Diseases
Uromyces striatus Schrot. - Rust of Alfalfa.
Systematic position.
Division Basidiomycota, order Uredinales, family Pucciniaceae, genus Uromyces.Synonym.
Uromyces oblongus Vize.Biological group.
Biotroph parasite.Morphology and biology.
Aecia and spermogonia are formed on Euphorbia spp., uredinia and telia are formed on Medicago spp. Mycelium of aecial and spermogonial stages penetrates into all plant. Euphorbia plants are yellowish, frequently oppressed and deformed. Spermogonia are scattered among aecia on the lower leaf surface, pear-shaped, submerged, 240 x 180 mkm on the average. Aecia calciform or cuplike, orange, with serrated bent bladed edge of peridium. Aeciospores globose-polygonal, orange, spinose, 15-18 mkm in diameter. Round rust-brown small pads, or uredinia, producing powder are formed at first on the lower leaf surface, and then on their upper surface and on stems of Alfalfa. Urediniospores unicellular, spherical or widely-elliptical, 15-23 x 15-20 mkm; with light-brown coat, rarely spinose, with four pores located along equator. Later round, convex, dark-brown, velvety, small pads, or telia, are formed among uredinia, weakly producing powder. Telia are located mostly on the lower leaf surface and on stems. Teliospores are oval, egg-shaped or round, 15-22 x 15-20 mkm; with dark-brown coat, longitudinal stripes, and with apical papilla to 4 mkm in height. Pedicel short, hyaline. In northern areas the fungus winters as mycelium in Euphorbia spp. roots. In southern areas (in Central Asia especially) it winters as urediniospores. The disease appears at the end of May or in June, developing till late autumn. The greatest disease severity is marked in August - September.Distribution.
Everywhere in areas of Alfalfa cultivation.Ecology.
Temperature 18-22 .C and relative air humidity 40-50% are optimum for the disease development.Economic significance.
The disease results in decrease of hay yield and reduction of its nutritional value. At high severity the decrease of seed productivity by 25% is marked. Protective actions: optimum terms of hay harvesting, i.e., in the beginning of flowering, agronomical measures, cleaning of field margins and irrigation canal banks from wild-growing species of Alfalfa and Euphorbia, resistant cultivars, spraying by fungicides.Related references.
Berdysh, Yu.I. 2004. Distribution of the main pests and diseases of crops in Krasnodar territory in 2003 and the forecast of their occurrence in 2004. Krasnodar: STAZR, p. 35. (in Russian).Borisov, S.Yu., Bystrova, E.V., Khodkevich, L.I., Sidorova, V.F.& Baranova, L.B. 1999. Review of pests and diseases distribution in crops in 1999 and forecast of its occurrence in Saratov Region in 2000 year. Saratov: Region station for plant protection "Saratovskaya", p.14. (in Russian).
Guseva, T.A. & Frolovskaya, V.A., 1971. Diseases of leguminous grasses. In: Polyakov, I.Ya. & Minkevich, I.I., eds. Distribution of pests and diseases of agricultural crops in RSFSR in 1970 and the forecast of their occurrence in 1971. Moscow: VIZR, p. 136-138. (in Russian).
Hawksworth D.L., Kirk P.M., Sutton B.C. & Pegler D.N. 1995. Ainsworth & Bisby's Dictionary of the fungi. 8th edition. Kew, Surrey: Commonwealth Mycological Institute, 616 p.
Kalinina, I.G., Krivko, V.I., Parshikov, A.T., Anyutina, L.R., Shirokov, A.I. & Ionin, P.F. 1985. Forecast of pests, diseases and weeds distribution in crops in Omsk Region for 1985 and its control. Omsk: Omsk book publishing house, p. 20. (in Russian).
Karimov, M.A.1961. Fungal parasites of Alfalfa. Tashkent: Ministry of agriculture of Uzbekistan, 208 p. (in Russian).
Luk.yanova, L.G., Nikiforova, L.S., Komarova, L.V., Kulakova, M.A., Chechenina, M.S., Bakulina, G.F., Emel.yanova, G.A., Bandulevich, N.I., Razumova, M.N., Dmitrieva, S.N., Gordenko, V.I., Mukhina, M.Yu. & Phephelova, N.N. 2001. Forecast of the pests and diseases occurrence and distribution in crops in 2001 year and its control. Nizhnii Novgorod: Nizhegorodskaya region station for plant protection, p. 11. (in Russian).
Pokataev, V.A., Romanov, G.I., Pokhvalenko, L.E., Golovko, S.F., Tyurganova, A.E., Romanova, A.K. & Fedorovskii, L.D. 1975. Forecast of pests and diseases occurrence in crops in 1975 year and its control in Stavropol Territory. Stavropol: Stavropol Territory station for plant protection, p.62. (in Russian).