Diseases

Puccinia dispersa Erikss. et Henning (Puccinia recondita Rob.ex Desm. f. sp. secalis), - Brown (leaf) rust of rye.

Systematic position.

Class Basidiomycetes, subclass Teliosporomycetidae, order Uredinales, family Pucciniaceae, genus Puccinia.

Biological group.

Biotroph.

Morphology and biology.

Puccinia dispersa is a heteroecious, macrocyclic, obligate parasitic fungus. Stages 0-I develop on Anchusa spp. and Lycopsis spp., II-III on species of Secale and others Poaceae. The disease symptoms are very similar to those in Brown Rust of Wheat. Brown Rust of Rye is present as round or oval red-brown pustules with urediniospores on leaves. The pustules may be situated on both surfaces of leaves, sometimes on leaf sheaths. Urediniospores are spheric, oval, with 8-10 pores. The telia are located on the lower side of leaves or on the leaf sheaths, black, covered with epidermis. Teliospores are spheric, clavate. Telia over-winter; in spring the teliospores germinate and produce haploid basidiospores, which infect an alternative host, forming spermogonia. The spermacia copulate, and a new diploid generation forms aecia on the lower side of leaves. The aeciospores infect rye or other Gramineae, forming uredia and starting a new uredinial stage (Ishkova et al., 2002). Teliospores may also germinate and infect an alternative host in autumn, and then the gramineous hosts may be infected with aeciospores in autumn, and the fungus hibernates as uredomycelium within plant leaves. The hibernation by uredomycelium is also common when the winter rye is infected in autumn with urediniospores. Normally, the full life cycle is rare, and the fungus lives and hibernates in urediniostage (Transhel, 1939).

Distribution.

Occurs in different countries of Europe, Asia, America, and Australia with rye cultivation. In Russia it is found in all regions where rye is cultivated (Transhel, 1939; Ishkova et al., 2002).

Ecology.

Urediniospores germinate and penetrate leaves at 1-25.C (optimal temperature is 9-22.C) in the presence of condensed moisture (dew). Under favorable conditions an uredogeneration develops for 6-7 days, so the development of several generations is possible for a season (Nazarova et al., 1988). The urediniospores disseminate by wind for a short or long (hundreds km) distance.

Economic significance.

Leaf rust is a dangerous disease of rye. The infection results in reduced yield, and lowers test weight. Yield losses during epiphytotic conditions amounts to 20-40% (Solodukhina, 1985). Control measures include the use of resistant varieties, seed dressing, and fungicide application (Solodukhina, 1985; Nazarova et al., 1988).

Reference Citations:

Ishkova T.I., Berestetskaya L.I., Gasich E.L., Levitin M.M., Vlasov L.Iu. 2002. Diagnostics of the main fungus diseases of cereal crops. Saint Petersburg: VIZR. 76 p. (In Russian)
Nazarova L.N., Polityko P.M, Fochenkova T.V. 1988. Rye protection against rust in intensive cultivation technology. Moscow: State Agropom. Com. 7 p. (In Russian)
Solodukhina O.V. 1985. Virulence of Brown Rust on sowings of short-stemmed diploid winter rye. Bulletin of Appl. Bot., Genet. And Plant Breeding, 92: 47-51. (In Russian)
Transhel V.G. 1939. Review of rust fungi of the USSR. Moscow-Leningrad: Nauka. 426 p. (In Russian)

© Dmitriev A.P.