Alexandre Dinnys Roese

Variabilidade fisiológica em populações de Meloidogyne paranaensis

Physiological variability of two populations of Meloidogyne paranaensis Two populations of Meloidogyne paranaensis, one from soybean plants (Mp-s) and another from coffee plants (Mp-c) were studied to compare their ability in reproducing on different hosts. Mp-s was able to reproduce more than Mp-c on tomato plants and on two soybean cultivars, but Mp-c showed a higher reproduction factor on coffee plants. On tomato ‘Santa Clara’, both populations reproduced significantly more than on other hosts, but no difference was detected between the soybean cultivars ‘MS/BR 34’ and ‘Fepagro RS 10’. However, a larger number of populations should be studied. Additional keywords: Glycine max, host, virulence of population, root-knot nematode.

Espaçamento entre linhas e severidade da ferrugem-asiática da soja

ABSTRACT A ferrugem-asiatica da soja, causada pelo fungo Phakopsorapachyrhizi Syd. & P.Syd., tem sido, desde sua deteccao no Brasil (25),um dos principais desafios fitopatologicos para essa cultura. Ate omomento, a unica forma de controle da doenca, apos sua instalacao nalavoura, e por meio da aplicacao de fungicidas, o que onera os custosda lavoura. Alem disso, o seu uso continuo, como unica estrategia demanejo, pode causar a selecao de patogenos resistentes ou menossensiveis aos fungicidas utilizados e, por conseguinte, a ineficienciado controle da doenca, com a aplicacao exacerbada de fungicidas eelevacao dos custos de producao.Dessa forma, e necessaria a combinacao de outras praticas agricolaspara o controle mais efetivo das doencas, a fim de garantir a eficienciaeconomica e ambiental da agricultura. Neste contexto, a adocao domanejo integrado torna-se uma estrategia adequada para atender aoproposito de eficiencia e sustentabilidade no controle de doencas. Noentanto, pouco avanco se obteve no conhecimento sobre o manejocultural da ferrugem-asiatica da soja, principalmente com relacao aoarranjo de plantas.O efeito do arranjo de plantas e do espacamento entre linhas desemeadura tem sido estudado por diversos pesquisadores para asmais variadas culturas (3, 4, 5, 8, 11, 12, 13, 14, 15, 16, 17, 22). Nacultura da soja, o espacamento entre linhas interfere na populacao ecrescimento de plantas daninhas (3), no indice de area foliar, navelocidade de fechamento das entrelinhas (13) e no rendimento degraos (12, 14). No entanto, pouco se tem estudado sobre o efeito deespacamento entre linhas na severidade de doencas, principalmente daferrugem-asiatica da soja, exceto pelos trabalhos realizados porMadalosso et al. (15) e Soares & Lonien (22).Sabe-se que o desenvolvimento de uma doenca depende dainteracao entre planta, agente patogenico e fatores ambientais (1, 2, 7,20). Portanto o ambiente, representado tanto pelas condicoesmeteorologicas como pelo micro clima, e um fator relevante nesta

TRANSMISSÃO PLANTA-SEMENTE DE Colletotrichum truncatum EM SOJA

A antracnose pode afetar todas as fases de desenvolvimento das plantas e a qualidade fisiologica das sementes de soja, as quais funcionam como veiculo de transmissao desses fungos fitopatogenicos. Neste contexto, o objetivo do trabalho foi avaliar a transmissao de Colletotrichum truncatum de plantas de soja infectadas para as sementes, em diferentes epocas e intensidades de ocorrencia da doenca. O experimento foi conduzido em câmara de crescimento de plantas na Embrapa Agropecuaria Oeste, em Dourados-MS. Os tratamentos foram compostos por: (1) testemunha sem inoculacao do patogeno; (2) inoculacao do patogeno no estadio vegetativo – V1; (3) inoculacao do patogeno no estadio reprodutivo – R2; (4) inoculacao do patogeno no estadio reprodutivo – R5; (5) inoculacao do patogeno no estadio vegetativo – V1 e reprodutivo – R2 e R5. Foram avaliados: o numero de graos por planta, a massa de graos, a porcentagem de vagens lesionadas e a transmissao do patogeno das plantas para as sementes. As inoculacoes de C. truncatum nos diferentes estadios fenologicos da soja nao interferem na produtividade da cultura. As plantas de soja sao mais susceptiveis a formacao de lesoes nas vagens na fase de formacao e enchimento de graos. Tanto as epocas, como a intensidade de ocorrencia da doenca, interferem na transmissao de C. truncatum da planta para a semente.

Occurrence period, severity and management of powdery mildew and rust in Jatropha curcas

Jatropha curcas L. has been studied with the aim of attending the bioenergy demand in Brazil. In this study, the time of occurrence, the severity, and the control of powdery mildew and rust in a commercial crop were investigated. During the evaluation period, powdery mildew was first observed soon after Roese, A.D.; Zeviani, W.M.; Oliveira, H.N.; Silva, C.J. Occurrence period, severity and management of powdery mildew and rust in Jatropha curcas. Summa Phytopathologica, v.44, n.3, p.274-277, 2018. the onset of the raining period in October. Rust was first observed in April. Metarhizium anisopliae, Azadirachta indica oil, J. curcas oil, and the fungicide triadimenol were efficient in controlling powdery mildew. None of these products nor potassium silicate did control rust.

Microclimate in agrosilvopastoral system enhances powdery mildew severity compared to agropastoral and non-integrated crop

While integrated crop-livestock systems including trees have received more attention during the last two decades, the epidemiology of plant diseases in these production systems is still poorly understood. Microclimatic modifications due to the type of cropping system adopted may affect the epidemic patterns. This work aimed to evaluate whether powdery mildew severity on oats (Avena strigosa and A. sativa) and on soybean (Glycine max) are affected by the cropping system and which microclimatic factors are associated with disease development. A long-term experiment was conducted to compare three systems: agropastoral (AP), agrosilvopastoral (ASP) and non-integrated crop (CO). Two rates of nitrogen (N) were applied for AP and ASP. Powdery mildew severity on oats in ASP was approximately 20× greater than in the others systems. On soybean, powdery mildew varied across systems but it was more severe in ASP, with at least 4× greater disease severity than in the other systems. Likewise, conidia of Microsphaera diffusa collected in spore traps in ASP were consistently higher than in the others systems. ASP showed shorter leaf wetness duration, higher daylight relative humidity (RH), and lower temperature amplitude compared with the other systems. Multiple regression analysis showed that leaf wetness duration and daylight RH explained best the disease variation on soybean. Our data suggest that microclimatic conditions in the ASP system are likely the main drivers of more severe powdery mildew epidemics.

First report of root and stem rot of soybean caused by Phytophthora sojae in Mato Grosso do Sul State, Brazil

Kaufm. &Gerd. is a widespread problem in the southern region of Brazil,affecting most areas where soybeans are grown. However, itsoccurrence in the central region of the country is unusual. In Brazil,this disease was first observed in Rio Grande do Sul State in 1995(Costamilan et al. Ocorrencia de