Resumo -Apesar da extensa área cultivada no Brasil e da crescente demanda sobre informações acerca do controle de plantas daninhas, poucos trabalhos são encontrados na literatura relatando a eficácia e a seletividade de herbicidas para a cultura do feijão-caupi (Vigna unguiculata). Diante disso, conduziu-se este trabalho com o objetivo avaliar a seletividade e eficácia de herbicidas para cultivares de feijão-caupi. Utilizou-se o delineamento experimental de blocos casualizados, em esquema fatorial 2 x 13, com dois cultivares (BRS Xiquexique e BRS Guariba) e 13 estratégias de manejo de plantas daninhas (1: S-metolachlor, 2: metribuzin + fluazifop, 3: imazamox + fluazifop, 4: bentazon + fluazifop, 5: imazamox + bentazon + fluazifop, 6: imazetapyr + fluazifop, 7: fomesafen + fluazifop, 8: lactofen + fluazifop, 9: chlorimuron + fluazifop, 10: chlorimuron + lactofen + fluazifop, 11: capina + fluazifop, 12: testemunha capinada e 13: testemunha sem capina). Verificou-se que não há diferença de seletividade dos herbicidas avaliados para os cultivares BRS Guariba e BRS Xiquexique; os herbicidas 1, 3, 4, 5, e 6 são seletivos para a cultura do feijão-caupi; as misturas 7 e 8 causaram severa intoxicação, prolongamento do ciclo e redução na produtividade do feijão-caupi; Os herbicidas 2, 9 e 10 não são seletivos para o feijão-caupi; as misturas de herbicidas 5 e 6 foram eficazes no controle das espécies de plantas daninhas presentes na área com produtividade equivalente à testemunha capinada; a eficácia de herbicidas ou misturas de herbicidas para o controle de plantas daninhas depende da comunidade infestante. Palavras-chaves: controle químico; plantas daninhas; Vigna unguiculata (L.) Walp Abstract -Despite the extensive cultivated area in Brazil and the growing demand for information about weed control, few studies are found in literature reporting the efficacy and selectivity of herbicides for cowpea (Vigna unguiculata). View of this, this work was developed in order to evaluate the selectivity and efficacy of herbicides for cultivars of cowpea. The experiment was conducted in a randomized block design in factorial scheme 2 x 13, with two cowpea cultivars (BRS Xiquexique and BRS Guariba) and 13 strategies for weed management (1: S-metolachlor, 2: metribuzin + fluazifop, 3: imazamox + fluazifop, 4: bentazon + fluazifop, 5: imazamox + bentazon 1 Recebido para publicação em
Macrophomina phaseolina (Tassi.). Goid is the etiological agent of one of the major diseases in cowpea bean crop, commonly known as gray rot stem. Due to the lack of registered phytosanitary products to control this disease, the search for alternative control methods is increasingly common. The objective of this study was to evaluate the effect of essential oils on mycelial growth of M. phaseolina. The oils tested were Mentha sp., Eucalyptus spp., Copaifera sp., and Lippia gracilis at concentrations of 0.4; 0.6; 0.8 and 1.0%. The work was conducted in Phytopathology Laboratory of the Federal University of Campina Grande. Daily measurements of the colony diameter were performed in two perpendicular directions until it filled the entire surface of the culture medium of one of the plates. The experiment was conducted in a completely randomized experimental design in a factorial arrangement 4 × 4 + 1 + 1, with sixteen treatments plus one negative control and one positive control, which consisted of the supplemental application in the medium (BDA) of the fungicide Sportak 450 EC (Procloraz), five replications, totaling 90 experimental plots. The data were interpreted through non-parametric analysis of variance and the means were compared by the Kruskal-wallis test, with a 5% probability of error and Scott Knott at 5% probability in cases where there were significant differences and data normality. The Mentha sp. essential oil and Lippia gracilis showed better results in inhibiting mycelial growth, while the Eucalyptus essential oil and Copaifera, although potentially promising, showed intermediate inhibition of fungal mycelial growth.
Teste de tetrazólio para avaliação da qualidade fisiológica de sementes de Vigna unguiculata (L.) Walp. 1 Tetrazolium test for evaluation of the physiological quality of seeds of Vigna unguiculata (L.) Walp.
Aims: This study aimed to evaluate the fungitoxic potential of melaleuca essential oil on the mycelial growth of Alternaria alternata under in vitro condition and the treatment of cowpea beans. Study Design: The experiments comprised completely randomized designs: Eleven treatments with five replicates on in vitro test; and six treatments with five replicates on in vivo test. Place and Duration of Study: The work was carried out at the Center for Agrifood Science and Technology of the Federal University of Campina Grande, Pombal, Brazil, since February 2018 to February 2019. Methodology: In the in vitro experiment, the essential oil was incorporated into the culture medium and poured into Petri dishes. The treatments consisted of different concentrations of the essential oil (0.0125, 0.025, 0.05, 0.1, 0.2, 0.25, 0.50, 0.75, and 1.0%), a negative control (0.0%), and a positive control (Thiram). Discs of culture medium with fungal mycelia were inoculated in the center of the plates and incubated for seven days at 27±2ºC. The percentage of mycelial growth inhibition (PGI) and the index of mycelial growth speed (IMGS) was calculated to verify the difference between treatments. In the in vivo experiment, the bean seeds were treated with different concentrations of EO (0.0, 0.2, 0.5, 1.0, and 5.0%), a negative control (0.0%), and positive control (Thiram). Seeds were inoculated with colonies of the fungus for 48 hours, and after that, we performed the seed sanity test. Results: Under in vitro conditions, all concentrations of melaleuca essential oil reduced the mycelial growth of A. alternata. The oil reached complete inhibition of fungal growth from 0.2% concentration and above. In the cowpea treatment, the essential oil had no significant control over the percentage of infected seeds. Conclusion: The melaleuca essential oil had a fungitoxic effect on the A. alternata under in vitro conditions. However, using the adopted methodology, on the cowpea bean seed treatment, the essential oil did not reduce the incidence of A. alternata.
O milho é cultivado em todo o Brasil para uso na alimentação humana e animal e como matéria prima de biocombustíveis e indústria. Sua produtividade é prejudicada pela degradação de água e solo, da qual a salinização é grave na região semiárida. Três experimentos foram realizados em solos (Argissolo, Cambissolo e Neossolo flúvico) do estado do Rio Grande do Norte para avaliar o efeito do biochar sobre a massa seca e nutrientes de plantas de milho irrigado com águas salinas. Os solos preenchiam colunas de PVC dispostas em casa de vegetação da Universidade Federal Rural do Semiárido, em Mossoró. O delineamento era inteiramente casualisado em esquema fatorial com quatro repetições. Os fatores estudados foram doses de biochar (0; 0,5; 1,0; e 1,5 %) e níveis de salinidade da água de irrigação (0,57; 2,65 e 4,5 dS m-1). O biochar foi obtido da carbonização de Prosopis juliflora (Sw.). Aos 40 dias após emergência determinou-se a massa seca da parte aérea e o teor de N, P, K, Ca e Mg das plantas. Os dados foram submetidos à análise de variância e análise de regressão. As respostas da massa seca e teores de nutrientes do milho indicam que o biochar pode mitigar a salinidade da água de irrigação, dependendo da dose aplicada e do tipo de solo.
Many watermelon (Citrullus lanatus) diseases are caused by soilborne pathogens in Brazil and worldwide. The goal of this study was to identify and quantify the frequency of phytopathogenic fungi associated with watermelon root rot and vine decline that were also present in the roots of weeds in the major watermelon production regions in the state of Rio Grande do Norte, Brazil. We collected root samples from 10 of the most prevalent weed species in 16 watermelon producing areas. The plants were identified and their frequencies in the fields were calculated. The fungi found in the weed roots were isolated and the main genera associated with watermelon vine decline were identified. We identified 13 weed species belonging to nine botanical families. The weed species with the highest frequencies found in the field were Amaranthus spinosus (25.0%), Trianthema portulacastrum (18.8%), Commelina sp. (18.8%), and Boerhavia diffusa (12.5%). The fungi Macrophomina, Rhizoctonia, and Monosporascus were isolated from the roots of the weed plants. While Macrophomina was isolated from 12 different types of plants, Rhizoctonia and Monosporascus were isolated from four and two different plant species, respectively.
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