}
</ref> Rust fungi are highly specialized plant pathogens with several unique features. Taken as a group, rust fungi are diverse and affect many kinds of plants. However, each species has a range of hosts and cannot be transmitted to non-host plants. In addition, most rust fungi cannot be [[microbial culture|grown easily in pure culture]].

Most species of rust fungi are able to [[Heteroecious|infect two different plant hosts]] in different stages of their life cycle, and may produce up to five [[Morphology (biology)|morphologically]] and [[cytologically]] distinct [[spore]]-producing structures viz., [[spermogonia]], [[aecia]], [[uredinium|uredinia]], [[Telium|telia]], and [[basidia]] in successive stages of reproduction.<ref>{{Cite book|title=eLS|last1=Kolmer|first1=James A|last2=Ordonez|first2=Maria E|last3=Groth|first3=James V|date=2001|publisher=John Wiley & Sons, Ltd|isbn=9780470015902|language=en|doi=10.1002/9780470015902.a0021264|s2cid=1434349 }}</ref>  Each spore type is very host-specific, and can typically infect only one kind of plant.

Rust fungi are [[obligate parasite|obligate plant pathogen]]s that only infect living plants. Infections begin when a spore lands on the plant surface, germinates, and invades its host. Infection is limited to plant parts such as leaves, petioles, tender shoots, stem, fruits, etc.<ref name="How many rust species exist?"/> Plants with severe rust infection may appear stunted, [[chlorotic]] (yellowed), or may display signs of infection such as rust fruiting bodies. Rust fungi grow [[intracellular]]ly, and make spore-producing fruiting bodies within or, more often, on the surfaces of affected plant parts.<ref name="How many rust species exist?"/>  Some rust species form perennial systemic infections that may cause plant deformities such as growth retardation, [[witch's broom]], stem canker, [[gall]]s, or hypertrophy of affected plant parts.

Rusts get their name because they are most commonly observed as deposits of powdery [[rust]]-coloured or brown spores on plant surfaces. The Roman agricultural festival [[Robigalia]] (April 25) has ancient origins in combating wheat rust.<ref name="Evans 2007 p. ">{{cite book | last=Evans | first=R. | title=Utopia Antiqua: Readings of the Golden Age and Decline at Rome | publisher=Taylor & Francis | year=2007 | isbn=978-1-134-48787-5 | url=https://books.google.com/books?id=0YWCAgAAQBAJ | access-date=2018-01-12 | archive-date=2023-10-09 | archive-url=https://web.archive.org/web/20231009003026/https://books.google.com/books?id=0YWCAgAAQBAJ | url-status=live }}</ref>

==Impacts==
{{More citations needed section|date=October 2023}}

Rusts are among the most harmful pathogens to agriculture, horticulture and forestry. Rust fungi are major concerns and limiting factors for successful cultivation of agricultural and forest crops.{{Citation needed|date=October 2023}} White pine blister rust, wheat stem rust, soybean rust, and coffee rust are examples of notoriously damaging threats to economically important crops.<ref name="How many rust species exist?"/> Climate change may increase the prevalence of some rust species while causing others to decline through increased {{CO2}} and O<sub>3</sub>, changes to temperature and humidity, and enhanced spore dispersal due to more frequent extreme weather events.<ref>{{Cite journal |last=Helfer |first=Stephan |date=2013-10-30 |title=Rust fungi and global change |journal=New Phytologist |volume=201 |issue=3 |pages=770–780 |doi=10.1111/nph.12570 |pmid=24558651 |issn=0028-646X |doi-access=free }}</ref>

==Life cycle==
All rusts are obligate or biotrophic [[parasite]]s, meaning that they require a living host to complete their life cycle. They generally do not kill the host plant but can severely reduce growth and yield.<ref name="csldiagnostics.co.uk">Central Science Laboratory. (2006). Plant Healthcare: Rusts [Fact Sheet]. Retrieved from www.csldiagnostics.co.uk</ref> [[Cereal crops]] can be devastated in one season; oak trees infected in the main stem within their first five years by the rust ''[[Cronartium quercuum]]'' often die.<ref>{{cite web|url=http://www.backyardnature.net/f/rusts.htm|title=Rust Fungi|website=www.backyardnature.net|access-date=2010-08-06|archive-date=2010-09-17|archive-url=https://web.archive.org/web/20100917143359/http://backyardnature.net/f/rusts.htm|url-status=live}}</ref>

[[File:Modell von Puccinia graminis (Getreiderost) -Osterloh- -Brendel 10 h, 2-.jpg|thumb|Germinating urediniospore of ''[[Puccinia graminis]]'', model from the late 19th century, [[Botanical Museum Greifswald]]]]

Rust fungi can produce up to five spore types from corresponding fruiting body types during their life cycle, depending on the species. Roman numerals have traditionally been used to refer to these morphological types.

*0-'''[[Pycniospores]]''' ([[Spermatia]]) from [[Pycnidia]]. These serve mainly as [[haploid]] [[gamete]]s in [[heterothallic]] rusts.
*I-'''[[Aeciospores]]''' from Aecia. These serve mainly as non-repeating, [[dikaryotic]], asexual spores, and go on to infect the primary host.
*II-'''[[Urediniospores]]''' from [[Uredia]] ([[Uredinia]]). These serve as repeating dikaryotic vegetative spores. These spores are referred to as the repeating stage because they can cause auto-infection on the primary host, re-infecting the same host on which the spores were produced. They are often profuse, red/orange, and a prominent sign of rust disease.
*III-'''[[Teliospores]]''' from Telia. These dikaryotic spores are often the survival/[[overwintering]] stage of the life cycle. They usually do not infect a plant directly; instead they germinate to produce basidia and basidiospores. 
*IV-'''[[Basidiospores]]''' from [[Teliospores]]. These windborne haploid spores often infect the alternate host in Spring.<ref name="Schumann, G. 2010">Schumann, G. & D'Arcy, C. (2010). Essential plant pathology. APS Press</ref><ref>Scott, K.J, & Chakravorty, A.K., (1982), The Rust fungi. Academic Press.</ref> They are rarely observed outside of the [[laboratory]].

Rust fungi are often categorized by their life cycle. Three basic types of life cycles are recognized based on the number of spore types as '''macrocyclic''', '''demicyclic''', and '''microcyclic'''.<ref name="How many rust species exist?"/> The macrocyclic life cycle has all spore states, the demicyclic lacks the uredinial state, and the microcyclic cycle lacks the basidial, [[pycnia]]l, and the aecial states, thus possess only uredinia and telia.  Spermagonia may be absent from each type but especially the microcyclic life cycle.  In macrocyclic and demicyclic life cycles, the rust may be either host alternating ([[heteroecious]]) (i.e., the aecial stage is on one kind of plant but the [[telial stage]] on a different and unrelated plant), or single-host ([[autoecious]]) (i.e., the aecial and telial states on the same plant host).<ref name="How many rust species exist?"/> [[Heteroecious]] rust fungi require two unrelated hosts to complete their life cycle, with the primary host being infected by aeciospores and the alternate host being infected by basidiospores. This can be contrasted with an autoecious fungus, such as ''[[Puccinia porri]]'', which can complete all parts of its life cycle on a single host species.<ref name="Schumann, G. 2010"/> Understanding the life cycles of rust fungi allows for proper disease management.<ref name="Peterson, R. 1974">Peterson, R., (1974). The Rust Fungus Life Cycle. The Botanical Review. 40(4), 453-513.</ref>

==Host plant–rust fungus relationship==
There are definite patterns of relationship with host plant groups and the rust fungi that parasitize them. Some genera of rust fungi, especially ''[[Puccinia]]'' and ''[[Uromyces]]'', comprise species that are capable of parasitizing plants of many families.{{Citation needed|date=October 2023}} Other rust genera appear to be restricted to certain plant groups.{{Citation needed|date=October 2023}} Host restriction may, in [[heteroecious]] species, apply to both phases of life cycle or to only one phase.<ref name="How many rust species exist?"/> As with many pathogen/host pairs, rusts are often in [[Gene-for-gene interactions in rust fungi|gene-for-gene relationships with their plants]]. This rust-plant gene-for-gene interaction differs somewhat from [[gene-for-gene relationship|other gene-for-gene situations]] and has its own quirks and [[agronomy|agronomic]] significance. Rust fungi decrease photosynthesis and elicit the emissions of different stress volatiles with increasing severity of infection.<ref>{{cite journal |last1=Sulaiman Eve |first1=Hassan Y |last2=Runno-Paurson |last3=Kaurilind |first3=Eve |last4=Niinemets |first4=Ülo |title=Differential impact of crown rust (''Puccinia coronata'') infection on photosynthesis and volatile emissions in the primary host ''Avena sativa'' and the alternate host ''Rhamnus frangula'' |journal=Journal of Experimental Botany |date=2023 |volume=74 |issue=6 |pages=2029–2046 |doi=10.1093/jxb/erad001|pmid=36610799 }}</ref>

==Infection process==
The spores of rust fungi may be [[Biological dispersal#Types of dispersal|dispersed by]] wind, water or [[insect vector]]s.<ref>Craigie, J.H. (1931). ''Phytopathology'', 21,1001</ref> When a spore encounters a susceptible plant, it can germinate and infect plant tissues. A rust spore typically germinates on a plant surface, growing a short hypha called a [[germ tube]]. This germ tube may locate a [[stoma]] by a touch responsive process known as [[thigmotropism]]. This involves orienting to ridges created by [[Epidermis (botany)|epidermal cells]] on the leaf surface, and growing directionally until it encounters a stoma.<ref>Dickinson, M. Molecular Plant Pathology. 2003.</ref>[[File:rust attacking stoma.jpg|thumb|Rust hypha attacking stoma (1600x magnification)]] Over the stoma, a [[hypha]]l tip produces an infection structure called an [[appressorium]]. From the underside of an appressorium, a slender hypha grows downward to infect plant cells.<ref>Deising, H. B., S. Werner, and M. Wernitz, The role of fungal appressoria in plant infection. Microbes Infect, 2000. 2(13): pp. 1631–41.</ref> It is thought that the whole process is mediated by stretch-sensitive [[calcium channel|calcium ion channels]] located in the tip of the hypha, which produce electric currents and alter [[gene expression]], inducing appressorium formation.<ref>Zhou, X. L., et al., A mechanosensitive channel in whole cells and in membrane patches of the fungus Uromyces. Science, 1991. 253(5026): p. 1415.</ref>

Once the fungus has invaded the plant, it grows into plant [[mesophyll]] cells, producing specialized hyphae known as [[haustorium|haustoria]]. The haustoria penetrate [[cell wall]]s but not [[cell membrane]]s: plant cell membranes invaginate around the main haustorial body forming a space known as the ''extra-haustorial matrix''. An [[iron]]- and [[phosphorus]]-rich neck band bridges the plant and fungal membranes in the space between the cells for water flow, known as the [[apoplast]], thus preventing the [[nutrient]]s reaching the plant's cells. The haustorium contains [[amino acid transporter|amino acid-]] and [[hexose transporter|hexose sugar-]] transporters and [[H+ ATPase|H<sup>+</sup>-ATPases]] which are used for [[active transport]] of nutrients from the plant, nourishing the fungus.<ref>Voegele, R. T., and K. Mendgen, Rust haustoria: nutrient uptake and beyond. New Phytologist, 2003. 159(1): pp. 93–100.</ref> The fungus continues growing, penetrating more and more plant cells, until [[sporulation|spore growth]] occurs. The process repeats every 10–14 days, producing numerous spores that can be spread to other parts of the same plant, or to new hosts.

==Common rust fungi in agriculture==
<ref name="Schumann, G. 2010"/><ref name="Peterson, R. 1974"/><ref>Cornell University. (2010). Daylily rust: ''Puccinia hemerocallidis'' [Fact sheet]. Retrieved from http://plantclinic.cornell.edu {{Webarchive|url=https://web.archive.org/web/20100818215406/http://plantclinic.cornell.edu/ |date=2010-08-18 }}</ref>
*[[White Pine Blister Rust|''Cronartium ribicola'']] (white pine blister rust); the primary hosts are [[Ribes|currants]], and [[Pinus classification|white pines]] the secondary. Heterocyclic and macrocyclic
*''[[Gymnosporangium juniperi-virginianae]]'' (cedar-apple rust); ''[[Juniperus virginiana]]'' is the primary ([[teliospore|telial]]) host and [[apple]], [[pear]] or [[Crataegus|hawthorn]] is the secondary ([[aecial]]) host. Heteroecious and demicyclic
*''[[Hemileia vastatrix]]'' (coffee rust); primary host is coffee plant; unknown alternate host. Heteroecious
*''[[Phakopsora meibomiae]]'' and ''[[Phakopsora pachyrhizi|P. pachyrhizi]]'' ([[Asian soybean rust|soybean rust]]); primary host is soybean and various legumes. Unknown alternate host. Heteroecious
*''[[Puccinia coronata]]'' (crown rust of oats and ryegrass); oats are the primary host; ''[[Rhamnus (genus)|Rhamnus]] spp.'' (Buckthorn) is alternate host. Heteroecious and macrocyclic
*''[[Puccinia graminis|P. graminis]]'' (stem rust of wheat and Kentucky bluegrass, or black rust of cereals); primary hosts include: Kentucky bluegrass, barley, and wheat; [[Berberis vulgaris|Common barberry]] is the alternate host. Heteroecious and macrocyclic
*''[[Puccinia hemerocallidis|P. hemerocallidis]]'' (daylily rust); daylily is primary host; ''[[Patrinia]] sp'' is alternate host. Heteroecious and macrocyclic
*''[[Puccinia kuehnii|P. kuehnii]]'' (orange rust of sugarcane)
*''[[Puccinia melanocephala|P. melanocephala]]'' (brown rust of sugarcane)
*''[[Puccinia porri|P. porri]]'' (leek rust); [[Autoecious]]
*''[[Puccinia sorghi|P. sorghi]]'' (common rust of corn)<ref>{{Cite journal|year=1967|last1=Hooker|first1=Arthur L|title=The Genetics and Expression of Resistance in Plants to Rusts of the Genus Puccinia|volume=5|issue=1|pages=163–178|journal=Annu. Rev. Phytopathol.|doi=10.1146/annurev.py.05.090167.001115}}</ref>
*''[[Puccinia striiformis|P. striiformis]]'' (yellow rust) of cereals
*''[[Puccinia triticina|P. triticina]]'' (brown wheat rust) in grains
*''[[Uromyces appendiculatus]]'' (bean rust) in common bean (''[[Phaseolus vulgaris]]'')<ref>{{Cite journal |pmc = 5295601|year = 2016|last1 = Hurtado-Gonzales|first1 = O. P.|title = Fine Mapping of Ur-3, a Historically Important Rust Resistance Locus in Common Bean|journal = G3: Genes, Genomes, Genetics|volume = 7|issue = 2|pages = 557–569|last2 = Valentini|first2 = G.|last3 = Gilio|first3 = T. A.|last4 = Martins|first4 = A. M.|last5 = Song|first5 = Q.|last6 = Pastor-Corrales|first6 = M. A.|pmid = 28031244|doi = 10.1534/g3.116.036061}}</ref>

==Management==
===Research===
Efforts to control rusts began to be scientifically based in the 20th century.<ref name="Staples-2000">{{cite journal | year=2000 | issue=1 | volume=38 | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | first=Richard | s2cid=4861612 | pmid=11701836 | pages=49–69 | doi=10.1146/annurev.phyto.38.1.49 | issn=0066-4286 | journal=[[Annual Review of Phytopathology]] | title=Research on the Rust Fungi During the Twentieth Century | last=Staples}}</ref> [[Elvin C. Stakman]] initiated the scientific study of [[host resistance]], which had heretofore been poorly understood and handled by individual growers as part of the [[plant breeding|breeding process]].<ref name="Staples-2000" /> Stakman was followed by [[H. H. Flor]]'s extensive discoveries of rust genetics.<ref name="Staples-2000" /> In order to study rust [[metabolism|metabolics]], Tervet ''et al.'', 1951 developed the {{Vanchor|Cyclone Separator}}.<ref name="Staples-2000" /> The cyclone separator uses the [[cyclonic separation]] mechanism to allow the mechanised collection of spores for study – Cherry & Peet 1966's improved version gathers even more efficiently.<ref name="Staples-2000" /> This device was first put to work testing the composition of the spores themselves, especially substances coating the outside of the spores which [[quorum sensing|signal population density]].<ref name="Staples-2000" /> When detected they help prevent crowding.<ref name="Staples-2000" />

[[Gene cloning]] and other methods of [[genetic engineering]] can provide a much wider range of [[R gene]]s and other sources of rust resistance – with reduced delay before deployment – if [[regulation of genetic engineering]] permits.<ref name="Reveal rust R genes">{{Cite journal|journal=Plant Biotechnology Journal|year=2023|pages=1938–1951|volume=21|issue=10|last1=Dracatos|first1=Peter M.|last2=Lu|first2=Jing|last3=Sánchez-Martín|first3=Javier|last4=Wulff|first4=Brande B.H.|s2cid=260201756|pmid=37494504|doi=10.1111/pbi.14106|title=Resistance that stacks up: engineering rust and mildew disease control in the cereal crops wheat and barley|pmc=10502761 }}</ref>

===Control===
{{More citations needed section|date=October 2023}}

The control methods of rust fungus diseases depend largely on the life cycle of the particular pathogen. The following are examples of disease management plans used to control macrocyclic and demicyclic diseases:

Macrocyclic disease: Developing a management plan for this type of disease depends largely on whether the [[urediniospore]]s (rarely termed the "repeating stage") occur on the [[crop|economically important host plant]] or the [[alternate host]].{{Citation needed|date=September 2023}} For example, the repeating stage in [[white pine blister rust]] disease does not occur on white pines but on the alternate host, ''[[Ribes]]'' spp. During August and September ''Ribes'' spp. give rise to [[teliospore]]s which infect white pines. Removal of the alternate host disrupts the life cycle of the rust fungi ''[[Cronartium ribicola]]'', preventing the formation of basidiospores which infect the primary host. Although spores from white pines cannot infect other white pines, survival spores may overwinter on infected pines and reinfect ''Ribes'' spp. the following season. Infected tissue is removed from white pines and strict quarantines of ''Ribes'' spp. are maintained in high risk areas.{{Citation needed|date=September 2023}}

''[[Puccinia graminis]]'' is a macrocyclic [[heteroecious]] fungus that causes wheat stem rust disease.{{Citation needed|date=September 2023}} The sexual stage in this fungus occurs on the alternate host – [[barberry]] – and not wheat. The durable spore type produced on the alternate host allows the disease to persist in wheat even in more inhospitable environments. Planting resistant crops will prevent disease, however, virulence mutations will give rise to new strains of fungi that overcome plant resistance.{{Citation needed|date=September 2023}} Although the disease cannot be stopped by removal of the alternate host, the life cycle is disrupted and the [[rate of evolution]] is decreased because of reduced [[genetic recombination]]. This allows resistance bred crops to remain effective for a longer period of time.<ref name="Schumann, G. 2010"/><ref name="Marsalis, M. 2006">Marsalis, M. & Goldberg, N. (2006). Leaf, Stem, And Stripe Rust Diseases of Wheat. [Fact sheet]. New Mexico State University. http://pubs.nmsu.edu/_a/A415/ {{Webarchive|url=https://web.archive.org/web/20221127075223/https://pubs.nmsu.edu/_a/A415/ |date=2022-11-27 }}</ref>

Demicyclic disease: Because there is no repeating stage in the life cycle of demicyclic fungi, removal of the primary or the alternate host will disrupt the disease cycle.{{Citation needed|date=September 2023}} This method, however, is not highly effective in managing all demicyclic diseases. Cedar-apple rust disease, for example, can persist despite removal of one of the hosts since spores can be disseminated from long distances. The severity of cedar-apple rust disease can be managed by removal of basidiospore producing galls from junipers or the application of protective fungicides to junipers.<ref>Wallis, C. & Lewandowski, D. (2008). Cedar Rust Diseases of Ornamental Plants. [Fact Sheet]. Ohio State University. https://woodlandstewards.osu.edu/sites/woodlands/files/d6/files/pubfiles/3055%20cedar%20rust.pdf {{Webarchive|url=https://web.archive.org/web/20210107071958/https://woodlandstewards.osu.edu/sites/woodlands/files/d6/files/pubfiles/3055%20cedar%20rust.pdf |date=2021-01-07 }}</ref>

====Home control====
Rust diseases are very hard to treat. [[Fungicide]]s, such as [[Mancozeb]], may help but may never eradicate the disease.{{Citation needed|date=September 2023}} Some organic preventative solutions are available and sulphur powder is known to stop spore [[germination]]. High standards of [[hygiene]], good soil drainage, and careful watering may minimize problems. Any appearance of rust must be immediately dealt with by removing and burning all affected leaves.{{Citation needed|date=October 2023}} [[Composting]], or leaving infected vegetation on the ground, will spread the disease.{{Citation needed|date=October 2023}}

====Commercial control====
In some large acreage crops, fungicides are applied by air. The process is expensive and fungicide application is best reserved for seasons when foliar diseases are severe. Research indicates, the higher the foliar disease severity, the greater the return from the use of fungicides.<ref>{{cite web|url=http://www.stopsoybeanrust.com/viewStory.asp?StoryID=1140|title=Stopsoybeanrust.com|website=www.stopsoybeanrust.com|access-date=2010-08-06|archive-date=2018-06-12|archive-url=https://web.archive.org/web/20180612143153/http://www.stopsoybeanrust.com/viewStory.asp?StoryID=1140|url-status=live}}</ref> Southern corn rust disease, can be confused with common rust. Southern rust's distinguishing characteristic is that pustules form mostly on the upper leaf surface and spores are more orange in color. Southern rust spreads more quickly and has a higher economic impact when hot, humid weather conditions persist. Timely fungicide applications to control southern rust are more crucial than with common rust.<ref>{{Cite web|url=https://www.channel.com/en-us/agronomy/common-corn-rust.html|title=Common Corn Rust|website=www.channel.com|access-date=2019-12-16|archive-date=2019-12-16|archive-url=https://web.archive.org/web/20191216180933/https://www.channel.com/en-us/agronomy/common-corn-rust.html|url-status=live}}</ref>

A variety of preventative methods can be employed for rust diseases:
* High moisture levels may exacerbate rust disease symptoms. The avoidance of overhead watering at night, using drip irrigation, reducing crop density, and using fans to circulate air flow may decrease disease severity.
* The use of rust-resistant plant varieties
* Crop rotation can break the disease cycle because many rusts are host-specific and do not persist long without their host.
* Inspection of imported plants and cuttings for symptoms. It is important to continually inspect the plants because rust diseases have a latent period (plant has the disease but shows no symptoms).
* Use of disease-free seed can reduce incidence for some rusts<ref name="Marsalis, M. 2006"/>

===Host plants affected===
It is probable that most plant species are affected by some species of rust.{{Citation needed|date=October 2023}} Rusts are often named after a host species that they infect. For example; ''[[Puccinia xanthii]]'' infects the flowering plant cocklebur (''[[Xanthium]]''). Recently, a total of 95 rust fungi belonging to 25 genera associated with 117 forest plant species belonging to 80 host genera under 43 host families were reported from the [[Western Ghats]], [[Kerala]], [[India]].<ref name="How many rust species exist?"/> Rust fungi include:
{{Columns-list|colwidth=25em|
* ''[[Aecidium]]''
* ''[[Cerotelium]]''
* ''[[Chaconia (fungus)|Chaconia]]''
* ''[[Coleosporium]]''
* ''[[Crossopsora]]''
* ''[[Didymopsorella]]''
* ''[[Hamspora]]''
* ''[[Hapalophragmidium]]''
* ''[[Hemileia]]''
* ''[[Kernkampella]]''
* ''[[Kuehneola]]''
* ''[[Kweilingia]]''
* ''[[Macabuna]]''
* ''[[Maravalia]]''
* ''[[Melampsora]]''
* ''[[Olivea]]''
* ''[[Physopella]]''
* ''[[Puccinia]]''
* ''[[Ravenelia]]''
* ''[[Uraecium]]''
* ''[[Uredo]]''
* ''[[Uredopeltis]]''
* ''[[Uromyces]]''
* ''[[Xenostele]]''
* ''[[Zaghouania]]''
}}

Rust infected host genera include:<ref name="How many rust species exist?"/> 
{{Columns-list|colwidth=20em|
* ''[[Acacia]]''
* ''[[Acalypha]]''
* ''[[Ageratina]]''
* ''[[Albizia]]''
* ''[[Arundinaria]]''
* ''[[Bambusa]]''
* ''[[Bidens]]''
* ''[[Blepharis]]''
* ''[[Bombax]]''
* ''[[Bridelia]]''
* ''[[Callicarpa]]''
* ''[[Canarium]]''
* ''[[Canthium]]''
* ''[[Catunaragam]]''
* ''[[Cinnamomum]]''
* ''[[Cissus]]''
* ''[[Cleistanthus]]''
* ''[[Clerodendron]]''
* ''[[Coffea]]''
* ''[[Coix]]''
* ''[[Cosmostigma]]''
* ''[[Crotalaria]]''
* ''[[Dalbergia]]''
* ''[[Dendrocalamus]]''
* ''[[Derris]]''
* ''[[Diospyros]]''
* ''[[Dipterocanthus]]''
* ''[[Elaeagnus]]''
* ''[[Elephantopus]]''
* ''[[Elettaria]]''
* ''[[Eragrostis]]''
* ''[[Euphorbia]]''
* ''[[Ficus]]''
* ''[[Flacourtia]]''
* ''[[Grewia]]''
* ''[[Holarrhena]]''
* ''[[Holoptelia]]''
* ''[[Hypericum]]''
* ''[[Ichnocarpus]]''
* ''[[Ischaemum]]''
* ''[[Jasminum]]''
* ''[[Justicia (plant)|Justicia]]''
* ''[[Loesneriella]]''
* ''[[Luvunga]]''
* ''[[Meiogyne]]''
* ''[[Meliosma]]''
* ''[[Mimusops]]''
* ''[[Morus (plant)|Morus]]''
* ''[[Neolitzea]]''
* ''[[Ocimum]]''
* ''[[Olea]]''
* ''[[Oxalis]]''
* ''[[Pavetta]]''
* ''[[Persicaria]]''
* ''[[Phyllanthus]]''
* ''[[Plectranthus]]''
* ''[[Plumeria]]''
* ''[[Pongamia]]''
* ''[[Premna]]''
* ''[[Protasparagus]]''
* ''[[Rubus]]''
* ''[[Salix]]''
* ''[[Spondia]]''
* ''[[Strobilanthes]]''
* ''[[Strychnos]]''
* ''[[Tabernaemontana]]''
* ''[[Terminalia (plant)|Terminalia]]''
* ''[[Toddalia]]''
* ''[[Trichosanthes]]''
* ''[[Vernonia]]''
* ''[[Vigna]]''
* ''[[Wrightia]]''
* ''[[Xanthophyllum]]''
* ''[[Xylia]]''
* ''[[Ziziphus]]''
}}

Some of the better known hosts include:
{{Columns-list|colwidth=30em|
*''[[Arisaema triphyllum]]'', Jack-in-the-pulpit
*''Avena sativa'', [[Oat]]s
*''[[Berberis vulgaris]]'', Common barberry
*''[[Vicia faba]]'' - Broad beans
*''[[Coffea arabica]]'' - Coffee
*''[[Crataegus monogyna]]'' - Hawthorn
*[[Chrysanthemum]]
*''[[Quince|Cydonia]]'' - Quince
*''[[Euphorbia maculata]]'', Spotted Spurge
*''[[Fuchsia]] spp'', 
*[[Garlic]]
*''Hordeum vulgare'', [[Barley]]
*''Juniperus virginiana'', [[Juniperus virginiana|Red Cedar]] (Juniper apple disease)
*''[[Juniperus communis]]'' - Juniper
*''[[Allium ampeloprasum]]'' - Leek
*''[[Malus]]'' – Apple
*''[[Mentha piperita]]'' - Peppermint
*''[[Mespilus]]'' - Medlar
*[[Onion]]
*''[[Pelargonium]]''
*''[[Primula veris]]''
*''[[Primula vulgaris]]''
*''[[Pyrus]]'' - Pear
*''Rosa spp'', Roses
*''Triticum spp.'', [[Wheat]]
*''Oxalis spp.'', [[Oxalis]]
*''Secale cereale'', [[Rye]]
*''[[Senecio vulgaris]]'' -Common groundsel
*''[[Xanthium canadense]]'' Cocklebur
}}

==Hyperparasites of rusts==
In the family [[Sphaeropsidaceae]] of [[Sphaeropsidales]] fungi, species of the genus ''[[Darluca]]'' are [[hyperparasite]]s on rusts.<ref name="faculty.ucr.edu">[http://www.faculty.ucr.edu/~legneref/fungi/deuteromycota.htm faculty.ucr.edu] {{Webarchive|url=https://web.archive.org/web/20160303015458/http://www.faculty.ucr.edu/~legneref/fungi/deuteromycota.htm |date=2016-03-03 }} (retrieved December 2015)</ref>

==Gallery==
<gallery>
Image:Rust fungus (Uredinales) Pengo.jpg|Rust fungus on a leaf, under low magnification
Image:Rust fungus (Uredinales) pustules of urediniospores Pengo.jpg|Urediniospores of a rust fungus
Image:Rustinfection.JPG|Diagram representing the infection process of rust fungi
Image:Puccinia urticata rust fungus.JPG|Rust fungus, ''Puccinia urticata'' on the surface of a nettle leaf
Image:Rust on garlic plants2.jpg|Rust on onions
</gallery>

==See also==
{{Portal|Fungi}}
* [[Fungus]]
* [[Leaf rust (barley)]]
* [[Rust (programming language)]] (named after the Rust fungus<ref>{{Cite news |last=Thompson |first=Clive |date=14 February 2023 |title=How Rust went from a side project to the world's most-loved programming language |url=https://www.technologyreview.com/2023/02/14/1067869/rust-worlds-fastest-growing-programming-language/ |archive-url=https://web.archive.org/web/20230215000840/https://www.technologyreview.com/2023/02/14/1067869/rust-worlds-fastest-growing-programming-language/ |archive-date=15 February 2023 |url-status=live |work=[[MIT Technology Review]] |access-date=15 February 2023}}</ref>)
* [[Smut (fungus)]]
* [[Soybean rust]]
* [[Stem rust]]
* [[Wheat leaf rust]]

==References==
{{Reflist}}

==External links==
*{{Commons category-inline}}

{{Taxonbar|from=Q1130524}}
{{Authority control}}

{{DEFAULTSORT:Rust (Fungus)}}
[[Category:Pucciniales|.]]
[[Category:Fungal plant pathogens and diseases]]
[[Category:Basidiomycota]]