Reaction of Eyespot Causal Agents to some Active Ingredients of Fungicides In Vitro
Winter wheat samples infected by eyespot were collected during the years 2015–2017. In total 143 Oculimacula spp. isolates were obtained and determined by PCR. Oculimacula yallundae isolates prevailed (122) over Oculimacula acuformis isolates (12) and 9 mixed isolates of both species. O. acuformis predominated only on one locality. The reaction of 104 Oculimacula spp. isolates to ten different fungicides was evaluated in laboratory tests on Petri dishes. The highest efficacy showed the combination of epoxiconazole + fluxapyroxad + pyraclostrobin and the lowest efficacy was evaluated after application of prothioconazole + trifloxystrobin. The decrease of efficacy of fungicide no. 6 (prothioconazole + trifloxystrobin) has been observed since 2015. The sensitivity of 114 Oculimacula spp. isolates to prochloraz has been tested. More than half of the isolates (58%) showed low to medium resistance. One isolate of O. yallundae from the year 2017 showed high resistance to prochloraz (ED50 ranged 1.7 µg ∙ ml–1). The rest of the isolates (42%) were sensitive to prochloraz.
KeywordsOculimacula yallundae Oculimacula acuformis wheat fungicide resistance prochloraz
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