Manejo químico de plantas daninhas em lavoura consorciada de feijão comum e mamona

Abstract

Despite the socioeconomic importance regarding castor consortium with common beans, this crop system still lacks information, above all when referred to weed chemical control. The aim of this research was to verity the influence of infesting community of weeds and its handling tactics through herbicide application at postemergency under edaphoclimatic conditions of the cerrado in Goias. The experimental outline applied was casual blocks in factorial 6 x 4 + 18, with three repetitions. Treatments were constituted of the combination of six herbicides bentazon + imazamox, clethodim, fomesafen, fluzifop-p-butil, fluzifop-p-butil + fomesafen e sethoxydim, in four doses (0,5; 1,0; 2,0 e 4,0 L ha-1 ) in consortium. Additionally, treatments for each monoculture were compared in both cultures using recommended doses of herbicide for beans harvest, and to additional witnesses (with and without hoeing). The weed community and the agronomic quality of castor and beans were evaluated, in addition to the Area Equity Index – AEI. It was concluded that predominant weed species in terms of importance were Cenchrus echinatus, Euphorbia heterophylla, Alternanthera tenella, Eleusine indica and Urochloa decumbens. The competition against weeds in beans and castor crops under consortium or monoculture was harmful to both cultures, independent the system adopted. The presence of weeds in castor culture during the whole cycle resulted in a decrease in gain of 70.7% and 71.0% in the consortium with common beans and monoculture respectively. For common beans, weeds caused a production decrease of 75.6 % and 89.7% in the consortium with castor and monoculture respectively. Herbicide bentazon + imazamox presented the best results in both crop systems. In consortium crop, the highest productive levels were reached using up doses of 2.3 and 2.1 L ha-1 , with a gain of 1700,5 kg ha-1 and 1425,3 kg ha-1 for beans and castor, respectively. In monoculture, the highs were of 1255, 3 and 2321,0 kg ha-1 , for castor and common beans respectively. Consortium presented an AEI of 1.71, revealing that consortium use for these cultures is portrayed as viable for the conditions in this experiment.