Fluxos de emergência, épocas de aplicação de herbicidas e sistemas de manejo de plantas daninhas em cana-de-açúcar / Emergence fluxes, herbicide application timings and weed management systems in sugarcane

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The knowledge of the effects of the population dynamics and establishment velocity of weeds on the efficacy of weed management in the sugarcane crop is fundamental for the development of a rational plan of integrated weed management in the crop. Therefore, the objectives of the present research were: (i) to quantify the monthly fluxes of weed emergence year around, and to model the emergence as function of variations in temperature and water storage in the soil, in two growing areas of sugarcane of Sao Paulo state, Brazil; (ii) to evaluate the sugarcane herbicides and rates with the variation of time of herbicide application in two sugarcane growing regions of São Paulo state, Brazil; (iii) to analyze the influence of the crop rotation with sunflower x fallow, followed by soil conventional or reduced tillage soil preparation, with or without the presence of pre-planting herbicides, on the efficacy of the residual herbicides of post planting of plant cane of 12 months cycle. It was also objective of this research to evaluate the summed effect of all these pre and post planting practices on the efficacy of the herbicide mixture clomazone + (diuron + hexazinone) applied in the first sugarcane ratoon. The results of monthly emergence of ten weed species, evaluated from august 2005 to January 2007, in the sugarcane production areas of São Paulo state, Piracicaba and Ribeirão Preto, were correlated to the average monthly temperature and water storage in the soil, showing that during hot and humid months presented higher total emergencies. With regard to herbicide application timing, the results showed differences in the control between timing during the year and herbicides, indicating that the higher weed emergence intensity that occurred during the period of higher rainfall and temperature interfered on the efficacy and residual of the different treatments. The results of the experiments conducted in order to evaluate the effect of the soil preparation systems on the efficacy the herbicides applied on plant cane and first ratoon, installed in areas previously occupied by sunflower crop or fallow, indicated the weed infestation and control of the weeds Digitaria ciliaris, Amaranthus retroflexus and Bidens pilosa were differentiated in the treatment combinations of mechanical and chemical control. The use of residual herbicides in pre planting, the maintenance of the areas in fallow and the high susceptibility of the weed complex tested were the main factors of interference on the efficacy of the final control.

ASSUNTO(S)

cana-de-açúcar plantas daninhas soil tillage. weeds herbicidas - Época - aplicações herbicides season application germinação de sementes preparo do solo. sugarcane seed germination

ACESSO AO ARTIGO

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