| Uromyces viciae-fabae var. viciae-fabae | |
|---|---|
| Scientific classification | |
| Kingdom: | Fungi |
| Phylum: | Basidiomycota |
| Class: | Urediniomycetes |
| Subclass: | Incertae sedis |
| Order: | Uredinales |
| Family: | Pucciniaceae |
| Genus: | Uromyces |
| Species: | U. viciae-fabae var. viciae-fabae |
| Binomial name | |
| Uromyces viciae-fabae var. viciae-fabae (Pers.) J. Schröt., (1875) |
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| Synonyms | |
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Capitularia fabae (Pers.) Syd., (1922) |
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Uromyces viciae-fabae var. viciae-fabae is a plant pathogen commonly known as Faba-bean rust. It is a leaf and stem rust of beans and causes partial defoliation, a reduction in photosynthetic leaf surface and a reduction in yield.[1]
This rust fungus occurs on both cultivated and wild plants of Vicia, Lathyrus, Pisum and Lens.[2] It is autoecious, completing its life cycle on one plant host and macrocyclic, producing five types of spores during its life cycle.[3]
Contents |
The spermogonia are mostly on abaxial leaf surfaces.
The aecia are mostly on abaxial surfaces in small groups, mostly near the veins, the peridium is cupulate and whitish with spores 18–26 by 15–21 µm, broadly ellipsoid and verrucose.
The uredinia are amphigenous and yellowish-brown with spores 24–29 by 19–22 µm, broadly ellipsoid, pale golden and uniformly echinulate, normally with four pores, either equatorial or variously distributed and with small caps.
The telia are sometimes on the adaxial surfaces or sometimes amphigenous and on stems, exposed, blackish brown and compact with spores 27–35 by 19–23 µm, oval or obovoid, smooth and chestnut brown, the pedicels brownish and about 60 µm long.[4]
The telia survive in a semi-dormant state in crop residues both in the field and on seed. The teliospores they produce are blown by the wind and come to rest on volunteer plants and seedlings, infecting them. Aecia are produced and liberate aeciospores which spread the infection within the crop and to other nearby bean crops. Uridinia are produced on the stems and leaves and liberate urdiniospores which spread the rust throughout the crop canopy. Late in the season, telia form on stems and leaves and remain in crop debris after harvest ready to infect next season's crop.[5]
When faba-bean rust is present, leaves of infected plants exhibit many small, orange-brown pustules, each surrounded by a pale yellow halo. Severely infected leaves wither and may drop from the plant. Larger pustules occur on the stems and isolated pustules may be found on the pods. Severe infection may result in reduced seed size and may cause yield losses of up to 30%, while in combination with chocolate spot, yield reductions of over 50% have occurred.[5] Control measures include the use of resistant varieties of bean and the strategic use of foliar fungicides, which need to be applied before heavy infections occur to minimise crop losses.[5]