Despite the resistance problems in Monilinia fructicola, demethylation inhibitor fungicides (DMIs) are still effective for the disease management of brown rot in commercial stone fruit orchards in Brazil. This study aims to investigate the sensitivity of M. fructicola isolates and efficiency of DMIs to reduce brown rot. A set of 93 isolates collected from Brazilian commercial orchards were tested for their sensitivities to tebuconazole, propiconazole, prothioconazole, and myclobutanil. The isolates were analyzed separately according to the presence or absence of the G461S mutation in MfCYP51 gene, determined by allele-specific test. The mean EC50 values for G461S mutants and wild-type isolates were respectively 8.443 and 1.13 µg/ml for myclobutanil, 0.236 and 0.026 µg/ml for propiconazole, 0.115 and 0.002 µg/ml for prothioconazole, and 1.482 and 0.096 µg/ml for tebuconazole. The density distribution curves of DMI sensitivity for both genotypes showed that myclobutanil and prothioconazole curves were mostly shifted toward resistance and sensitivity, respectively. Incomplete cross-resistance was detected among propiconazole and tebuconazole in both wild-type (r = 0.45) and G461S (r = 0.38) populations. No cross-sensitivity was observed among wild-type isolates to prothioconazole and the others DMIs tested. Fungicide treatments on detached fruit inoculated with M. fructicola genotypes showed significant DMI efficacy differences when fruit were inoculated with wild-type and G461S isolates. Protective applications with prothioconazole were more effective for control of both G461S and wild-type isolates compared with tebuconazole. Curative applications with tebuconazole were most effective in reducing the incidence and lesion size of G461S isolates. Sporulation occurred only for G461S isolates treated with tebuconazole under curative and preventative treatments. The differences found among the performance of triazoles against M. fructicola isolates will form the basis for recommendations of rational DMI usage to control brown rot in Brazil.
Ao meu avô Elevítico (In memoriam), que me acolheu com todo seu amor e carinho e me motivou a ir atrás dos meus sonhos.
Dedico
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AGRADECIMENTOSA Deus por sempre me guiar por todos meus caminhos percorridos.À toda minha família, principalmente minha mãe, meus avós e minhas tias, que sempre me incentivaram e não mediram esforço para me ajudar a conquistar meus sonhos.À minha professora e orientadora Lilian Amorim pelos seus ensinamentos e por sua paciência em acompanhar o meu desenvolvimento ao longo desses quatro anos de doutorado. Ao Dr. Juan A. Navas-Cortés por aceitar me receber em sua instituição durante o meu período de permanência na Espanha e pelos seus valiosos ensinamentos em análises multivariadas.Ao CNPQ (processo 140075/2019-4) pelo auxílio financeiro durante 16 meses do Doutorado.À CAPES, pelo auxílio financeiro (código 001) durante o restante de meses do Doutorado no Brasil e também por possibilitar financeiramente a minha ida para Espanha através do programa CAPES/Print. À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) pelo apoio financeiro dos projetos em que eu tive a oportunidade de participar. À Escola Superior de Agricultura "Luiz de Queiroz" pela oportunidade concedida e também aos professores do Programa de Pós-graduação em Fitopatologia que contribuíram para a minha formação acadêmica. Ao Dr. Antônio Nogueira por todo auxílio e ensinamentos técnicos nos ensaios de trocas gasosas.À Silvia Lourenço pelo todo auxílio na condução dos experimentos e atividades do laboratório. À Profa. Dra. Beatriz Appezzato-da-Glória pelo auxílio nas análises histopatológicas.Aos colegas de pós-graduação, Renan
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