The fungus Sclerotinia sclerotiorum, causal agent of white mold disease on several economically important crops, such as bean, soybean, and cotton, is commonly disseminated through seeds and can cause high losses on their quality and in productivity of these species. The aim of this study was assessing the effects of different initial inoculums potentials of this fungus on common bean seeds using two different strains of the fungus and two genotypes of common beans (Pérola and Ouro Negro) artificially inoculated. Seeds were sown on soil and the cultivation was performed under controlled environmental conditions favorable to development of the white mold disease. Variables assessed were: germination; seed health; emergence speed index; initial and final seedling number; and dry weight of aerial parts and roots. It was found that with the gradual increase in inoculum potential in the seeds also occurred gradual reduction in the values of: germination; emergence speed index; seedling stand; and length and dry mass of aerial parts and roots. These results show the importance of initial inoculum potential of S. sclerotiorum present in common bean seeds, as much in disseminating the pathogen as on direct damages caused in field by reducing productive potential of the emerged plants.

-Maize seeds, infected by Stenocarpella species, are important sources of inoculum for the introduction and dissemination of stalk and ear rot and macrospore leaf spot diseases. the use of healthy seeds is an important strategy for the preventive control of these diseases. However, one of the difficulties in the health quality control programs for maize seeds is the availability of a reliable and quick method for detecting these fungi during routine seed analyses. Therefore, the objective of the present study was to investigate the possibility of using the PCR technique as an alternative method for accurately detecting these pathogens in maize seed samples. Maize seeds were kept in contact with S. maydis colonie developed in PDA media containing mannitol at -1.4 MPa for 72 h. the seed samples used in this study were prepared with infected seeds at incidences of 100, 20, 10, 2, 1 and zero %.the primers used were able to detect S. maydis fungi in association with seeds with a maximum of 2% , however those primers were not able to differentiate between the two species.Index terns: fungus, molecular detection, stalk and ear rot, macrospore leaf spot.Sensibilidade da técnica PCR na detecção de Stenocarpella sp. associados às sementes de milho RESuMo -Sementes de milho infectadas por Stenocarpella são importantes fontes de inóculo para a introdução e disseminação da podridão do colmo e da espiga e mancha foliar de macrospora em campos de produção. o uso de sementes sadias constitui uma importante estratégia para o controle preventivo dessas doenças. A disponibilidade de métodos rápidos para a detecção desses fungos em análises de rotina é uma das dificuldades em programas de controle de qualidade de sementes de milho, já que o método utilizado demanda longo tempo e sua identificação é bastante subjetiva. o objetivo desse trabalho foi investigar o uso da técnica PCR para a detecção desses patógenos em sementes de milho. Para isto sementes de milho inoculadas com S. maydis foram misturadas a sementes sadias de modo que formassem lotes com incidências de 100, 20, 10, 2, 1 e zero%. o par de primers utilizado para detectar S. maydis foi capaz de detectar o máximo de 2% de incidência, todavia os primers não foram suficientes para diferenciar as duas espécies.termos para indexação: fungo, detecção molecular, podridão do colmo e da espiga, mancha foliar de macrospora.

Maize seeds infected by Stenocarpella macrospora can cause stalk and ear rot and leaf spot. Transmission of this pathogen through seeds may vary according to the cultivar, climatic conditions, and virulence of the pathogen among other factors. The aim of this study was to assess the transmission rate of S. macrospora from seeds of the maize cultivars C1-RB9308YG and C2-RB9108 using artificially infected seeds grown under two temperatures (20 ºC and 25 ºC). Seeds were inoculated by the osmotic conditioning method for 24 h (inoculum potential - P1), 48 h (P2), 72 h (P3) and 96 h (P4). After inoculation, 25 seeds were distributed individually in plastic cups with substrate, with 4 replicates per treatment. At the end of twenty-eight days of daily assessments, all plants were analyzed for the presence of the pathogen by biological methods, and some were sampled at random and analyzed Bio-PCR. The maximum percentages of dead seeds/seedlings in pre-emergence were 74.5% and 82.5% for P3 and P4, respectively. The highest total rate of transmission of the pathogen under study was 85.8% for seeds of the cultivar C1 at the highest inoculum potential (P4), grown at the temperature of 20 ºC.

-Sclerotinia sclerotiorum, the etiological agent of the "white mould" in soybean, is responsible for severe losses in this crop and soil contamination. The introduction and dissemination of the disease can made through the use of seed lots contaminated with sclerotia and by seeds infected by mycelium. Therefore, seed health quality is one aspect to be monitored by means of health testing before to sowing time. In this study conventional and quantitative PCR techniques were used to assess their viability to detect S. sclerotiorum in artificially and naturally infected soybean seed samples. For that, seeds were inoculated by osmotic conditioning technique for 0, 24, 48 and 72 hours of contact of the seed with the fungal colony and mixed with healthy seeds generating incidence levels of 1, 2, 10, 20 and 100% for each incubation time. The cPCR was sensitive to detect S. sclerotiorum in samples with at least incidence 1% inoculated for 72 hours while the qPCR detected the pathogen in all incidence/inoculum potential combinations. The conventional PCR was able to detect 0.25% of the incidence of S. sclerotiorum in soybean seed lots naturally infected added a preincubation step.Index terms: seed healthy, molecular detection, seed borne pathogen, white mould.Detecção de Sclerotinia sclerotiorum em sementes de soja pelas técnicas de PCR convencional e quantitativo RESUMO -Sclerotinia sclerotiorum causador do "mofo branco" na cultura da soja, é responsável por redução da produção e contaminação do solo. A introdução e disseminação da doença podem se dar pelo uso de sementes contaminadas com escleródios e por sementes infectadas pelo micélio. A qualidade das sementes deve ser monitorada por testes de sanidade antes da semeadura. Neste estudo foram utilizadas técnicas de PCR convencional e quantitativo para avaliar a viabilidade de uso das mesmas para a detecção de S. sclerotiorum em amostras de sementes de soja artificialmente e naturalmente infectadas. Para isso, as sementes foram inoculadas usando a técnica do condicionamento osmótico por 0, 24, 48 e 72 horas de contato das sementes com a colônia do fungo e misturadas à sementes sadias gerando incidência de 1, 2, 10, 20 e 100% para cada tempo de incubação. A técnica de cPCR foi sensível para detectar S. sclerotiorum em amostras com, no mínimo, incidência de 1% inoculadas por 72 horas, enquanto que com o qPCR foi possível detectar o patógeno em todas as combinações incidência/potencial de inóculo. A PCR convencional foi capaz de detectar 0,25% de incidência de S. sclerotiorum em lotes de sementes de soja naturalmente infectados adicionando-se uma etapa de pré-incubação das sementes.Termos para indexação: sanidade de sementes, detecção molecular, patógeno de sementes, mofo branco.

At post-harvest period, quality of corn seeds may be influenced by several important factors such as: presence of harmful microorganisms, chemical treatments, host species genotype and storage conditions. The objective of this study was to evaluate the performance of corn seeds, hybrids 2B 688 and 2B 710, with high incidence of fungus Fusarium verticillioides and treated with mixtures of fungicides thiophanate-methyl + pyraclostrobin (50 mL a.i .100 kg-1 of seeds) and carbendazim + thiram + micronutrients (100 mL a.i .100 kg-1 of seeds) during six months storage. Performance assessments of seeds were carried out at 0, 30, 60, 90, 120, and 180 days storage. The incidence of F. verticillioides, as well as physiological quality, germination, vigor, stand of plants, emergence speed index, and dry matter weight were assessed. It has been verified that seed treatment with fungicide mixtures was efficient for ensuring seed physiological quality of both genotypes and to reduce incidence of F. verticillioides on treated seeds. By contrast, analysis between treatments with fungicides, within each period assessed and each treatment as compared to control along storage period was verified clear benefits on emergence of seeds after treatment with fungicides.