Diseases
Pyrenophora graminea Ito & Kuribayashi [anamorph Drechslera graminea (Rabenh.) Shoemaker] - Barley Stripe
Systematic position.
Anamorth: class Hyphomycetes, order Hyphomycetales, family Dematiaceae, genus Drechslera. Teleomorph: slass Loculoascomycetes, subclass Loculoascomycetidae, order Dothidealis, family Pleosporacea, genus Pyrenophora.Synonym.
Helminthosporium gramineum Rabenh.Biological group.
Hemibiotrophic parasite, attacking cultivated barley.Morphology and biology.
First symptoms appear on the second or third leaf of seedlings and on all leaves produced thereafter. Newly developed leaves have yellow stripes, particularly on the leaf sheath and on the basal portion of leaf blade. The stripes gradually extend along the full leaf length and soon become necrotic. Infected plants are usually stunted. Flag leaves are often light tan at the time of heading. In many infected plants, spikes are undeveloped or strongly shriveled, being often brown, but sometimes grain may develop almost normally and exhibit little or no brown discoloration. The variation in symptoms is related to pathogen virulence, host resistance, and the environment. Conidia of D. graminea are borne laterally and terminally on conidiophores, which usually occur in clusters of three to five. The conidia cylindrical and straight, subhyaline to yellow-brown, and having to seven transverse septae (12-23 x 27-110 mkm). Germination can occur from all conidial cells. Pseudothecia are elongated (576-728 x 442-572 mkm), having rigid setae on their surface. Asci 200-425 x 28-45 mkm) are club-shaped, rounded at the apex. Ascospores (45-78 x 20-33 mkm) are light brown and ellipsoidal, with 3 transverse and one longitudinal septae. P. graminea produces also pycnidia in host tissue and in culture. Pycnidia are globose to pear-shaped, 70-176 mkm in diameter, yellow to brown. Pycnidiospores (1.4-3.2 x 1.0-1.6 mkm) are hyaline, nonseptate and spherical. The function of the pycnidial stage is not known. P. graminea survives exclusively as seed born mycelium in hull, pericarp, and seed coat. Embryo is not infected. At the time of heading, conidia are produced on infected leaves under conditions of high moisture. Conidia are spread by wind to nearby heads. Seed can become infected at all stages of development. The most severe infection occurs during the early stages of kernel development. Infection of developing seedlings by seedborne inoculum is greatly influenced on soil temperature and moisture during germination and emergence. The critical stage for infection of the germinating embryo begins when coleoptile reaches the seed apex and continues until the seedling emerges from the soil. Systemic distribution of mycelium continues as the plant elongates and heads. Conidium production on infected leaves is synchronized with heading and early stages of kernel development.Distribution.
Disease is widely distributed throughout the world. In countries of the former USSR it meets everywhere in areas of barley cultivation.Ecology.
Sporulation occurs on infected leaves under conditions of high moisture. About 16 hr is required for conidia to mature at 12.C. Free water is not necessary for infection, which can occur at temperatures between 10 and 33.C. Incubation period is 6-9 days at temperatures from 18 to 22C. and humidity 70-85%. The maximum number of seedlings become infected when soil temperatures are below 12.C. Infection is reduced or prevented at temperatures above 15.C. More infection occurs when the relative humidity is near 100%, at temperatures from 15 to 25.C, with an optimum at about 22.C. Infection of barley leaves is greatest when humid conditions persist for 10-30 hr or longer.Economic significance.
There is only one report of barley stripe harmfulness on the territory of Russian Federation, i.e., in the Kirov Region. Maximal yield losses on the susceptible cultivars reached 31.9%-40.5%. In the scientific literature prior to 1968, and sometimes later, erroneous definition of the Barley Stripe often took place. For example, the items of information on 70-100% of disease severity are given in the book "Distribution of pests and diseases of agricultural cultures in the USSR in 1962 and forecast of their appearance in 1963", though the described symptoms as a local lesions on leaves correspond to the Barley Net Blotch. The harmfulness expressed in yield decrease by 34-36% is marked for Ukraine, by 13.2-22.2% for Georgia. High disease severity to 68% without the indication of losses on irrigable barley fields was recorded in Uzbekistan and South Kazakhstan.Related references:
Baigulova G.K., Aripov U.A., Kislyuk A.E., Pyatonya A.A. 1976. Helminthosporium diseases on the irrigable barley fields. In: Editor. Proceedings of Research Institute of Biological Plant Protection "Some Problems of Agrotechnics of Cereal and Fabaceous Cultures in Uzbekistan". Vol. 12, City: Publisher, p. 141.150 (in Russian).Dorozhkin N.A., Voitova L.R. 1962. To the problem of biology of the causal agent of barley stripe (Helminthosporium gramineum Rabenh.) in Byelorussia. Reports of Academy of Science of BSSR 6: 401.403(in Russian).
Efremova Z.G. 1981. Substantiation of measures on protection against barley stripe in North-East of Non-Chernozem zone of RSFSR. Abstract of PhD Thesis. Leningrad: Publisher, 20p. (in Russian).
Gornostai V.I. 1970. Drechslera Ito on Grasses in Primorskii Territory. Mikologiya i fitopatologiya 4(1): 69.73 (in Russian).
Grachev A.F. 1964. Barley resistance to stripe in conditions of Primorskii Territory. In: Editor. Proceedings of All-Union Institute of Plant Industry. Vol. 1. Leningrad: Kolos, p. 82-85 (in Russian).
Ishkova, T.I., Berestetskaya, L.I., Gasich, E.L., Levitin, M.M., & Vlasov, D.Yu. 2000. Diagnostic of the main diseases of cereals. Saint Petersburg: VIZR, 76 p. (in Russian).
Kononova G.A. 1968. Barley stripe. In: Polyakov I.Ya., Chumakov A.E., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1967 and the forecast of their appearance in 1968. Moscow: Rosselkhozizdat, p. 72 (in Russian).
Mathre D.E., ed. 1997. Compendium of barley diseases. APS PRESS, 90 p.
Natsvlishvili A.A. 1954. Barley stripe (Helminthosporium gramineum Rabenh.) and measures of its control. Abstract of PhD Thesis. Tbilisi: Publisher, 16 p. (in Russian).
Polivani A.M. 1989. Helminthosporium barley leaves blights in North-East Forest-steppe of Ukrainian SSR. - Abstract of PhD Thesis. Leningrad: Publisher, 19 p. (in Russian).
Randalu I. 1959. Distribution and harmfulness of Helminthosporium diseases of barley in Estonian SSR and their control. In: Editor. Reports of Scientific conference on plant protection - Vilnus: Publisher, p. 273-279 (in Russian).
Shchekochikhina R.I. 1963. Barley stripe. In: Editor. Distribution of pests and diseases of agricultural cultures in the USSR in 1962 and forecast of their appearance in 1963. Leningrad: : VASKNIL, VIZR, p. 164-165 (in Russian).
Tyulina L.R. 1975. Helminthosporium diseases of barley in Kirov Region and role of infected seeds in distribution of diseases. In: Editor. Ways of improving cultivation of the main agricultural cultures in Kirov Region. Perm: Publisher, p. 92-99 (in Russian).
Voitova L.R. 1963. Barley stripe. Plant Protection 6: 26-27 (in Russian).