Sensitivity of the Causative Agent of Net Blotch of Barley (Pyrenophora teres Drechsler) to Fungicides

• Published in: Russian agricultural sciences Vol. 50; no. 1; pp. 40 - 45
• Main Authors: Volkova, G. V., Yakhnik, Ya. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2024; Springer Nature B.V
• Subjects: Agriculture; Bacillus amyloliquefaciens; Barley; Biomedical and Life Sciences; Biotechnology; Composition; Crop Production; Fungicides; Heterogeneity; Life Sciences; Net blotch; Pesticides; Plant Biochemistry; Plant Protection; Populations; Pure culture; Pyrenophora teres; Sensitivity; Sensitivity analysis; Sporulation; Toxicants; Triazoles; Virulence; fungicides; winter barley; resistance; net blotch of barley leaves
• ISSN: 1068-3674; 1934-8037
• DOI: 10.3103/S1068367424010166

This research was carried to study the effect of fungicides of various classes on the intrapopulation structure of Pyrenophora teres in terms of its sensitivity to toxicants, virulence, and racial composition. The study involved eight variants of winter barley treatment with Magnello, EC (1 L/ha), Capella, M (1 L/ha), Kolosal Pro, MC (0.4 L/ha), Quadris, SC (1.2 L/ha), Amistar Trio, EC (1 L/ha), and Orgamika C, L (0.4 L/ha), which were introduced to the nutrient medium with a pure culture of P. teres at doses of 25, 50, 75, 100, 125, 150, 175, and 200% of the norm (control without treatment). The racial composition of the populations was determined using an international set of differentiator varieties. When treating plants with fungicides at the rates permitted for agricultural use, the minimum levels of efficiency were recorded for Quadris, SC (52.3%) and Orgamika C, L (66.8%) and maximum levels of efficiency for Magnello, EC (88.2%) and Kolosal Pro, MC (97.0%). The average virulence of the population isolated after Quadris, SC treatment proved to be maximum: 3.4 points (at the control level). The greatest racial diversity has been found in P. teres populations isolated after treatment with fungicides based on Magnello, EC triazoles (CF = 0.10) and Quadris, SC strobilurins (CF = 0.10). The maximum intrapopulation heterogeneity has been recorded in populations isolated after treatment with fungicides based on triazoles and Bacillus amyloliquefaciens: Kolosal Pro, MC (Sh = 2.16), Capella, M (Sh = 2.14), Magnello, EC (Sh = 2.10)), and Orgamika C, L (Sh = 2.12). After introducing the permitted rate of fungicides into the pure culture of P. teres, the average growth rate of the colonies slowed down from 86.1% (Quadris, SC) to 100% (Amistar Trio, EC). Fungicides based on strobilurins and Bacillus amyloliquefaciens completely prevented sporulation. The results of the research suggest that there is a shift in sensitivity to the test drugs.