The main objective of this work was to identify sources of resistance in sorghum (Sorghum bicolor) to Peronosclerospora sorghi, the causal agent of downy mildew, through the evaluation of 42 sorghum genotypes under natural infection in the field. Genotypes were planted in single row plots between two rows of the susceptible line SC283, planted 30 days before, to act as spreader rows, in two separate nurseries. The experimental design was a completely randomized block design with three replications. Sorghum genotypes CMSXS156, CMSXS157, CMSXS243, TxARG-1, 8902, 9902054, 9910032, 9910296, Tx430, QL-3, SC170-6-17, CMSXS762 and BR304 were classified as highly resistant in both nurseries. Among these, SC170-6-17 and 9910296 showed 0% systemic infection. Results indicated the possible occurrence of different pathotypes of P. sorghi in the two nurseries.

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RESUMOO agente etiológico do míldio do sorgo, Peronosclerospora sorghi, infecta as culturas do sorgo (Sorghum spp.) e do milho (Zea mays). Esse patógeno encontra-se disseminado em muitas regiões tropicais e subtropicais do mundo e pode ocasionar danos significativos na produção de sorgo quando as condições climáticas são favoráveis à sua ocorrência e em cultivares de alta susceptibilidade. No Brasil, antes restrito aos estados da região Sul, o míldio foi registrado também nos estados da região Sudeste e Centro-Oeste, causando prejuízos principalmente em áreas de produção de sementes. O cultivo de genótipos resistentes é o método mais eficiente para o controle da doença. Entretanto, essa estratégia é dificultada pela alta variabilidade genética apresentada pelo patógeno. Essa revisão aborda aspectos da taxonomia, biologia e distribuição geográfica do míldio do sorgo e discute questões relacionadas com a sua epidemiologia e controle, enfatizando estratégias que utilizam resistência genética.Palavras-chave adicionais: Straminipila, Sclerosporales, oomiceto, fitodoença, epidemiologia, controle, resistência. ABSTRACT Peronosclerospora sorghi, the causal agent of sorghum downy mildewThe causal agent of sorghum downy mildew, Peronosclerospora sorghi, is a pathogen of sorghum species (Sorghum spp.) and corn (Zea mays). The pathogen is disseminated in many tropical and subtropical regions all around the world, causing considerable losses when conditions are favorable for its development or susceptible cultivars are used. Within Brazil it was initially restricted to the Southern region but has now also spread to the Southeast and Middle-West, causing significant losses specifically in areas of seed production. The use of resistant genotypes is the most efficient method to control the disease. Nevertheless, a high genetic variability of the pathogen makes it difficult to use resistant cultivars. This revision considers aspects of taxonomy and biology of sorghum downy mildew and discusses questions related to geographic distribution, epidemiology and control, focusing on strategies that use genetic resistance.