Crown rust (barley)
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It has been suggested that this article or section be merged with Puccinia coronata. (Discuss) |
Crown rust is a fungal disease of barley caused by Puccinia coronata var. hordei. It is a relatively new disease of barley in North America. It was first found in 1992 in a barley breeding nursery near Clay Center, Nebraska.[1] Since then, crown rust has been found throughout the upper Midwest, with greatest incidence in the central Red River Valley of North Dakota and Minnesota. In that region the alternate host, common buckthorn (Rhamnus cathartica), grows abundantly in shelter belts and riparian areas. Since 1993, outbreaks of crown rust have occurred on barley and forage grasses at several localities in this region. The extent of yield losses in barley caused by this disease have not been determined. Crown rust poses a threat to barley production, because the first infections in barley occur early in the season from local inoculum.[2]
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[edit] Symptoms
Uredinia are linear, light orange, and occur mostly on the leaf blades but occasionally occur also on leaf sheaths, peduncles and awns. Extensive chlorosis is often associated with the uredinia. Telia are mostly linear, black to dark brown, and are covered by the host epidermis.[2]
[edit] Disease cycle
Teliospores on barley straw and residue of susceptible grasses left in the field germinate in the spring and produce basidiospores that infect R. cathartica. Pycnial and aecial stages are produced on the alternate host. Aeciospores from R. cathartica are the primary inoculum for infecting barley. The primary infections, which can occur as early as the three leaf stage of barley in the spring, develop into uredinia. Urediniospores produced in the uredinia repeat the infection process, and the fungus undergoes several cycles of reproduction on barley during the growing season. Spread by wind-borne urediniospores can carry the fungus some distance from the R. cathartica bushes that were the original sources of primary inoculum, although such secondary spread seems much less extensive than that for oat crown rust. [2]
Barley crown rust can infect rye as well as barley. In addition, it also infects a number of grasses in nature including quackgrass (Elytrigia repens), slender wheatgrass (Elymus tranchycaulus), western wheatgrass (Pascopyrum smithii), foxtail barley (Hordeum jubatum), and several wheatgrasses (Elytrigia spp.) and wild rye grasses (Elymus spp. and Leymus spp.). The fungus readily forms telia on these hosts, which serve as a reservoir of overwintering teliospores. Quackgrass may be the most important reservoir for overwintering telia. This ubiquitous, perennial weed is very susceptible to the rust and is often found growing near Rhamnus.
[edit] Management
Sources of resistance to crown rust have been identified in barley germplasm from diverse regions, but most malting barley cultivars currently grown in the northern Great Plains of North America are susceptible to crown rust. [2]
[edit] External links
Jin, Y.; B.J. Steffenson (1993). "Natural occurrence of barley crown rust on forage grasses in North Dakota and its pathogenicity on gramineous species (Abstr)". Phytopathology 83: 884.
Jin, Y.; B.J. Steffenson, J.D. Franckowiak (1993). "Resistance to crown rust in barley and its inheritance in CI 1243 (Abstr)". Phytopathology 83: 1336.
Jin, Y.; B.J. Steffenson, D.M. Wesenberg, H.E. Bockelman (1993). "Reaction of Triticum species and related genera to barley crown rust (Abstr)". Phytopathology 83: 1387.
Jin, Y.; B.J. Steffenson (2002). "Sources and genetics of crown rust resistance in barley". Phytopathology 92: 1064–1067. doi:.
[edit] References
- ^ Jin, Y.; B.J. Steffenson, L.E. Oberthur, P.S. Baenziger (1992). "Puccinia coronata on barley (Disease Notes)". Plant Dis. 76: 1283.
- ^ a b c d USDA ARS
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