Paraquat doses and spray volumes in desiccation Brachiaria ruziziensis before planting off-season maize

A Brachiaria ruziziensis pode contribuir na consolidação do sistema de plantio devido à alta produção de biomassa vegetal que pode ser empregada no manejo integrado das plantas daninhas. Contudo, existe escassez de informações referentes à dessecação desta forrageira, principalmente com o uso de herbicidas de ação de contato. Assim, objetivou-se avaliar diferentes métodos de manejo da dessecação da forrageira B. ruziziensis, e o efeito na cultura do milho safrinha e na supressão das plantas daninhas. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Os tratamentos foram dispostos num esquema fatorial 4 x 6 + 1, correspondente a avaliação de quatro doses do paraquat (100, 200, 400 e 800 g ha-1) em seis volumes de aplicação (69, 138, 204, 273, 342 e 411 L ha-1), além de uma testemunha sem aplicação. Para o estudo da dinâmica da população das plantas daninhas também foi utilizada uma testemunha em condição de pousio e outra somente com a cultura sem a presença de palha (capinada). Foram utilizadas pontas de pulverização modelo Turbo Teejet de jato plano simples com angulação de 90º. O paraquat foi eficiente na dessecação da B. ruziziensis até aos 14 dias após a aplicação. Após este período a rebrota da forrageira interferiu negativamente na produtividade do milho safrinha. A infestação das plantas daninhas foi reduzida nas áreas com B. ruziziensis em consorcio com o milho safrinha em relação à área em pousio.Brachiaria ruziziensis can contribute to the consolidation of the no-tillage system due to high production of biomass that can be used in integrated management of weeds. However, there is little information regarding the desiccation of this forage, particularly with the use of contact action herbicides. The present work aimed to evaluate the different management methods of desiccation of B. ruziziensis, and the effect in second season maize crop and weed suppression. The experimental design was a randomized complete block design with four replications. The treatments were arranged in a factorial 4 x 6 + 1, corresponding to evaluation of four doses of paraquat (100, 200, 400, and 800 g ha-1), six spraying volumes (69, 138, 204, 273, 342, and 411 L ha-1), and an untreated control. To study the population dynamics of weeds a control was also used in fallow condition and another with only the crop, without the presence of straw (weeded). The spray nozzle used was Turbo TeeJet simple plan jet with angulation of 90°. The paraquat was efficient in desiccation B. ruziziensis up to 14 days after application. After this period there was regrowth of forage plants interfered negatively on maize yiled. The weed infestation was reduced in areas with B. ruziziensis in crop rotation with maize in relation to fallowing areas

Selectivity and efficiency of pre-emergent herbicides on cassava crop

The chemical control of weeds stands out as an important tool for obtaining high yields in cassava crops. This study aimed at evaluating the selectivity and efficiency of pre-emergent herbicides on cassava ('Cascuda' cultivar) crop. The experimental design was randomized blocks, with ten treatments and four replications. The treatments consisted of clomazone (900 g ha-1 and 1,080 g ha-1), flumioxazin (60 g ha-1), sulfentrazone (600 g ha-1), S-metolachlor (1,920 g ha-1), clomazone + flumioxazin (900 + 50 g ha-1), clomazone + sulfentrazone (900 + 500 g ha-1) and clomazone + S-metolachlor (900 + 1,440 g ha-1), as well as a weeded and a non-weeded control. The weed community was composed by 9 families and 12 species, with the Asteraceae and Poaceae families presenting the highest number of species. The pre-emergent herbicides were selective for 'Cascuda' cultivar cassava plants. The herbicides were effective in controlling weeds, with flumioxazin (60 g ha-1), sulfentrazone (600 g ha-1), S-metolachlor (1,920 g ha-1) and the mixtures of clomazone + flumioxazin (900 + 50 g ha-1), clomazone + sulfentrazone (900 + 500 g ha-1) and clomazone + S-metolachlor (900 + 1,440 g ha-1) presenting the highest residual effect

Núcleos de Ensino da Unesp: artigos 2008

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq