Resíduo de uva e Pochonia chlamydosporia no manejo de rizoctoniose na cultura da beterraba, em casa de vegetação

Abstract

The fungus Rhizoctonia solani is a cosmopolitan pathogen, which can cause damping-off pre and post emergence seedlings. The biological control and the addition of organic compounds to the soil, and the association of both are some alternatives for the control of this disease. The objectives of this work were to evaluate the effect of different incubation periods on the soil of Pochonia chlamydosporia (Pc 13), grape residue (GR) and the association Pc 13 + GR before beet sowing and, the effect of the dose 30 g kg-1 of the antagonist P. chlamydosporia to the soil, associated or not with grape residue, in the control of the damping-off this culture caused by the fungus R. solani, in a greenhouse. The treatments tested were: Control (R. solani), P. chlamydosporia + R. solani (Pc 13), grape residue + R. solani (GR) and P. chlamydosporia + grape residue + R. solani (Pc 13 + GR). First, the soil was infested with the fungus R. solani, which remained for five days. After the respective treatments were added, which remained incubated for 14 and 21 days before sowing, and 10 days in the experiment containing the dose 30 g kg-1 of Pc. Subsequently, the soil was placed in 250 g pots and the experiment was set up in a completely randomized design (CRD), with five replications. Then beet seeds were sown (cultivation I). Seedling emergence and damping-off was evaluated for 21 days. After the end of the evaluations, a second sowing (cultivation II) was carried out, and the same evaluations were carried out. The treatments Pc 13 and Pc + GR showed the best emergence of beet seedlings, when the treatments were incubated for 14 and 21 days, before sowing in crops I and II. For the seedling damping-off variable, only in culture I, the Pc 13 treatment, at 14 and 21 days of incubation, presented the best disease control. The increase in the amount of P. chlamydosporia inoculum, and incubated in the soil for 10 days before sowing, did not increase the efficiency of the control of seedling damping-off.