RESUMO Macrophomina phaseolina é um patógeno de solo com uma grande variedade de hospedeiros e de difícil controle por práticas culturais. O objetivo deste estudo foi quantificar a severidade da podridão das raízes (SPR) causada por M. phaseolina em cultivares de feijoeiro comum e seu impacto nos componentes de produção. Os experimentos foram conduzidos em casa de vegetação com as cultivares de feijão comum ANFC-9 Agro Norte, BRS Esteio, BRS Estilo, BRS Pérola, FTS Soberano, IPR Campos Gerais, IPR Tangará, IPR Tuiuiú, IPR Uirapurú e TAA Dama. Três isolados de M. phaseolina obtidos de plantas infectadas de feijão, soja e milho foram inoculados nas cultivares de feijão. No estádio fenológico R9 da maturidade da colheita de grãos foram avaliados o SPR e os componentes de produção de massa seca de raízes (MSR), número de legumes por planta (NLP), número de grãos por planta (NGP) e massa de grãos por planta (MGP). Todas as cultivares de feijão foram suscetíveis a M. phaseolina, apresentando redução no NLP, NGP e MGP. A SPR foi superior a 75%, independentemente da origem dos isolados. Na média das cultivares houve decréscimo significativo de 54,3% na MSR quando comparadas aos tratamentos controle. As cultivares IPR Tangará, ANFC-9 Agro Norte, BRS Esteio, BRS Pérola e ‘FTS Soberano’ obtiveram redução em pelo menos um dos componentes da produção enquanto a cultivar IPR Tangará em todos. Observouse decréscimo médio de NLP, NGP e MGP de 7,9%, 7,6% e 7,2%; 13,4%, 12,8% e 6,7%; e 14,2%, 12,9% e 10,1%, considerando os isolados obtidos de feijão, soja e milho, respectivamente.

ABSTRACT Macrophomina phaseolina is a soilborne pathogen with a wide range of hosts and its control through agricultural practices is difficult. The aim of this study was to quantify the severity of root rot (SRR) caused by M. phaseolina in common bean cultivars and its impact on yield components. The experiments were carried out under greenhouse conditions with the common bean cultivars ‘ANFC-9 Agro Norte’, ‘BRS Esteio’, ‘BRS Estilo’, ‘BRS Pérola’, ‘FTS Soberano’, ‘IPR Campos Gerais’, ‘IPR Tangará’, ‘IPR Tuiuiú’, ‘IPR Uirapurú’ and ‘TAA Dama’. Three isolates of M. phaseolina obtained from infected plants of common bean, soybeans and maize were inoculated in the common bean cultivars. In the phenological stage R9 of grain harvest maturity, the SRR and the yield components of root dry mass (RDM), number of pods per plant (NPP), number of grains per plant (NGP) and grain mass per plant (GMP) were assessed. All common bean cultivars were susceptible to M. phaseolina, showing a reduction in NPP, NGP and GMP. SPR was greater than 75%, regardless of the origin of isolates. Considering the average of cultivars, there was a significant decrease of 54.3% in RDM, compared to control treatments. The cultivars ‘IPR Tangará’, ‘ANFC-9 Agro Norte’, ‘BRS Esteio’, ‘BRS Pérola’ and ‘FTS Soberano’ had a decrease in at least one yield component, while a reduction occurred in all components for cultivar ‘IPR Tangará’. There was an average decrease in NPP, NGP and GMP of 7.9%, 7.6% and 7.2%; 13.4%, 12.8% and 6.7%; and 14.2%, 12.9% and 10.1%, considering the isolates obtained from beans, soybeans and maize, respectively.

ABSTRACT Stalk rots compromise the translocation of water and nutrients, affecting grain filling. This study aimed to quantify the incidence of stalk rots in corn hybrids depending on sowing time and nitrogen topdressing rate, and to assess any correlation with grain yield. The experiment was conducted under field conditions in Atalanta, Santa Catarina state, Brazil, using a split-split-plot randomized block design. The hybrids AG 9025 PRO3 (super-early) and 30F53 VYH (early) were sown in the preferential (September 20) and late (December 5) sowing seasons with four nitrogen rates (0, 150, 300, and 450 kg·ha–1). The population density was 75,000 plants·ha–1 andthe nitrogen topdressing was carried out at the V4, V8, and V12 stages. The fungus Colletotrichum graminicola predominated in both hybrids and its presence was negatively correlated with stalk diameter and yield. The hybrid AG9025 PRO3 was more susceptible to stalk rot (35.1%) than the hybrid 30F53 VYH (8.8%). A higher incidence of stalk rot was observed in the late sowing season (31.1%) than in the preferential sowing season (11.2%). A decrease in the incidence of stalk rot was observed in the hybrid AG9025 PRO3 as nitrogen rates increased, but this behavior was not clearly observed in the hybrid 30F53 VYH.

RESUMO: O fungo Fusarium graminearum foi um dos primeiros patógenos descritos na cultura do arroz, no entanto, no Brasil, não há descrição de sua ocorrência em panículas. O objetivo desse estudo foi descrever os sintomas ocasionados pela infecção de F. graminearum em grãos de arroz irrigado. O experimento foi conduzido, em casa de vegetação, duas vezes, com a cultivar de arroz irrigado SCS 121CL e o Híbrido INOV CL no estádio R4 (florescimento). Dois isolados de espécies do complexo Fusarium graminearium, 15A (F. graminearium - 15ADON) e FmNiv (F, meridionale - Nivalenol) foram inoculados em panículas por aspersão de macroconídios, com acompanhamento da evolução dos sintomas até a colheita. Não houve diferença entre os isolados. Pontos de coloração parda foram observados nas glumas três dias após inoculação, evoluindo, posteriormente, para lesões de coloração marrom-claro de tamanho e forma irregular. Houve escurecimento total da gluma com coloração arroxeada quando os grãos encontravam-se no estádio de enchimento de grão (R6). Na maturação de colheita a gluma dos grãos apresentava coloração marrom-escuro. Grãos severamente infectados mostraram-se chochos e quebradiços.

ABSTRACT: The fungus Fusarium graminearum was one of the first pathogens described as causing infections in rice; however, in Brazil, there is no description of its occurrence in panicles. The present study aimed to describe the symptoms caused by F. graminearum infection in irrigated rice grains. The experiment was conducted in a greenhouse in duplicate using the irrigated rice cultivar SCS 121CL and hybrid INOV CL at the R4 (flowering) stage. Two isolate of Fusarium graminearium species complex 15A (F. graminearium - 15-ADON) and FmNiv (F. meridionale - Nivalenol), was inoculated onto panicles by spraying with macroconidia and the development of symptoms was monitored until harvest. There was no difference in symptoms among isolates. Light brown spots were observed in the glumes three days after inoculation. These later evolved into brown lesions of irregular shape and size. The glume darkened to purple when the grains were in the filling stage (R6). On maturation, the glume showed dark brown coloration. Severely infected grains were shriveled and brittle.