Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-16T14:00:28Z No. of bitstreams: 1 Alba Valeria da Silva Pereira.pdf: 458155 bytes, checksum: 80e5a16e6ef2e1ee3b97cac4fbc53703 (MD5) / Made available in DSpace on 2017-02-16T14:00:28Z (GMT). No. of bitstreams: 1 Alba Valeria da Silva Pereira.pdf: 458155 bytes, checksum: 80e5a16e6ef2e1ee3b97cac4fbc53703 (MD5) Previous issue date: 2009-03-16 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Application of fungicide is the main measure of management to stem-end rot and there is no information on the sensitivity and on the fitness costs arising from the reduction in sensitivity of its causal agent, Lasiodiplodia theobromae. One hundred and twenty monosporic isolates collected in producing areas of the Northeast region of Brazil, were divided into six populations. We evaluated the in vitro sensitivity (inhibition of mycelial growth) of the isolates to class the fungicides belonging to two groups: benzimidazoles and sterol demethylation inhibitors (DMIs). We also evaluated the fitness of isolates with different levels of sensitivity the fungicides both in vitro and in vivo (mycelial growth and aggressiveness). The average EC50 for DMIs ranged from 0,141 to 4,054, 0,045 to 0,691 and from 0,001 to 1,529 for tebuconazole, prochloraz and imazalil, respectively. The level of sensitivity to DMIs did not differ among populations. For the benzimidazoles EC50 of 91.6% of the isolates ranged from 0,002 to 0,14 and 0,36 in 1,272 (benomyl and thiabendazole,respectively).The 8.4% isolates, classified as not sensitive (NS) were not inhibited at the highest concentration evaluated (100μg ml of a.i-1). All NS isolates were from the same population. The aggressiveness of NS isolated was lower. / A aplicação de fungicida é a principal medida de manejo para podridão peduncular e não há informações sobre a sensibilidade e custos adaptativos decorrentes da redução de sensibilidade do seu agente causal, Lasiodiplodia theobromae. Cento e vinte isolados monospóricos, coletados em áreas produtoras da região Nordeste do Brasil, foram divididos em seis populações. Avaliou-se a sensibilidade in vitro (inibição de crescimento micelial) dos isolados aos fungicidas das classes dos benzimidazois e inibidores da biossíntese de ergosterol (IBEs) e a adaptabilidade in vitro e in vivo (crescimento micelial e agressividade) de isolados com níveis distintos de sensibilidade aos fungicidas testados. A CE50 média para os IBEs variou de 0,141 a 4,054, 0,045 a 0,691 e 0,001 a 1,529 para o tebuconazol, prochloraz e imazalil, respectivamente. O nível de sensibilidade aos IBEs não diferiu entre populações. Para os benzimidazóis a CE50 de 91,6% dos isolados variou de 0,002 a 0,14 e 0,36 a 1,272(benomyl e tiabendazol, respectivamente). Os 8,4%, classificados como não sensíveis (NS), não foram inibidos na maior concentração avaliada (100μg de i.a. ml-1). Todos os isolados NS foram oriundos de uma mesma população. A agressividade dos isolados NS foi menor. Para os IBEs, não foi detectado nenhum custo adaptativo.

This study was undertaken to determine the sensitivity of grape downy mildew (DM, Plasmopara viticola) and powdery mildew (PM, Erysiphe necator) to commonly used single-site fungicides in Virginia and nearby states. DM and PM isolates were collected from 2005 to 2007. In grape leaf disc bioassays, 92% of the DM isolates were QoI (azoxystrobin)-resistant, but none were resistant to mefenoxam. Eighty-two percent of the PM isolates were QoI-resistant, but none were resistant to boscalid and quinoxyfen. The frequency of the G143A point mutation, which confers high levels of QoI resistance, was quantified in DM and PM isolates by real-time PCR. Most of the QoI-resistant DM and PM isolates contained >95% of the 143A allele. QoI-sensitive DM isolates contained less than 1% of 143A. One out of 145 and 14 out of 154 QoI-resistant DM and PM isolates (able to grow on azoxystrobin concentration ï ³ 1 µg/ml), respectively, contained less than 1% 143A. Most PM isolates exhibited reduced sensitivity to five DMI fungicides when compared to a sensitive subgroup (n=9) and compared to published reports for unexposed populations; the resistance factor (median EC50 of the entire isolate collection divided by median EC50 of sensitive subgroup) was highest for tebuconazole (360) and myclobutanil (350), followed by triflumizole (79), triadimefon (61), and fenarimol (53). Sensitivities to all five DMI fungicides, but also azoxystrobin, were moderately to strongly correlated (pairwise r-values ranging from 0.60 to 0.88). / Master of Science in Life Sciences