Sensitivity of the causative agent of net blotch of barley (Pyrenophora teres Drechsler) to fungicides

Abstract

The research was carried to study the effect of fungicides of various classes on the intrapopulation structure of Pyrenophora teres in terms of sensitivity to toxicants, virulence and racial composition. The work was performed using eight treatment options in different doses (control without fungicide, 25 %, 50 %, 75 %, 100 % (the norm), 125 %, 150 %, 175 %, 200 %) fungicides 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), Orgamika C, L (0.4 l/ha) of plants and introduction to a nutrient medium with a pure culture of P. teres. The racial composition of the populations was determined using an international set of differentiator varieties. When treating plants with fungicides with the norm allowed for use in agriculture, the minimum efficiency values were found in the preparations Quadris, SC (52.3 %), Orgamika C, L (66.8 %), the maximum - Magnello, EC (88.2 %) and Kolosal Pro, MC (97.0 %). The average virulence of the population isolated after Quadris, SC treatment was revealed to be maximum - 3.4 points (at the control level). The greatest racial diversity was found in P. teres populations isolated after treatment with fungicides based on triazoles Magnello, EC (CF=0.10) and strobilurines Quadris, SC (CF=0.10). The maximum intrapopulation heterogeneity was revealed 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). When introducing the permitted rate of drugs into the pure culture of P. teres, on average, the growth of colonies slowed down from 86.1 % (Quadris, SC) to 100 % (Amistar Trio, EC). Preparations based on strobilurines and Bacillus amyloliquefaciens completely prevented sporulation. The results obtained allow us to conclude that there is a shift in sensitivity to the studied drugs.