Chemical weed control in the consortium mamona- cowpea in upland

O experimento foi conduzido em condiÃÃes de sequeiro, no perÃodo de abril a setembro de 2010, na Fazenda Lavoura Seca, QuixadÃ, CE, no intuito de avaliar a eficiÃncia dos herbicidas diuron (diuron SC), pendimethalin (herbadox 500), e metolachlor (dual gold), em trÃs doses, no controle das plantas daninhas no consÃrcio mamona e feijÃo caupi e o efeito fitotÃxico desses herbicidas sobre a mamona e o feijÃo caupi. No consÃrcio utilizou-se a mamona, cv. BRS ENERGIA e o feijÃo caupi, cv. EPACE 10. As culturas foram plantadas em fileiras alternadas, com os arranjos seguintes: mamona em fileiras no espaÃamento 1,00 x 1,00 m, com uma fileira de feijÃo caupi entre duas fileiras de mamona. As fileiras de feijÃo caupi distaram 0,5 m das de mamona e as plantas dentro da fileira de 0,25 m. Os herbicidas e respectivas doses de ingrediente ativo avaliados foram: metolachor nas doses de (600 g ha-1, 1200 g ha-1 e 1800 g ha-1) diuron (1000 g ha-1, 2000 g ha-1 e 3000 g ha-1) e pendimenthalin (500 g ha-1, 1000 g ha-1 e 1500 g ha-1). Utilizou-se um delineamento experimental de blocos ao acaso, com arranjo fatorial e dois tratamentos adicionais (3x3+2) com 4 repetiÃÃes, exceto na anÃlise da matÃria seca das plantas daninhas onde utilizou-se um arranjo fatorial (3x3+1) com um tratamento adicional (testemunha sem capina). Os herbicidas diuron, pendimethalin e metolachlor foram nÃo seletivos a cultura da mamona causando atrasos na emergÃncia de plÃntulas, crescimento inicial, reduÃÃo dos estandes inicial e final, reduÃÃo da altura das plantas e decrÃscimos significativos na produtividade da cultura. No entanto, os mesmo herbicidas foram seletivos à cultura do feijÃo caupi, nÃo alterando a altura das plantas, nÃmero de vagens por planta e estande final. Quanto ao controle das plantas daninhas, avaliado atravÃs do peso da matÃria seca, os melhores resultados foram obtidos com o metolachor e diuron com destaque para a dose de 1800 g de i.a ha-1 do metolachlor, que reduziu de forma significativa o peso seco das plantas daninhas.The experiment was conducted under rainfed conditions in the period April to September 2010, at Farm Lavoura Seca, QuixadÃ-CE, in order to evaluate the efficiency of diuron (Diuron SC), pendimethalin (herbadox 500), and metolachlor ( Dual Gold) in three doses on weed control in cowpea and castor bean intercropping and the phytotoxic effect of herbicides on the castor bean and cowpea. In the intercropping used the castor bean, cv. BRS ENERGY and the cowpea, cv. EPACE 10. The crops were planted in alternate rows, with the following arrangements: castor beans in rows with spacing 1.00 x 1.00 m, with a row of cowpea between two rows of castor oil. The rows of cowpea were far from castor 0.5 m and the plants within the row of 0.25 m. The herbicides and doses of active ingredient were: metolachor at doses (600 g ha-1, 1200 g ha-1 and 1800 g ha-1) diuron (1000 g ha-1, 2000 g ha-1 and 3000 g ha-1) and pendimenthalin (500 g ha-1, 1000 g ha-1 and 1500 g ha-1). We used a randomized block design, with factorial arrangement and two additional treatments (3x3 +2) with four replications, except in the analysis of dry matter of weeds where we used a factorial arrangement (3x3 +1) with a additional treatment (control without weeding). The herbicides diuron, metolachlor and pendimethalin were not selective castor bean crops causing delays in seedling emergence, early growth, reducing the initial and final stands, reduced plant height and significant decreases in yield. However, the same herbicides were harmless to the crop of cowpea, not changing the plant height, number of pods per plant and final stand. As for weed control as measured by the dry weight, the best results were obtained with diuron metolachor and especially a dose of 1800 g ai ha-1 of metolachlor, which significantly reduced the dry weight of weeds