02262naa a2200301 a 450000100080000000500110000800800410001902200140006002400520007410000190012624501240014526000090026950000330027852014200031165000180173165000150174965000160176465000090178065000100178965000120179965000220181165000140183365000170184765000230186470000250188770000230191277300250193521268582020-11-20       2020    bl uuuu     u00u1 u    #d  a1943-76927 ahttps://doi.org/10.1094/PDIS-08-20-1806-RE2DOI1 aD'AVILA, L. S.  aSensitivity of Pyricularia oryzae populations to fungicides over a 26-year time frame in Brazil.h[electronic resource]  c2020  aPublished Online:2 Nov 2020.  aThe long-term dynamics of fungicide resistance of the rice blast fungus Pyricularia oryzae was monitored by examining the reaction of the fungal field isolates, collected over a period of 26 years, to the active ingredients of commercially relevant fungicides. The in vitro sensitivity of all isolates was measured against Quinone outside inhibitors (QoI), Melanin biosynthesis inhibitors (MBI) and Sterol demethylation inhibitor (DMI) fungicides, namely azoxystrobin (QoI), tricyclazole (MBI), tebuconazole (DMI), and trifloxystrobin + tebuconazole (QoI + DMI). Over the 26-year collection period, a gradual rise in the EC50 estimates for mycelial growth sensitivity was observed for all fungicides, but most strikingly for azoxystrobin. A rise in conidial germination and appressorium formation was also noted, most markedly for azoxystrobin. Consistently, the earlier isolates were much more sensitive to the active ingredients than the more contemporary isolates. The sequencing of the amplified cyt b fragment distinguished two haplotypes, H1 and H2. Haplotype H1 (six isolates) contained the G to C transversion at codon 143 (resulting in change G143A), linked to the resistant phenotype QoI-R. Haplotype H2 (40 isolates), gathered the isolates sensitive to QoI. This work documents the gradual rise in the frequency of fungicide resistant isolates in Pyricularia oryzae rice populations on a long-term basis.  aBlast disease  aFungicides  aPyricularia  aRice  aArroz  aBrusone  aDoença de Planta  aFungicida  aOryza Sativa  aPyricularia Oryzae1 aFILIPPI, M. C. C. de1 aCAFÉ-FILHO, A. C.  tPlant Disease, 2020.