Colletotrichum spp: SENSIBILIDADE À FUNGICIDAS E REAÇÃO À CULTIVARES DE SOJA

Antracnose e uma das doencas economicamente mais importantes da soja e de dificil controle no Mato Grosso, causando perdas significativas de produtividade. Objetivo foi verificar a sensibilidade de fungicidas e reacao de cultivares de soja a 30 isolados de Colletotrichum. A acao de sete fungicidas (azoxistrobina + ciproconazol, piraclostrobina + epoxiconazol, trifloxistrobina + protioconazol, piraclostrobina, carbendazim, fluxpiroxada + piraclostrobina e azoxistrobina) foi avaliada medindo o crescimento micelial in vitro. Todos os fungicidas afetaram o crescimento micelial, mas piraclostrobina + epoxiconazol e piraclostrobina foram os mais eficientes. Alem disso, 6 cultivares foram inoculadas com 27 isolados para analise de tombamento pre e pos-emergencia, incidencia e severidade da doenca. Os dados de incidencia e severidade foram submetidos a formula da Area Abaixo da Curva de Progresso da Doenca. Interacao significativa foi observada entre isolados e cultivares em todas as variaveis. Os isolados IT-4, IT-6, LU-3, MT-1, NU-5, PN-1, QU-2, SO-6, SO-11 e VR-1 apresentaram maior tombamento e AACPD. Exceto QU-2 todos os isolados apresentam conidios falcados. As cultivares 8866, 1179 e 9144 apresentaram menor incidencia e severidade da doenca. Palavras-chave: Glycine max; tombamento; incidencia; severidade; antracnose.   Colletotrichum spp.: Sensibility to fungicides and reaction of commercial germoplasm of soybean   ABSTRACT: Anthracnose is one of the most economically important disease of soybean and difficult to control at Mato Grosso State, causing significant yield losses. Objective was to verify the fungicides sensitivity and soybean cultivars reaction to 30 isolates of Colletotrichum. The action of seven fungicides (azoxystrobin+cyproconazole, pyraclostrobin+epoxiconazole, trifloxystrobin+protioconazole, pyraclostrobin, carbendazim, fluxpyroxade+pyraclostrobin and azoxystrobin) was evaluated measuring in vitro mycelial growth. All fungicides affected the mycelial growth development, but pyraclostrobin + epoxiconazole and pyraclostrobin were the most efficient. Besides, 6 soybean cultivars were inoculated with 27 isolates to analyze pre and post-emergence damping-off, disease incidence and severity. Incidence and severity data were submitted to the formula Area Under the Disease Progress Curve. Significant interaction was observed between isolates and cultivars in all variables. Isolates IT-4, IT-6, LU-3, MT-1, NU-5, PN-1, QU-2, SO-6, SO-11 and VR-1 showed higher damping-off and AUDPC. Excepting the QU-2, all isolates have falcate conidia. Cultivars 8866, 1179 and 9144 presented the lowest disease severity and incidence. Keywords: Glycine max; damping-off; incidence; severity; anthracnose.