Manejo do mofo branco da soja com palhada de Brachiaria ruziziensis e Trichoderma harzianum 1306

Abstract

The objective of this study was to evaluate the association of cultural practices established with soil mulch with straw of Brachiaria ruziziensis, and biological control with sprayings of 2 x 109 viable spores / mL of Trichoderma harzianum strain 1306, to decrease the inoculum density of Sclerotinia sclerotiorum, causal agent of white mold on soybeans, and the incidence of white mold. The experiment was carried out in Jataí, GO, at the Brazilian Center-West Region, in a commercial soybean field naturally infested with the pathogen, in 2006/2007 and 2007/2008 seasons. Implemented in March 2006 on plots of 630 m² in a completely randomized design with three repetitions, the presence and absence of B. ruziziensis and applications of T. harzianum in dosages 0, 0.5, 1.0 and 1.5 L.ha-1 in one or two sprayings (March and October). The soil was sampled for quantification of sclerotia in March to assess the initial inoculum, in June, and September to evaluate the viability of sclerotia on PDA medium. Field and laboratory assessments were done for viability and parasitism of S. sclerotiorum sclerotia by Trichoderma spp. and other soil microorganisms, the number of apothecia, white mold incidence and yield components. In the presence of B. ruziziensis the viability of sclerotia was lower and at 0.5 and 1.0 L.ha-1 T. harzianum strain 1306 parasitism of sclerotia was higher than the control without T. harzianum strain 1306 . In the presence of straw in Brachiaria decreased the number of apotécios. The white mold incidence of residual effects was lower in the presence of straw in doses 0.5 and 1.0 L.ha-1 T. harzianum strain 1306 . The grain yield of soybean was higher dosage of 0.5 L ha-1 T. harzianum strain 1306 .