Different weed densities and control methods of organic corn production components

The objective of this work was to verify the efficiency of mechanic control methods and different populational densities of Bidens pilosa, Brachiaria decumbens and Brachiaria plantaginea and their interference in corn production components,for organic management purposes. The experiment was conducted in a green house, in a completely randomized design. with three replicates, in a factorial scheme 3x3+1. The first trial was composed by three weed densities and the second by the treatments (weed cutting at four and eight developed leaf stages, hand-weeding at four developed leaf stage, corn without weed control, and an additional treatment, corn without weed (control). The corn cultivar UFVM 100 was sowed simultaneously with the weeds in 18L pots filled with substrate (soil + organic matter). For Bidens pilosa, the greatest interference in leaf dry matter was observed in the cutting and without weed control treatments. When corn was cultivated without weeds and hand-weeded, no significant differences were observed in leaf dry matter, stem and reproductive organs, indicating that cutting was not effcient at controlling Bidens pilosa under organic corn crop conditions. When corn was planted together with B. plantaginea plants, cutting and hand-weeding provided the same dry matter accumulation; however, at higher densities (four and six plants/vase), the cutting and corn without weed control treatments were similar showing that cutting is efficient in controlling B. plantaginea at a low population density. B. decumbens showed the highest leaf dry matter reduction at a six plant/ vase density, regardless of the type of treatment.