Desenvolvimento, fisiologia e ocorrência de míldio em videiras cv. BRS Margot tratadas com preparados biodinâmicos

The objective of this work was to evaluate the development, physiology and resistance to downy mildew of the BRS Margot grapevine treated with biodynamic preparations in a greenhouse. The experimental design was completely randomized with three treatments and ten replications in each treatment. The treatments were: 1) control pots with application of water in the aerial part; 2) organic treatment: application of chitosan (Fish Fértil® 200 mL.100 L-1) in the aerial part; 3) biodynamic treatment: application of biodynamic formulation silica horn (501) (4 g.60 L-1) in the aerial part and compost with formulations 502 to 507. Four leaf applications of the water, chitosan and preparation (501) were carried out in the 8 and 14 leaves separated stages in January and February (first cycle), November and December 2015 (second cycle) and two application of compost in plantation and September 2015 in the wooly bud stage. The plants were evaluated for the length and diameter of the canes, trunk, SPAD index, gas exchange and area under the disease progress curve (AUDPC). Biodynamic formulations had an effect on the development of the BRS Margot grapevine, verified by the increase of the length of the branches, CO2 assimilation, RuBisCO enzyme efficiency, chlorophyll content (SPAD index) and reduced the incidence of mildew.