Urocystis agropyri
(flag smut of wheat)

Pictures

Picture	Title	Caption	Copyright
Title Symptoms Caption Urocystis agropyri (flag smut of wheat); symptoms on wheat. Copyright ©ISU	Symptoms	Urocystis agropyri (flag smut of wheat); symptoms on wheat.	©ISU
Title Symptoms on leaves, and spore balls Caption Urocystis agropyri (flag smut of wheat); infected leaves of Agropyron repens, x2 (left). Spore balls x430 (right). ©CMI Descriptions of Pathogenic Fungi and Bacteria No. 716. CAB International, Wallingford, UK. Copyright ©CABI BioScience	Symptoms on leaves, and spore balls	Urocystis agropyri (flag smut of wheat); infected leaves of Agropyron repens, x2 (left). Spore balls x430 (right). ©CMI Descriptions of Pathogenic Fungi and Bacteria No. 716. CAB International, Wallingford, UK.	©CABI BioScience
Title Spore balls close up Caption Urocystis agropyri (flag smut of wheat); spore balls, surface ornamentation. Original x1100. ©CMI Descriptions of Pathogenic Fungi and Bacteria No. 716. CAB International, Wallingford, UK. Copyright ©CABI BioScience	Spore balls close up	Urocystis agropyri (flag smut of wheat); spore balls, surface ornamentation. Original x1100. ©CMI Descriptions of Pathogenic Fungi and Bacteria No. 716. CAB International, Wallingford, UK.	©CABI BioScience

Identity

Preferred Scientific Name

• Urocystis agropyri (Preuss) A.A. Fisch. Waldh. 1867

Preferred Common Name

• flag smut of wheat

Other Scientific Names

• Polycystis agropyri (Preuss) Schroet. 1877
• Tuburcinia agropyri-campestris Massenot 1955
• Tuburcinia occulta var. agropyri (Preuss) Ellis 1879
• Tuburcinia tritici (Körn.) Liro 1922
• Turbucinia agropyri (Preuss) Liro 1922
• Uredo agropyri Preuss 1848
• Urocystis agropyri (Preuss) Schroet. 1869
• Urocystis agropyri-campestris (Massenot) H. Zogg 1986
• Urocystis preussii J.G. Kuhn 1874
• Urocystis tritici Körnicke 1877

International Common Names

• English: flag smut; leaf smut; stem smut; stripe smut
• Spanish: carbon de las hojas de la grama; carbon de las hojas del trigo; carbon del trigo; carbon foliar del trigo
• French: charbon des feuilles du blé; charbon des feuilles du chiendent; charbon du blé; charbon foliaire du blé

Local Common Names

• Germany: Brand, Blattstreifen-: Weizen; Brand, Stengel-: Weizen; Brand, Stengelstreifen-: Weizen
• India: patton ki kungi

EPPO code

• UROCAG (Urocystis agropyri)

Summary of Invasiveness

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Fungi
•         Phylum: Basidiomycota
•             Subphylum: Ustilaginomycotina
•                 Class: Ustilaginomycetes
•                     Order: Urocystidiales
•                         Family: Urocystidaceae
•                             Genus: Urocystis
•                                 Species: Urocystis agropyri

Notes on Taxonomy and Nomenclature

U. agropyri was the name given to a smut on leaves of weedy grasses, including Elymus (Agropyron) repens (Vánky, 1994). Wolff (1873) identified the fungus causing flag smut of wheat [Triticum aestivum] in Australia as the species Urocystis occulta (Wallr.) Rabenh ex Fuckel found on rye [Secale cereale] a few years earlier. Körnicke (1877) studied the spore morphology of this fungus on the Australian plants and determined that it differed from U. occulta sufficiently to warrant the introduction of the name Urocystis tritici. Subsequently, Fischer (1943), on the basis of morphology, and Fischer and Holton (1943), on the basis of the results of cross-inoculation tests, suggested that U. tritici was synonymous with U. agropyri. This species concept is in agreement with the general one for smut fungi proposed by Fischer and Shaw (1953). On the basis of variability in U. agropyri and U. tritici, Savile (1953) stated that it was impossible to disagree with Fischer's wide species concept. Because the epithet “agropyri" has priority over “tritici”, the correct name for the fungus, then, is that of the fungus described on grasses. Nevertheless, the name Urocystis agropyri (Preuss) Schroet., as used by Fischer and subsequently by others, is incorrect due to a misdesignation of the type (USDA/SMML, 2005); the authority should be cited as (Preuss) A.A. Fisch. Waldh. Other workers have differed from Fischer and treated the flag smut of wheat and that of grasses as separate species (Purdy, 1965; Vánky, 1994; Denchev, 2001; Vánky, 2007; Vánky and Shivas, 2008).

Description

Distribution

Urocystis tritici was first observed on wheat [Triticum aestivum], an introduced Eurasian crop, in Australia in the mid-nineteenth century (McAlpine, 1910), whereas U. agropyri was described somewhat earlier in Germany (Vánky, 1994). U. agropyri has been reported as the flag smut on wheat (Triticum spp.) and other Poaceae from many countries on all inhabited continents (UK CAB International, 1991). As a seedborne and soilborne pathogen, it is endemic in localized areas where soil temperature and moisture are favourable for teliospore germination and subsequent infection of susceptible hosts. Line (1998) notes that the environmental conditions and agronomic practices favourable to the pathogen on wheat, only occur in limited parts of the world, and those only include some wheat-growing areas. In some countries from which it has been reported, such as Canada (Sansford et al., 1999), U. agropyri may be known only on grasses and not on wheat. Although it was already familiar as a species on Agropyron species (Sampson, 1940), the flag smut fungus was not reported on wheat in the UK until 1998 (Sansford et al., 1998).

Reports on the occurrence of either species, particularly on grass hosts, may vary in accuracy depending on the reporter’s ability to separate smut species on the basis of small morphological differences and to determine the identity of the host grasses.

According to the NPPO of Argentina, U. agropyri is no longer present in Argentina (SENASA, 2020. Communication to CABI. SENASA-Argentina, Buenos Aires, Argentina). A literature survey of the pest and consultation with plant pathologists at the National Institute of Agricultural Technology (INTA), Argentina, has established that U. agropyri has not been reported in the country for more than 40 years.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Introductions

Risk of Introduction

Rossman et al. (2006) placed U. agropyri in the category “Threat to Major Crop Plants” of North America. In contrast, neither U. agropyri nor Urocystis tritici appear as an invasive species in the ISSG database (ISSG, 2009). To a large extent, the risk of introduction of the smut depends on the taxonomy, that is, whether flag smut of wheat [Triticum aestivum] and some grasses is truly the same species as flag smut of other grasses. The risk to significant crops is from the “wheat isolates” of U. agropyri, otherwise known as U. tritici. If U. tritici is the same as the widely reported U. agropyri, U. agropyri is already present on all continents with wheat-growing areas (Purdy, 1965), and it may be difficult to exclude from additional areas due to its host range inclusive of many wild grasses. Purdy (1965) lists species of Aegilops, Agropyron, Elymus and Hordeum as having been determined by inoculation to be hosts of the wheat pathogen. U. agropyri in the restricted sense, as its host range is understood (Sampson and Watson, 1985; Vánky, 1994), is not a threat to cereals. Both smuts are seed and soil borne, causing systemic infections that can be perennial in weedy grasses, forage grasses or turfgrasses that are not grown as annuals. The spore balls are windborne (Purdy, 1965), but larger and presumably heavier, and so slower to spread than the single spores of other grass pathogens; local quarantines such as those imposed after an introduction in Mexico (Borlaug et al., 1946) may be successful.

PHYTOSANITARY RISK

Risk Criteria Category

Economic Importance Low
Distribution Worldwide
Seedborne Incidence Low
Seed Transmitted Yes
Seed Treatment Yes

Overall Risk Low

Habitat List

Hosts/Species Affected

Plants are initially attacked by U. agropyri at pre-emergence when seedlings are less than 10 mm long. Plants are affected from seedling stage to maturity. Under a wide and primarily morphological species concept for smut fungi (Fischer and Shaw, 1953), a large number of species in the grass subfamily Pooideae, in addition to the Triticum species, are reported to be attacked by U. agropyri in nature (Fischer, 1953; Zundel, 1953; Purdy, 1965; Duran, 1968; Hodges, 1970). Nevertheless, individual isolates show marked host specialization, and most wheat isolates will not infect other grass species (Mordue and Waller, 1981). Fischer and Holton (1943) found that some isolates from wheat in the USA differed in their ability to infect Agropyron and Elymus species. Currently, in Australia, grasses are not considered an important source of inoculum for flag smut on wheat (Vánky and Shivas, 2008). Despite the apparent host specialization, the following grass hosts have been successfully infected in artificial inoculation tests (Purdy, 1965) using isolates from wheat [Triticum aestivum]: Agropyron caninum [Elymus caninus]; Agropyron dasystachyum [Elymus lanceolatus]; Agropyrondesertorum; Agropyron elongatum [Thinopyrum elongatum]; Agropyron semicostatum; and Aegilops squarrosa. Rees and Platz (1973) obtained infection from a wheat isolate to Agropyron scabrum [Elymus scaber] and from that grass back to wheat. Conversely, Sampson and Watson (1985), using four inoculation methods, could not obtain infection by U. agropyri isolated from Agropyron repens [Elymus repens] in Canada on 47 other grasses, including A. dasystachyum, A. elongatum, several other Elymus species, and three cultivars of wheat.

Host Plants and Other Plants Affected

Growth Stages

Symptoms

List of Symptoms/Signs

Biology and Ecology

Fischer and Holton (1957) and Purdy (1965) summarized the life cycle, mode of penetration and spread, and ecological relationships of U. agropyri and Urocystis tritici, respectively.

Life Cycle and Transmission

The fungus is either 'seedborne' from spore balls containing teliospores that contaminate the seed surface or 'soilborne' from spore balls in the soil. Systemic mycelium may overwinter in infected wheat [Triticum aestivum] seedlings or survive continuously in crowns, rhizomes, leaves, etc., of perennial grasses (Smiley et al., 2005).

U. agropyri belongs to the 'seedling-infecting' group of smut fungi. Infection occurs before seedling emergence from the soil. Teliospores germinate to produce sporidia that fuse to form infection hyphae that infect young coleoptiles of hosts. Temperatures between 10 and 20°C, and moist soil favour the infection of wheat (Purdy, 1965).

According to Takahashi and Iwata (1964), hyphae penetrate through the epidermal cell walls of the coleoptile. After infection, the fungus grows both inter- and intra-cellularly until it begins to sporulate, initially in the leaf blades and then in the leaf sheath and all the other above-ground plant parts. Sporulation begins with the 'rounding up' of mycelial elements between the vascular tissue and the epidermis. These mycelial aggregations produce thick-walled teliospores and surrounding sterile cells. The sori containing the spore balls first appear as white streaks on the leaf at 6-10 weeks after planting and later change colour through grey to black. Infected plants may fail to produce seeds or have malformed inflorescences due to the pathogen’s growth and sporulation.

At harvest, sori on wheat plants are broken by drying out and the harvesting operations; spore balls are released and infest seeds and soil. The life cycle is completed when spores from one crop germinate and infect the developing seedlings of a new crop. Spores may be transported for long distances with seeds, on straw, or on farm machinery (Line, 1998). The smut spores can survive for 4 years in the soil and for up to 10 years under conditions of ideal seed storage (Neergaard, 1977). They are also able to survive passage through farm animals into manure (McAlpine, 1910).

According to El-Khadem et al. (1980), U. agropyri from wheat is heterothallic; monosporidial cultures did not form clamp connections. Only two different mating types were found among the monosporidial cultures, and successful matings formed dikaryotic infection hyphae and then teliospores.

Ecology

Spore germination and infection by U. agropyri in the pre-emergence stage of plant development is influenced to a considerable degree by plant exudates (Goel and Jhooty, 1987), other ecological factors (e.g. soil moisture, soil temperature, soil pH) and also by cultural practices such as planting date, seed depth and genetic resistance of the host variety (Purdy, 1965). The incidence of disease caused by U. agropyri is therefore highly variable in individual fields and agroclimatic zones in the same or different seasons.

In Australia, flag smut posed a serious threat to wheat in the 1920s, but with the release of several resistant cultivars its incidence rapidly declined. With widespread cultivation of susceptible wheat, there was a resurgence of the flag smut problem (cf. Platz and Rees, 1980). The release and use of the susceptible wheat cultivar, Rosella, resulted in the spread of flag smut in New South Wales (Ballantyne, 1993). In the Pacific North-West region of the USA, damage and distribution of flag smut increased after the adoption of deep seeding in early autumn planting and the release of several susceptible wheat cultivars between 1955 and 1971. However, renewed attention to the use of resistant varieties later mitigated the problem (Allan, 1976).

In India, the incidence of flag smut in wheat is limited to some north-western states such as Haryana, Himachal Pradesh, Indian Punjab and Rajasthan, because adequate summer rainfall and favourable soil temperatures needed for spore germination and subsequent infection by U. agropyri do not occur in other wheat-growing regions (Goel and Jhooty, 1985b).

Climate

Seedborne Aspects

Incidence

Seed lots of Agrostis spp., Elymus spp., Festuca spp., Hordeum vulgare (barley), Poa spp., Triticum aestivum (wheat) and other Triticum spp. can be contaminated with teliospores or spore balls of U. agropyri, released from infected leaves or plant parts (Neergaard, 1977; Richardson, 1990). These propagules can remain viable for several years (Purdy, 1965). Asaad and Abang (2009) report that, in more than 50,000 cereal seeds received from 41 countries and tested by the International Center for Agricultural Research in the Dry Areas (ICARDA) between 1995 and 2004, 0.02% of wheat and barley seeds were found to be infected with U.agropyri.

Effect on Seed Quality

The pathogen is a seed-surface contaminant and has not been reported as having any adverse effect on wheat seed appearance or germination. Seed inoculations with U. agropyri were reported to reduce germination of Poa pratensis seeds (Hodges, 1970).

Seed Transmission

It has been suggested that the development of flag smut in Australia in the nineteenth century and in the USA in the early twentieth century could be attributed to the introduction of the fungus on contaminated seeds (McAlpine, 1910; Purdy, 1965). Epidemiological knowledge of the pathogen suggests that this could well have happened. Seed infestation with dry teliospores of U. agropyri has been shown to be sufficient for creating an artificial epidemic of flag smut for reliable screening of wheat germplasm (Rewal et al., 1986). Flag smut incidence increases with an increase in inoculum load applied to the seeds (Goel and Jhooty, 1989). Seed inoculations of Poa pratensis resulted in coleoptile infection, followed by adult plant infection (Hodges, 1970). Fischer and Holton (1957) classified flag smut of wheat as a 'seedling-infecting smut'. Infection occurring in the pre-emergence phase of seedling growth originates either from seedborne inoculum (i.e. from the spores that contaminate the seed surface) or from soilborne inoculum (i.e. from the spores in the soil).

Quarantine regulations were issued in the early twentieth century in the USA to prevent further spread of the disease from the region where infested seed had been used (Anon., 1919; 1925; Purdy, 1965). Similar schemes are in operation in Belgium, the Netherlands, Germany, the UK and many other countries (Neergaard, 1977).

Seed Treatments

Copper carbonate was the first dry treatment used to control flag smut of wheat (Fischer and Holton, 1957). Effective control of flag smut of wheat originating from both seedborne and soilborne inoculum was achieved through seed treatment with quintozene (Yasu and Yoshino, 1963). With the advent of systemic fungicides, effective disease control without a marked reduction in seedling survival was obtained with benomyl, carboxin and oxycarboxin seed treatments (Metcalfe and Brown, 1969).

Current products for dry seed dressings include non-systemics such as copper carbonate and organomercurials. Systemics such as carboxin and oxycarboxin are also used (Neergaard, 1977). In addition, fenfuram, triadimefon, triadimenol and tebuconazole provide control of U. agropyri in the Indian subcontinent (Goel and Jhooty, 1985a; Tariq et al., 1992). Seed treatment with tebuconazole at 1.0, 1.5 and 2.0 g kg^-1, or carboxin and carbendazim at 2.0 and 2.5 g kg^-1 seeds reduced disease incidence in wheat (Kumar and Singh, 2004), as will tetramethyl thiuram disulphide (Thiram 75% DS) at 3 g/kg seed, thiophanate methyl (Topsin-M 70WP) at 1 and 2 g/kg seed, or a combination of tetramethyl thiuram disulphide and carboxin (Shekhawat et al., 2011). Flag smut of wheat has ceased to be a problem in the regions where seed treatment with systemics is routine practice for its control.

An alternative is solar energy treatment, which is practical in seasonally hot regions, such as the north-western plains of India. Seeds are soaked in water (1:1 w/v) in a galvanised tub which is tightly covered with a transparent polythene sheet and placed under the sun. Duhan and Beniwal (2004) placed such a tub under the sun in India for 6 hours (08.00-14.00) during September, and found that this gave more than 96% of loose smut.

Seed Health Tests

Asaad and Abang (2009) report the standard methods they used to assess the level of seed infection. Seed testing methods for the detection of fungi are presented by Mathur and Kongsdal (2003).

Pathway Causes

Pathway Vectors

Plant Trade

Impact Summary

Economic Impact

Reduced yield is the most significant reflection of losses due to U. agropyri in wheat [Triticum aestivum]. Infected plants usually represent a complete loss in yield (Purdy, 1965); the percentages of infected plants reported in commercial fields might therefore be regarded as a reliable measure of the economic importance of flag smut, either locally or regionally. Generally, losses from U. agropyri are discussed in terms of individual fields or localized areas of infection. Thus, although the economic impact of the disease on a region may be relatively small, the losses might be very significant to a farmer whose own crop is infected by flag smut. Losses of up to 100% are possible (Purdy, 1965).

It is difficult to evaluate the economic losses caused by U. agropyri in other grasses. However, Nus and Hodges (1990) reported that in Poa pratensis cv. Merion, flag smut infection decreased rhizome growth and increased tiller growth. 

In general, plants infected with U. agropyri are more susceptible to drought and other adverse conditions (Smiley et al., 2005). Thus there is an indirect, as well as a direct, loss of stand, resulting in significant damage to turf or losses in pasturage.

In the USA in the early 1960s, flag smut of wheat occurred in Klickitat, Walla Walla and Yakima counties of Washington State, and in Wasco and Umatilla counties of Oregon, where the incidence varied from trace levels to about 30% (Purdy and Allan, 1967). According to Nelson and Duran (1984), this disease was destructive in localized areas in south-central and south-eastern Washington. Wiese (1987) reports that flag smut of wheat once reduced yield by an average of 1% in the western USA, with individual losses ranging up to 50%.

In pre-partition Punjab (India), flag smut was reported to cause an annual loss of 15,000 tonnes of wheat (Wattspadwick, 1948). It was later recorded in a severe form in Himachal Pradesh (Singh and Sethi, 1975) and Rajasthan (Bhatnagar et al., 1978).

Beniwal (1992) reported 23-65% yield losses from flag smut infection in nine commercial wheat cultivars in the Indian state of Haryana. Tillering was reduced by 15-45%, plant height by 37-62%, earhead length by 28-46% and 1000 grain weight by 19-37%.

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Highly adaptable to different environments
• Long lived
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Host damage
• Negatively impacts agriculture
• Negatively impacts livelihoods

• Pathogenic

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field

Uses

Diagnosis

Detection and Inspection

Similarities to Other Species/Conditions

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

U. agropyri is soilborne and externally seedborne. Therefore, in the past, quarantine regulations on the movement of infested seed, chaff and farm machinery from endemic areas were established to restrict its spread (Anon., 1919; 1925; 1931; 1935; 1946; 1953; 1955). However, quarantine restrictions have been gradually lifted or relaxed because U. agropyri has now been reported from many agroclimatic regions worldwide (UK CAB International, 1991). Line (1998) argues that quarantines were, and are, not necessary for the control of flag smut of wheat [Triticum aestivum], because seed treatment, the use of resistant cultivars, and appropriate cultural methods can control the disease. Nevertheless, in Canada, where the fungus does not occur on wheat (Sansford et al., 1999), restrictions on importation of wheat from parts of the USA and from countries worldwide where “wheat strains” of U. agropyri occur are maintained (CFIA, 2008). The USA maintains quarantine measures on various articles of wheat or those made from wheat, such as seeds, plants, straw, etc., which may carry “foreign strains” of the flag smut pathogen that could be introduced (Anon., 2005).
 
Eradication 
 
Sufficiently long cycles of crop rotation may result in eradication of inoculum in the soil, but the smut spore balls are known to persist for several years (Purdy, 1965). Repeated planting of resistant varieties may have the same local effect; Purdy (1965) attributes the decline or disappearance of flag smut on wheat from parts of the USA to the use of resistant varieties.
 
Control
 
Cultural Control
 
Cultural practices and sanitary methods that tend to reduce inoculum, such as rotation with non-hosts, early fallow with thorough working of the soil, and burning stubble, are quite useful. Nevertheless, as Wiese (1987) indicates, spore balls are capable of surviving in soil for at least 3 years, so shorter rotations or fallow periods may only reduce the soilborne inoculum to some extent. Manipulation of planting time and depth, to conserve soil moisture and avoid soil temperatures that are favourable for spore germination and subsequent infection, can also be effective in disease control in specific areas. However, such measures may not be profitable because they may result in lower yields (Purdy, 1965). The disease is favoured when practices such as deep planting, shallow tillage and early-autumn planting are followed in areas where soil moisture is a limiting factor for wheat production (Line, 1998).
 
In Egypt, the 'afir method' of planting wheat is better than the 'herati method' (Jones and El Nasr, 1938) for control of flag smut in endemic areas. In the afir method, seed is planted in dry soils that are later irrigated, so that the inoculum is 'dormant' while seedlings are at a susceptible stage, whereas in "herati", seed is planted in moist soil, where spore inoculum is able to germinate and infect seedlings.
 
In Australia, Greenhalgh and Brown (1984) found that the incidence of flag smut was higher at -126 kPa than at -37 kPa; however, it was generally unaffected by the depth of sowing.
 
Although the effects of fertilizers on flag smut of wheat are complicated (Purdy, 1965), increased levels of nitrogen are known to favour the disease in turfgrasses (Smiley et al., 2005). In India, Kumar and Singh (2004) found that higher levels of nitrogen and phosphorus fertilizer, as well as the addition of poultry manure to the soil, reduced the level of the disease in wheat, although not to the low level obtained with seed treatments.
 
Host-Plant Resistance
 
Among all the cereal smuts, U. agropyri has shown the least tendency towards pathogenic specialization (Fischer and Holton, 1957). According to Hafiz (1986), only six races were reported, in all, from different countries. Some peculiar features in the life cycle of this fungus (e.g. production of fewer sporidia compared to related smut fungi, the absence of secondary sporidia, and sporidial fusions in situ) are probably responsible for limiting its variability (Nelson and Duran, 1984). As a consequence, resistance to flag smut has remained effective in Australia and elsewhere (Platz and Rees, 1980; Goel, 1992) and new races have not been detected (Line, 1998). Purdy (1965) and Line (1998) attribute disappearance of flag smut as a problem on wheat in parts of the USA primarily to the use of resistant varieties.
 
According to Johnson (1984), there is no evidence of genotype-specific pathogenicity of the type indicating a gene-for-gene relationship. Therefore, the incorporation of resistance into commercial cultivars offers prospects for continued effective disease management (Goel, 1992).
 
Chemical Control
 
Effective control of flag smut of wheat originating from both seedborne and soilborne inoculum was achieved through seed treatment with quintozene (Yasu and Yoshino, 1963). With the advent of systemic fungicides, effective disease control without a marked reduction in seedling survival was obtained with benomyl, carboxin and oxycarboxin seed treatments (Metcalfe and Brown, 1969).
 
Dry seed-dressing with non-systemics such as copper carbonate, and systemics such as carboxin, oxycarboxin and pyracarbolid have also been used (Neergaard, 1977). In addition, fenfuram, triadimefon, triadimenol and tebuconazole provide control of U. agropyri in the Indian subcontinent (Goel and Jhooty, 1985a; Tariq et al., 1992).
 
Flag smut of wheat has ceased to be a problem in the regions where seed treatment with systemics is a routine practice for the control of this disease and for loose smut (Ustilago tritici). As Loughman (1989) states concerning flag smut on wheat in Australia, seed treatment may be applied, not so much for the resulting increase in yield (of susceptible varieties), as to prevent an increase in the fungus population in the soil. A reduction in the use of seed treatment with fungicide is considered to be one factor in the increase of flag smut in the Near East and North Africa (Mamluk, 1998). The fungus readily produces significant amounts of long-lived inoculum from a small number of infected plants.

Gaps in Knowledge/Research Needs

The question of the number of distinct Urocystis species on Pooid grasses and cereals should be resolved by the use of molecular techniques, with the resulting data made publicly available for diagnostic purposes. Cross-inoculation tests of wheat [Triticum aestivum] and agriculturally important weedy grasses with molecularly characterized isolates from those species should clarify the possible or potential role of grasses in the epidemiology and spread of flag smut on wheat. 

References

Allan RE, 1976. Flag smut reaction in wheat: its genetic control and associations with other traits. Crop Science, 16(5):685-687

Alvarez MG, 1976. Primer catalogo de enfermedades de plantas Mexicanas. Fitofilo, 71:1-169

Anon., 1919. Federal Horticultural Board, United States Department of Agriculture, Quarantine on account of flag smut and take-all diseases. Notice of quarantine No. 39 (with regulations). United States Department of Agriculture, Service and Regulatory Announcements, 64:77-79.

Anon., 1925. Quarantine on account of the flag smut disease. Notice of quarantine No. 59. United States Department of Agriculture, Federal Horticultural Board leaflet.

Anon., 1931. Legislative and administrative measures, Mexico. International Bulletin of Plant Protection, 5:122-123.

Anon., 1935. List of insect pests and diseases prohibited by external quarantine legislation from importation into the USSR. USSR People's Commissariat Agriculture Section internal and external. Plant Quarantine, 2, Moscow

Anon., 1946. Plant Quarantine Import Restrictions, Iran. Service and Regulatory Announcements, Bureau of Entomology and Plant Protection, United States Department of Agriculture, 168:51-54.

Anon., 1953. Plant Quarantine Announcement 1953, Food and Agriculture Organization of the United Nations. FAO Plant Protection Bulletin, 1:158-159.

Anon., 1955. Plant Quarantine Announcements, Food and Agriculture Organization of the United Nations. FAO Plant Protection Bulletin, 3:110-111.

Anon., 2005. Foreign quarantine notices. United States Federal Register, 70. 8231-8233. [7 CFR Part 319.]

Asaad S, Abang MM, 2009. Seed-borne pathogens detected in consignments of cereal seeds received by the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria. International Journal of Pest Management, 55(1):69-77. http://journalsonline.tandf.co.uk/link.asp?id=100665

Ballantyne B, 1993. Reactions of wheat cultivars to flag smut in southern New South Wales. Australasian Plant Pathology, 22(3):100-104

Bansandrai AK, Sood AK, Sud AK, 1993. Prevalence of flag smut of wheat (Urocystis agropyri) in Himachal Pradesh. Plant Disease Research, 8(1):85

Beniwal MS, 1992. Effect of flag smut on yield and yield components of wheat varieties. Crop Research (Hisar), 5(2):348-351

Bhatnagar GC, Gupta RBL, Mishra VL, 1978. Effect of flag smut, caused by Urocystis agropyri on yield components of wheat cultivars in Rajasthan, India. Plant Disease Reporter, 62(4):348-350

Borlaug NE, Harrar JG, Stakman EC, 1946. Flag smut of wheat in Mexico. Phytopathology, 36:479

BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens. Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm

CFIA, 2008. Canadian Food Inspection Agency. Ottawa, Canada: Government of Canada. http://www.inspection.gc.ca/

Denchev CM, 2001. Class Ustomycetes (orders Tilletiales, Ustilaginales, and Graphiolales). Fungi Bulgaricae, 4:1-286

Dietrich W, Müller J, 2001. The rust fungi, smut fungi and downy mildews in the Czech part of KrusnT hory (Erzgebirge). Czech Mycology, 53(1):89-118; 41 ref

Duhan JC, Beniwal MS, 2004. Improved solar energy treatment for the control of loose smut, flag smut and karnal bunt diseases of wheat. Seed Research, 32(2):184-188

Duran R, 1968. Subterranean sporulation by two graminicolous smut fungi. Phytopathology, 58:390

El-Buni AM, Rattan SS, 1981. Check list of Libyan fungi. Tripoli, Lebanon: Al Faateh University Faculty of Science, Department of Botany, 169 pp

El-Khadem M, Omar RA, Kamel AH, El-Naga SAA, 1980. Physiologic and pathogenic races of Urocystis agropyri. Phytopathologische Zeitschrift, 98(3):203-209

EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm

Fischer GW, 1943. Some evident synonymous relationships in certain graminicolous smut fungi. Mycologia, 35:610-619

Fischer GW, 1953. Manual of the North American Smut Fungi. New York, USA: The Ronald Press Company

Fischer GW, Holton CS, 1943. Studies on the susceptibility of forage grasses to cereal smut fungi. IV. Cross inoculation experiments with Urocystis tritici, U. occulta and U. agropyri. Phytopathology, 33:910-921

Fischer GW, Holton CS, 1957. Biology and control of the smut fungi. New York, USA: The Ronald Press Company

Fischer GW, Shaw CG, 1953. A proposed species concept in the smut fungi with application to North American species. Phytopathology, 43:181-188

Goel RK, 1992. Flag smut of wheat. Indian Journal of Mycology and Plant Pathology, 22(2):113-124

Goel RK, Jhooty JS, 1985. Chemical control of flag smut of wheat caused by Urocystis agropyri. Indian Phytopathology, 38(4):749-751

Goel RK, Jhooty JS, 1985. Effect of temperature and pre-soaking on teliospore germination in Urocystis agropyri causing flag smut of wheat. Indian Journal of Plant Pathology, 3(1):134-137

Goel RK, Jhooty JS, 1987. Stimulation of germination in teliospores of Urocystis agropyri by volatiles from plant tissues. Annals of Applied Biology, 111(2):295-300

Goel RK, Jhooty JS, 1989. Some factors affecting the incidence of flag smut of wheat. Indian Journal of Agricultural Research, 23(4):200-204

Greenhalgh FC, Brown JS, 1984. A method for determining the reactions of wheat breeding lines to flag smut. Australasian Plant Pathology, 13(3):36-38

Guo L, 2005. Ustilaginales. In: Fungi of Northwestern China [ed. by Zhuang, W. Y.]. Ithaca, New York, USA: Mycotaxon, Ltd., 291-304

Hafiz A, 1986. Plant Diseases. Islamabad, Pakistan: Pakistan Agricultural Research Council

Hodges CF, 1970. Comparative morphology and development of Poa pratensis infected by Ustilago striiformis and Urocystis agropyri. Phytopathology, 60:1794-1797

Hori S, 1907. Seed infection by smut fungus of cereals. Imperial Central Agricultural Experiment Station Bulletin, Japan, 1:163-176

Humphrey HB, Johnson AG, 1919. Take all and flag smut, two wheat diseases new to the United States. Farmers' Bulletin, 1063. USA: US Department of Agriculture

Ibrahim GH, 2007. Biological control of ryegrass in wheat fields by new isolate of Urocystis agropyri. Plant Pathology Journal (Faisalabad), 6(3):260-265. http://www.ansinet.org/ppj

ISSG, 2009. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database

Johnson R, 1984. A critical analysis of durable resistance. Annual Review of Phytopathology, 22:309-330

Jones GH, El Nasr A El GS, 1938. Control of four smut diseases by regulation of planting method under irrigation. Nature, 142:917-918

Kumar VR, Bhim Singh, 2004. Management of flag smut in wheat. Annals of Plant Protection Sciences, 12(1):92-95

Körnicke FA, 1877. Mykologische beitrage. Hedwigia, 16:33-40

Line RF, 1998. Quarantines for the control of flag smut of wheat: are they effective or necessary? In: Bunts and smuts of wheat: an international symposium. Raleigh, North Carolina, August 17-20, 1997 [ed. by Malik, V. S.\Mathre, D. E.]. Ottawa, Canada: North American Plant Protection Organization, 49-60

Liro JI, 1934. Mycotheca Fennica. Die Etiketten Nos. 1-300. Helsingfors, Finland: Institute für Phytopathologie, University Helsinkiensis

Loughman R, 1989. Chemical control in Western Australia of soilborne flag smut caused by Urocystis agropyri. Australasian Plant Pathology, 18:94-95

Mamluk OF, 1998. Bunts and smuts of wheat in North Africa and the Near East. Euphytica, 100:45-50

Mathur SB, Kongsdal O, 2003. Common laboratory seed health testing methods for detecting fungi. Bassendorf, Switzerland: International Seed Testing Association, 425 pp

McAlpine D, 1910. The smuts of Australia, their structure, life history, treatment, and classification. Melbourne, Australia: Department of Agriculture of Victoria, 288 pp

McBeath JH, Cheng M, Gay PA, Yokogi T, 2008. First report of leaf smut on fescue (Festuca rubra) caused by Urocystis agropyri in interior Alaska. Plant Disease, 92(4):652. HTTP://www.apsnet.org

Meiners JP, Fischer GW, 1957. Some new grass smut records from the western states. III. Mycologia, 49:767-771

Metcalfe PB, Brown JF, 1969. Evaluation of nine fungicides in controlling flag smut of wheat. Plant Disease Reporter, 53:631-633

Mordue JEM, Waller JM, 1981. CMI Descriptions of Pathogenic Fungi and Bacteria, No. 716. Wallingford, UK: CAB International

Murray GM, Brown JF, 1987. The incidence and relative importance of wheat diseases in Australia. Australasian Plant Pathology, 16(2):34-37; 11 ref

NCBI, 2009. Entrez cross-database search engine. Maryland, USA: National Center for Biotechnology Information. http://www.ncbi.nlm.nih.gov/sites/gquery

Neergaard P, 1977. Seed Pathology. Volume 1. London, UK: Macmillan Press Ltd., 839 pp

Nelson BD Jr, Duran R, 1984. Cytology and morphological development of basidia, dikaryons and infective structures of Urocystis agropyri from wheat. Phytopathology, 74(3):299-304

Nus JL, Hodges CF, 1990. Tiller and rhizome growth of water-stressed Poa pratensis 'Merion' infected by Ustilago striiformis or Urocystis agropyri. Plant Disease, 74(11):886-888

Platz GJ, Rees RG, 1980. Flag smut resistance in selected wheat cultivars and lines. Queensland Journal of Agricultural and Animal Sciences, 37(2):141-143

Purdy LH, 1965. Flag smut of wheat. Botanical Reviews, 31:565-606

Purdy LH, Allan RE, 1967. Heritability of flag smut resistance in three wheat crosses. Phytopathology, 57:324-325

Purdy LH, Holton CS, 1963. Flag smut of wheat, its distribution and coexistence with stripe rust in the Pacific Northwest. Plant Disease Reporter, 47:516-518

Rees RG, Platz GJ, 1973. Grass host for wheat flag smut. Australian Plant Pathology Society Newsletter, 2(4):28

Rewal HS, Goel RK, Jhooty JS, 1986. Seed and soil inoculation in relation to the incidence of flag smut in wheat. Indian Phytopathology, 39(4):599-600

Richardson MJ, 1990. An annotated list of seed-borne diseases. Zurich, Switzerland: The International Seed-Testing Association

Roane CW, Roane MK, 1996. Graminicolous fungi of Virginia: fungi associated with genera Aegilops to Digitaria. Virginia Journal of Science, 47:197-224

Rossman AY, Britton K, Luster D, Palm M, Royer MH, Sherald J, 2006. Evaluating the threat posed by fungi on the APHIS List of Regulated Plant Pests. Plant Health Progress, May:1-3. http://www.plantmanagementnetwork.org/php/

Sampson K, 1940. List of British Ustilaginales. Transactions of the British Mycological Society, 24(3-4):294-311 pp

Sampson MG, Watson AK, 1985. Host specificity of Urocystis agropyri isolated from Agropyron repens. Canadian Journal of Plant Pathology, 7(1):52-54

Sansford CE, Beales PA, Clarkson JDS, 1998. First report of flag smut of wheat caused by Urocystis agropyri in the United Kingdom. Plant Disease, 82(12):1403

Sansford CE, Beales PA, Clarkson JDS, 1999. Erratum: first report of flag smut of wheat caused by Urocystis agropyri in the United Kingdom (Plant Disease (1998) 82(12):1403). Plant Disease, 83:400

Savile DBO, 1953. Notes on boreal Ustilaginales. Canadian Journal of Botany, 31:663-674

Sharma BK, Satyavir, Beniwal MS, Yadava RK, 2005. Pathogenic variability and differential response of Urocystis agropyri collections on Triticum sp. Environment and Ecology, 23(Special 2):276-280

Shekhawat PS, Shekhawat PS, Majumdar VL, 2011. Relative efficacy of different seed dressing fungicides against flag smut of wheat. Indian Phytopathology, 64(3):303-304. http://www.ipsdis.org

Singh HB, Sethi GS, 1975. Reactions of wheats to flag smut. Indian Journal of Genetics and Plant Breeding, 35(3):450-453

Smiley RW, Dernoeden PH, Clarke BB, 2005. Compendium of turfgrass diseases. Third edition. St. Paul, Minnesota, USA: American Phytopathological Society, 167 pp

Takahashi K, Iwata Y, 1964. The mode of infection of flag smut fungus on wheat varieties differing in resistance. Annals of Phytopathological Society of Japan, 29:149-154

Tariq AH, Khan SH, Saleem A, 1992. Control of flag smut (Urocystis agropyri) through screening of varieties and systemic seed-dressing fungicides. Pakistan Journal of Phytopathology, 4(1-2):32-36

Thirumalachar MJ, Dickson JG, 1949. Chlamydospore germination, nuclear life cycle and artificial culture of Urocystis agropyri on Red Top. Phytopathology, 39:333-339

UK CAB International, 1991. Urocystis agropyri. [Distribution map]. Distribution Maps of Plant Diseases, April (Edition 5). Wallingford, UK: CAB International, Map 80

USDA/SMML, 2005. Nomenclature fact sheets. Urocystis agropyri. Nomenclature fact sheets. Urocystis agropyri. Beltsville, Maryland, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service. USDA, unpaginated. http://nt.ars-grin.gov/sbmlweb/fungi/nomensheets.cfm

USDA-ARS, 2009. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Vánky K, 1994. European smut fungi. Stuttgart, Germany; Gustav Fischer Verlag, 570 pp

Vánky K, 2007. Smut fungi of the Indian Subcontinent. Polish Botanical Studies, 26:265 pp. http://www.ib-pan.krakow.pl/ibwyd/pbs/pbs.htm

Vánky K, Shivas RG, 2008. Fungi of Australia: the smut fungi [ed. by Vánky, K.\Shivas, R. G.]. Canberra, Australia: Australian Biological Resources Study, viii + 267 pp

Wattspadwick G, 1948. Plant protection and food crops of India I. Plant pests and diseases of rice, wheat, sorghum and gram. Empire Journal of Experimental Agriculture, 16:55-64

Wiese MV, 1987. Compendium of wheat diseases. Second edition. St. Paul, Minnesota, USA: American Phytopathological Society, 112 pp

Wolff R, 1873. Beitrag zur Kenntnis der ustilagineen. Botanische Zeitschrift, 31:657-661

Yasu M, Yoshino M, 1963. Studies on the ecology of the flag smut of wheat and its control. Saitama Agricultural Experiment Station, Japan Research Bulletin, 20:1-34

Zundel GL, 1953. The Ustilaginales of the World. Pennsylvania State College, School of Agriculture, Contribution No. 176. Pennsylvania, USA: Pennsylvania State College

Distribution References

Bansandrai A K, Sood A K, Sud A K, 1993. Prevalence of flag smut of wheat (Urocystis agropyri) in Himachal Pradesh. Plant Disease Research. 8 (1), 85.

Bhatnagar G C, Gupta R B L, Mishra V L, 1978. Effect of flag smut, caused by Urocystis agropyri on yield components of wheat cultivars in Rajasthan, India. Plant Disease Reporter. 62 (4), 348-350.

BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens., Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. http://www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm

CABI, Undated. Compendium record. Wallingford, UK: CABI

CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Denchev C M, 2001. Fungi Bulgaricae, Vol. 4. Class Ustomycetes (Orders Tilletiales, Ustilaginales, and Graphiolales). 350 pp.

El-Buni A M, Rattan S S, 1981. Check list of Libyan fungi. Tripoli, Libya: Al Faateh University Faculty of Science, Department of Botany. 169 pp.

EPPO, 2014. EPPO Global database (available online). Paris, France: EPPO. https://gd.eppo.int/

EPPO, 2020. EPPO Global database. In: EPPO Global database, Paris, France: EPPO.

Guo L, 2005. Ustilaginales. In: Fungi of Northwestern China. [ed. by Zhuang W Y]. Ithaca, New York, USA: Mycotaxon, Ltd. 291-304.

McBeath J H, Cheng M, Gay P A, Yokogi T, 2008. First report of leaf smut on fescue (Festuca rubra) caused by Urocystis agropyri in interior Alaska. Plant Disease. 92 (4), 652. HTTP://www.apsnet.org DOI:10.1094/PDIS-92-4-0652A

Meiners J P, Fischer G W, 1957. Some new grass smut records from the western states. III. Mycologia. 767-771.

Murray G M, Brown J F, 1987. The incidence and relative importance of wheat diseases in Australia. Australasian Plant Pathology. 16 (2), 34-37. DOI:10.1071/APP9870034

Roane C W, Roane M K, 1996. Graminicolous fungi of Virginia: fungi associated with genera Aegilops to Digitaria. Virginia Journal of Science. 197-224.

Sansford C E, Beales P A, Clarkson J D S, 1998. First report of flag smut of wheat caused by Urocystis agropyri in the United Kingdom. Plant Disease. 82 (12), 1403. DOI:10.1094/PDIS.1998.82.12.1403D

SENASA, 2020. NPPO communication to CABI., Buenos Aires, Argentina: SENASA.

Sharma B K, Satyavir, Beniwal M S, Yadava R K, 2005. Pathogenic variability and differential response of Urocystis agropyri collections on Triticum sp. Environment and Ecology. 23 (Special 2), 276-280.

UK, CAB International, 1991. Urocystis agropyri. [Distribution map]. In: Distribution Maps of Plant Diseases, Wallingford, UK: CAB International. Map 80.

Zundel G L, 1953. The Ustilaginales of the world. Pennsylvania, USA: Pennsylvania State College.

Contributors

10/09/09 Updated by:

Distribution Maps