Virulence of Icelandic Pyrenophora teres f. teres populations and resistance of Icelandic spring barley lines

The causal agent of the barley net blotch disease, Pyrenophora teres, is known for its high level of diversity due to sexual reproduction. Different pathotypes, defined by a virulence combination, even within the same fields are frequently found and virulence between locations can vary considerably. Evaluation of virulence patterns of a pathogen population is essential for breeding resistant cultivars suitable for specific locations. To identify virulence patterns in Icelandic Pyrenophora teres f. teres (Ptt) isolates, twenty single spore isolates of Ptt were collected from seven locations in Iceland and analysed with AFLP markers. Principle Coordinate Analysis (PCoA) revealed Icelandic Ptt isolates clustering away from reference isolates from Austria, Finland, Sweden, Switzerland, UK, and USA. Hierarchical clustering grouped the Icelandic isolates into three distinct groups. Furthermore, the virulence of these twenty isolates was tested on 16 barley differential lines and revealed high variation in their virulence. Twenty-one barley cultivars commonly used in Iceland showed high susceptibility towards inoculation with Icelandic Ptt isolates.

Phytosanitary condition of winter barley crops in the Krasnodar krai and the Republic of Adygea in the pre-harvest period

Phytosanitary monitoring is the most important element of integrated plant protection. It is used to identify the state of crops, the spread of diseases, the degree of their damage, and also to plan the protective measures. The aim of the research was to assess the development of the most dangerous diseases on winter barley crops in the Krasnodar Krai and the Republic of Adygea (alternate spelling: Adygeya) in the pre-harvest period in 2017–2019 (late May-beginning of June, late milk-early dough stage of development (Z 70-75)). The analysis of the three-year dynamics of pathogens development on winter barley was carried out. The obtained data were compared with the agro-climatic conditions of the growing seasons. Phytosanitary and agroecological observations were carried out according to generally accepted methods and techniques. In the agricultural season 2016–2017, the weather in autumn was warm; winter was mild and snowless; spring was early with an unstable temperature regime and significant lack of precipitation. Warm and dry autumn, snowless winter with long thaws, spring with temperature changes were observed during the growing season of 2017–2018. Autumn in the 2018–2019 vegetative season was cool. Winter was mild and snowless. Sharp changes in air temperature were observed in spring. There was a shortage of precipitation, however, heavy precipitation was noted later. Spot blotch of barley (Cochliobolus sativus (S. Ito & Kuribayashi) Drechs.), barley net blotch (Pyrenophora teres Drechsler.), powdery mildew of barley (Blumeria graminis (DC.) Speer) and leaf rust of barley (Puccinia hordei G. H. Otth.) were detected in the pathogenic complex of the crop. Different types of leaf spots of barley dominated among the detected plant diseases. Intensive development of spot blotch was observed on winter barley crops in Kurganinsky (47.9 %), Dinsky (30.0 %), Novokubansky (28.3 %) and Vyselkovsky (26.3 %) districts, as well as in the Maykop district of the Republic of Adygea (28.3 %). Significant development of barley net blotch was recorded in Kushchevsky (33.5 %), Dinsky (30.8 %) and Novokubansky (29.2 %) districts. The level of powdery mildew development was low (up to 1 %) in all regions. Just a few cases of leaf rust of barley during three years of research were noted. The results of phytosanitary monitoring are presented in the form of electronic maps of the spread of winter barley diseases in the regions of the Krasnodar Krai and the Republic of Adygea.

Study of the influence of barley varieties with different resistance to barley net blotch on the change in the structure of the hemibiotrophic pathogen population by morphological and cultural characteristics and virulence

The study is devoted to the analysis of the correlation of morphological and cultural characteristics and virulence of Pyrenophora teres Drechs. isolates, and various resistance to the pathogen of barley varieties (Versal, Kubagro-1, Romance). The main morphological types of colonies of the fungus isolates obtained from the barley varieties with different resistance were determined. It was found that the higher degree of resistance of the variety, the faster growth rate of colonies, the intensity of sporulation and heterogeneity of the population on the basis of virulence increase. The most common races were detected in the populations of P. teres isolated from different varieties of barley. We found that the selection for the virulence of the pathogen population in Versal variety with a high level of non-specific resistance was carried out with a wider spectrum of diversity.

Management of barley net blotch using Trichoderma asperellum (T34), eugenol, non-traditional compounds and fungicides

Barley plants (cv. Giza 2000) are infected by Drechslera teres which causes net blotch disease symptoms and yield losses. Plants were treated with commercial molecular products such as Trichoderma asperilium (T34), eugenol compared to non-traditional compounds (potassium silicate, nano-selenium) and fungicides (Maven, Montoro, and Decent) which selected from 12 treatments according to their important effects on infected barley plants. Bio-arc, Tilt, Rush up, Curve, and Amisto treatments were left out because of their lower efficiency of some treatments and similarity of the active ingredients of some other of them.Disease severity (%) was significantlty decreased as a result of the selected treatments, except eugenol which showed less reduction than the control. Disease symptoms were suppressed and electrolyte leakage % was reduced significantly due to all treatments than the control treatment. As a consequence of treatments, endogenous reactive oxygen species (ROS) such as superoxide (O2−) was significantly elevated early after the inoculation, consequently, later on catalase (CAT), peroxidase (POX), and polyphenol oxidase (PPO) activities were increased significantly than the control. Elevated levels of O2− early after inoculation could play essential role in killing or suppressing the fungus and inhibiting disease symptoms as well as stimulated enzyme activities. Interestingly, the treatments were effective so that the yield characters (1000 K.W. and grain yield/plo) were increased significantly than the control treatment. These results indicated that the biological commercial product of Trichoderma asperilium 34 and non-traditional biological compounds in this research study are so effective and could be used as an alternative to fungicides.

IMMUNOLOGICAL ASSESSMENT OF THE HULLED BARLEY COLLECTION ACCORDING TO ITS RESISTANCE TO LEAF DISEASES IN THE SOUTHERN PART OF THE ROSTOV REGION

In the conditions of artificial infectious background of the laboratory of plant immunity and protection (Agricultural Research Center “Donskoy”) there has been conducted an immunologic estimation of hulled barley samples of ARIR collection. There has been estimated resistance to the following pathogens: powdery mildew (pathogen Erysiphegraminis f. hordei), barley net blotch (Pyrenophorateres (Died.) Drechsler [Drechslerateres (Sacc.) Shoemaker]) and barley dark-brown blotch (Bipolaris sorokiniana (Sacc.), Shoemaker [Cochliobolussativus (S. Ito &Kurib) Drechsler ex Dastur, Helminthosporiumsativum Pammel, C.M. King & Bakke]). The study of disease manifestation was done in 2016–2017. The results allow estimating variety resistance in the extreme infectious conditions similar to epiphytotinous conditions. As a result there have been identified the samples ‘Dublet’ (Belorussia), ‘Omsky golozerny 1’ (Russia), ‘К-26648’ (Pakistan), ‘Back CDC’,’CDC VC Ywire’, ‘CDC Dawn’ (Canada), ‘К-3038’ (Dai Mai), ‘Orgeniepetite’ (France), ‘NB-OWA’ (Nepal) and others that showed resistance and slight susceptibility to powdery mildew. The samples ‘Back CDC’, ‘Bowman’ (Canada), ‘84469/70’, ‘К-303’ (Dai Mai), ‘Dublet’ (Belorussia), Brunее (Ethiopia), ‘Orgeniepetite’ (France) and others showed resistance to barley net blotch. The samples ‘Dublet’, ‘Omsky golozerny 1’, ‘Omsky golozerny 2’, ‘Yudinsky 1’, ‘К-26648’, ‘84469/70’, ‘Orgeniepetite’, ‘CDC Dawn’, ‘NB-OWA’, ‘К-3038’, ‘CDC VC Ywire’, ‘E.E.B.N.46’ demonstrated a complex resistance to both pathogens and they are recommended for use in the breeding programs on immunity.