Maria do Carmo A Fernandes

Efeito de produtos químicos e biológicos sobre a mancha bacteriana, flora microbiana no filoplano e produtividade de pimentão

The effect of weekly sprayings with streptomycin sulfate + oxytetracycline (0.8 g ia L-1), copper oxychloride (2.4 g ia L-1) and Agrobio fertilizer (5%) plus a control (water) was evaluated in the control of bacterial spot, the microbial flora in the phyloplan, and over yield in three bell pepper cultivars (Magda, Cascadura Itaipu and Magali R). The study was carried out under field conditions from May to December 2002. A randomized complete block experimental design was used with four replications in a 4 x 3 factorial design. Weekly assessments were made for plant height (cm); number of stems; total number of leaves; number of fallen leaves; number of leaves with visible symptoms; damaged leaf area (severity), and yield (t ha-1). The microbial population resident in the phyloplan and fruits was quantified at the same time. There was no effect of treatments on yield, but an effect was observed on plant growth, on leaf spot and on the microbial flora. Copper oxychloride inhibited plant development, reduced number of fallen leaves and decreased the bacterial flora. Agrobio stimulated plant growth and, like streptomycin sulfate + oxytetracycline, inhibited the bacterial population, except Bacillus sp., and fungi, except Cladosporium sp. in the phyloplan. Among the genotypes, the hybrid Magali R was significantly superior in plant vigor, yield and resistance to bacterial spot. The results suggest bactericidal activity of the Agrobio under field conditions.

Ação bacteriostática do biofertilizante Agrobio in vitro

Agrobio is a biofertilizer prepared from fresh cattle manure, water, molasses and minerals, fermented under room temperature in open containers during 56 days. This product has been widely used by organic and conventional farmers throughout Rio de Janeiro State, Brazil, to control several plant pathogens of various crops. The antibiotic effect of different concentrations of Agrobio against Xanthomonas euvesicatoria, in vitro vas evaluated. Four bioassays were performed with three isolates of the bacterium. Agrobio was tested in three preparation stages (35, 85 and 115 days of fermentation) and applied raw, filtered (0,22 µm) or autoclaved (120oC/20 minutes). The effect of the treatments was assessed by the diameter of the inhibition growth halo on Petri dishes. Agrobio presented bacteriostatic effect on X. euvesicatoria regardless of the sample age or pre-treatment. Growth inhibition occurred above 5% concentration, indicating the feasibility of Agrobio, as a bacterial leaf spot control agent, in early fermentation stages (35 days). Field experiments are necessary to confirm these results.