Distribuição, diâmetro de gotas e fitoxicidade de herbicidas aplicados em mudas de eucalipto com pontas de indução de ar

Abstract

Resumo -As pontas de pulverização são responsáveis pela formação das gotas, sendo que cada tipo de ponta exerce uma função diferente, com características próprias relacionadas à deposição de gotas de acordo com alvo que se deseja atingir. Este trabalho teve como objetivo avaliar a distribuição, diâmetro de gotas e fitotoxicidade dos herbicidas glyphosate e isoxaflutole, aplicados em mudas de eucalipto com pontas de indução de ar (AIUB 04 e TTI 110 04). O espectro do diâmetro de gotas foi determinado em analisador de tamanho de partículas por difração de luz laser. Os perfis de distribuição volumétrica foram avaliados em mesa de deposição, para a coleta da calda pulverizada. As avaliações visuais da fitotoxicidade dos herbicidas foram realizadas aos 7, 14, 21 e 28 dias após a aplicação. Ao final do período experimental determinou-se a massa de matéria seca de caule e folhas. A ponta de TTI 110 04 teve maior diâmetro mediano volumétrico (DMV), menor percentual de gotas menores que 100 µm e menor coeficiente de uniformidade de gotas em comparação com a ponta AIUB 04, independentemente da calda utilizada. Para a ponta de pulverização modelo TTI 110 04, os espaçamentos de 0,45 e 0,75 cm apresentaram melhor uniformidade (coeficiente de variação menor que 10%). O modelo AIUB 04 não resultou em nenhum coeficiente de variação aceitável. A aplicação de glyphosate com a ponta AIUB 04 aumentou a fitointoxicação. O herbicida isoxaflutole mostrou-se seletivo ao eucalipto. Palavras-chaves: tecnologia de aplicação, espaçamento entre pontas, seletividade, caracterização de gotas Abstract -The spray nozzles are responsible for the formation of droplets, each nozzle type exerts a different function, with its own characteristics related to the deposition of droplets according to the desired target. This study aimed to evaluate the distribution, droplet diameter and phytotoxicity of glyphosate and isoxaflutole herbicides applied in eucalyptus seedlings with air induction nozzles (AIUB 04 and TTI 110 04). The spectrum of droplet diameter was determined by particle size analyzer by laser light diffraction. The volumetric distribution was evaluated in deposition table to collect the sprayed volume. The visual assessments of phytotoxicity of the herbicides were carried out at 7, 14, 21, and 28 days after application. At the end of the experiment it was determined the dry mass of stem and leaves. The TTI 110 04 nozzle had greater volumetric 1 Recebido para publicação em 20/06/2014 e aceito em 01/08/2015. 2 Doutoranda, Programa de Produção Vegetal, Faculdade de Ciências Agrárias e Veterinárias/UNESP -câmpus Jaboticabal.

Using unmanned aerial vehicle for identifying the vegetative vigor and quantify the area occupied by eucalyptus sprouts after chemical weeding in the state of Bahia, Brazil

“…The map of the post-application period shows nonuniform sprout biomass (size), but in terms of vegetative vigor, the plants showed a high rate of regrowth (high NDVI, dark green color). The good health status of the sprouts indicates an intense competition for water, light, and nutrients between the sprouts and the newly planted seedlings between the planting rows (Silva et al, 2014), which requires immediate action to control the sprouts to avoid harming the development of the seedlings.…”

Toxicity of Pre-Emergent Herbicides Applied via Irrigation Water in Eucalyptus Plantation

“…ha -1 ) is applied, may be due to the efficient weed control promoted at this dose during the experimental period, resulting in higher initial crop growth, evidenced by the significant increase in the photosynthetic area of the plants, corresponding to approximately 345 leaves and 6439 cm 2 , when compared to the treatment without application. Silva et al (2014) report that isoxaflutole has residual effect on the soil, according to the dosage used, which allows the efficient control of weeds such as Brachiaria decumbens and Panicum maximum, preventing new flows of these plants.…”

“…Isoxaflutole is a systemic herbicide and its mechanism of action is based on the inhibition of carotenoid synthesis. Once in soil, water and plant, it is rapidly converted to diquetonitrile, the biologically active molecule in weed control (SILVA et al, 2014). It effectively controls monocotyledons and some dicotyledons (SILVA; SILVA, 2007).…”

Spectrum and Velocity of Droplets of Spray Nozzles With and Without Air Induction

“…The mechanis m at these nozzles follo ws the operating principle of a Venturi tube. These stand out from the other spray nozzle types because the flow rate of liquid and air are mixed inside a chamber, when passing under high pressure by the nozzle and coming into contact with the atmosphere, it forms droplets with air bubbles inside Leite & Serra, 2013;Silva et al, 2014b).…”