Survival of pathogens on soybean debris under no-tillage and conventional tillage systems

Abstract

A study was conducted in the subtropical area of Southern Brazil to determine the survival of pathogens in soybean residues under conventional and no-tillage cultivation systems from March to September of 1998 and 1999. The pathogens most frequently isolated were Colletotrichum truncatum, Phomopsis spp., Cercospora kikuchii, Fusarium spp., Macrophomina phaseolina, and Rhizoctonia solani. Other fungi isolated were Myrothecium roridum, Penicillium sp., Chaetomium sp., Epicoccum sp., Corynespora cassiicola and Trichoderma sp. The percent of survival of each pathogen varied according to the month and the year. Survival of C. truncatum, Phomopsis spp. and C. kikuchii were significantly reduced (p<0.05) from the first to the last evaluation either on buried debris or maintained on the soil surface. On the other hand, M. phaseolina and Fusarium spp. were either not affected or favored by burying the debris. The frequency of recovery of Fusarium spp. increased specially in debris kept under the soil. The loss of biomass, measured by debris weight along the period of this study, showed a reduction of 44.4% in the conventional system and 34.9% in the no-tillage system in 1998, when rain was better distributed. In 1999, the reduction was 48.2% and 39.0% for the conventional and no-tillage system, respectively.Index terms: cultivation, crop residues, degradation, biomass, plant diseases. Sobrevivência de patógenos em restos de cultura de soja mantidos em sistema de semeadura direta e convencionalResumo Avaliou-se a sobrevivência de patógenos em restos de soja, em sistema de semeadura direta e convencional, entre março e setembro de 1998 e 1999, em Londrina, PR. Termos para indexação: cultivo, resíduos de colheita, degradação, biomassa, doenças das plantas.

Impact of Crop Residue and Corn-soybean Rotation on the Survival of Fusarium virguliforme a Causal Agent of Sudden Death Syndrome of Soybean

“…However, in their study they observed that the F. virguliforme population was not quantifiable from fields with wheat in rotation. Results of our microplot studies with diverse crop residue amendment are in agreement with findings of Almeida et al [29], Cotten and Munkvold [30] and Kommedahl et al [31] but differ from Marburger et al [32] for F. virguliforme.…”

“…Studies by Almeida et al [29] showed that soybean debris support increased CFU of F. solani, F. verticillioides, F. equiseti, F. dimerum and F. oxysporum, while studies of Cotten and Munkvold [30], showed that corn stalks are good residue for F. moniliforme, F. proliferatum, and F. subglutinans, and Kommedahl et al [31] showed corn roots support F. oxysporum, F. solani, and F. roseum and corn stalks support F. moniliforme. Recently, Marburger et al [32] observed no significant effect of crop rotation sequences and management (variety selection and fungicide use) on F. oxysporum and F. virguliforme.…”

Development of Sclerotium rolfsii sclerotia on soybean, corn, and wheat straw, under different soil temperatures and moisture contents

“…How the changes in tillage practices have affected the prevalence of the disease in the region is also unknown. However, Almeida et al (2001) found significant differences in stem blight incidence according to the soil management system used. These authors showed that seedling stem blight in conventional and no-till fields were significantly different.…”

Chlamydospore formation by Corynespora cassiicola

“…In Brazil, this pathogen causes serious damage on soybean (Glycine max) (Almeida et al, 2001), parthenocarpic cucumber (Cucumis sativus) (Verzignassi et al, 2003) and tomato (Lycopersicon esculentum) (Leroy & Lourd, 1989).…”