Lino Roberto Ferreira

Avaliação de estratégias para redução da deriva de agrotóxicos em pulverizações hidráulicas

Pesticide spray drift is a major problem in agriculture today. Among the factors influencing drift, droplet size is of paramount importance. Thus, this work aimed to evaluate the effects of adding emulsifying vegetable oil to the pesticide emulsion and using low drift nozzles on droplet spectrum formation and, consequently, on the drift potential of fan spray nozzles. Droplet distribution was measured under controlled atmosphere, using a real time laser particle size analyzer. The droplets were generated with standard nozzles, with and without the addition of adjuvants, and with low drift nozzles, with the operating pressure ranging from 200 to 400 kPa. Also, drift was evaluated in the field, using artificial targets placed outside the application area, where droplet counting was accomplished. The results showed that both the addition of vegetable oil to the pesticide emulsion and the use of low drift nozzles altered droplet size spectra, increasing the diameter of the drops and reducing the percentage of drops subject to wind action being, thus, effective factors in drift reduction.

Manejo de plantas daninhas no consórcio de milho com capim-braquiária (Brachiaria decumbens)

The objective of this work was to evaluate the effects of nicosulfuron and atrazine mixture on weeds, corn and Brachiaria decumbens intercrops, cultivated under no-tillage and conventional tillage. Six nicosulfuron doses (0, 2, 4, 8, 16 and 24 g ha-1) in mixture with atrazine in the dose of 1.500 g ha-1 were evaluated, plus two controls, represented by both species in monocrop. Seminiferous propagation of the annual weeds was efficiently controlled by applying nicosulfuron in 8 g ha-1 in mixture with atrazine, regardless of the management systems. The perennial species (Artemisia verlotorum and Cyperus rotundus), of vegetative propagation, were not controlled by the herbicide mixture, regardless of the applied dose. Larger infestations of these species were observed under the conventional system. B. decumbens biomass was reduced in the intercrop with corn, when compared to its control in monocrop, presenting a greater reduction when submitted to the largest doses of nicosulfuron, in both planting systems. No difference was observed in the production of grains and corn straw, in function of the treatments studied, under both planting systems.

Fitorremediação de solos contaminados com herbicidas

A fitorremediacao e uma tecnica que objetiva a descontaminacao de solo e agua, utilizando-se como agente de descontaminacao plantas. E uma alternativa aos metodos convencionais de bombeamento e tratamento da agua, ou remocao fisica da camada contaminada de solo, sendo vantajosa principalmente por apresentar potencial para tratamento in situ e ser economicamente viavel. Alem disso, apos extrair o contaminante do solo, a planta armazena-o para tratamento subsequente, quando necessario, ou mesmo metaboliza-o, podendo, em alguns casos, transforma-lo em produtos menos toxicos ou mesmo inocuos. A fitorremediacao pode ser empregada em solos contaminados por substâncias inorgânicas e/ou orgânicas. Resultados promissores de fitorremediacao ja foram obtidos para metais pesados, hidrocarbonetos de petroleo, agrotoxicos, explosivos, solventes clorados e subprodutos toxicos da industria. A fitorremediacao de herbicidas apresenta bons resultados para atrazine, tendo a especie Kochia scoparia revelado potencial rizosferico para fitoestimular a degradacao dessa molecula. Embora ainda incipiente no Brasil, ja existem estudos sobre algumas especies agricolas cultivadas e especies silvestres ou nativas da propria area contaminada, com o objetivo de selecionar especies eficientes na fitorremediacao do solo.Phytoremediation is a technique that uses plants as agents of soil and water decontamination. It is an advantageous alternative to the conventional methods of water pumping and treatment and/or physical removal of the contaminated soil layer since it allows in situ treatment at feasible costs. Also, after extracting the contaminant from the soil, the plant stores it for a subsequent treatment, if necessary, or may metabolically transform it into products that are less or non-toxic. Phytoremediation can be employed in soils contaminated by inorganic or organic substances. Promising phytoremediation results have been obtained in soils contaminated by heavy metals, petroleum hydrocarbons, pesticides, explosives, chlorinated solvents and toxic industrial by-products. Herbicide phytoremediation presents interesting results for atrazine, with Kochia scoparia species revealing rhizospheric potential for phytostimulating molecule degradation. Although this technique is not well known in Brazil, studies have been performed using agricultural crops and wild or native plant species from contaminated areas to select efficient species for soil phytoremediation.

Acúmulo de nutrientes pelo cafeeiro sob interferência de plantas daninhas

Young coffee plants are very sensitive to weed interference due to the high nutrient competition among these plants. This work was conducted to evaluate the interference effects of seven weed species on the relative contents (RC) of macro and micro-nutrients in coffee shoot dry matter. At 30 days after coffee seedling transplantation in 12 L pots, the weeds were transplanted to or sowed in those pots (0, 1, 2, 3, 4 and 5 plants per pot). The weedy periods, from weed transplantation or emergence to plant harvesting, were 77 days - Bidens pilosa, 180 days - Commelina diffusa, 82 days - Leonurus sibiricus, 68 days - Nicandra physaloides, 148 days - Richardia brasiliensis and 133 days - Sida rhombifolia. B. pilosa, C. diffusa, L. sibiricus and R. brasiliensis caused considerable decreases in the nutrient RC of the coffee plants, even at low densities. B. pilosa absorved the highest nutrient amounts, while N. physaloides and S. rhombifolia caused the least interference in coffee plants. The degree of interference depended both on the species and density of the weeds.

Dinâmica populacional de plantas daninhas sob diferentes sistemas de manejo nas culturas de milho e feijão

Com o objetivo de avaliar a dinâmica populacional de plantas daninhas por meio de parâmetros fitossociologicos, realizou-se este trabalho com as culturas de milho e feijao em cultivos sucessivos, no periodo de novembro de 1998 a maio de 2001, em um Argissolo Vermelho-Amarelo Câmbico, fase terraco, em Vicosa-MG. A comunidade de plantas daninhas era composta por Amaranthus deflexus, Brachiaria plantaginea, Cyperus rotundus, Galinsoga parviflora, Mucuna aterrima e Oxalis latifolia. Os tratamentos foram constituidos de dois sistemas de manejo do solo (plantios convencional e direto) e duas finalidades de uso da cultura do milho (grao e silagem), em blocos com quatro repeticoes. No plantio convencional, antes da semeadura das culturas, o solo foi arado e gradeado, e, no plantio direto, foi realizada a dessecacao das plantas daninhas com herbicidas sistemicos. As avaliacoes de plantas daninhas na cultura do milho foram realizadas antes e apos a aplicacao dos herbicidas nicosulfuron e atrazine em pos-emergencia (aos 20 e 55 DAE, respectivamente) no ano agricola 1999/00, e apos a aplicacao de atrazine e metolachlor em pre-emergencia (aos 20 DAE) em 2000/01. Em se tratando do feijoeiro, as avaliacoes tambem foram feitas antes e apos a aplicacao dos herbicidas fluazifop-p-butil e fomesafen, em pos-emergencia aos 20 e 40 DAE, respectivamente. A dinâmica populacional foi avaliada por meio do uso de parâmetros fitossociologicos baseados na densidade, frequencia e biomassa das especies amostradas. Verificou-se aos 20 DAE, antes da aplicacao dos herbicidas em ambas as culturas (milho e feijao), maior densidade e importância relativa das especies dicotiledoneas no plantio direto. No plantio convencional constatou-se maior densidade, dominância e importância relativa de Cyperus rotundus. Apos aplicacao dos herbicidas seletivos, Cyperus rotundus foi a especie de maior importância relativa em todos os sistemas estudados. Em ambas as finalidades de uso do milho, Cyperus rotundus teve sua populacao reduzida no plantio direto, quando comparado com o convencional.

Growth analysis of Digitaria insularis

Digitaria insularis is a perennial species that reproduces from seeds and rhizomes, being difficult to control after its first flowering. In order to define integrated management techniques to this species, its growth was evaluated under greenhouse conditions, using a pot filled with 0.003 m3 of soil. Height, leaf area and dry matter evaluations were carried out between 14 and 112 days after emergence (DAE), every 7 days, at 15 different times. The experiment was arranged in a completely randomized block design, with four replications. The plant was fragmented into root+rhizome, stem and leaf. After drying at 70 oC, leaf area and dry matter were determined. Highest leaf area and dry matter values were verified at 98 and 105 DAE, respectively. Leaves showed higher participation in dry matter total accumulation followed by roots+rhizome, up to 105 DAE. Dry matter accumulation of Digitaria insularis slowed down up to 45 DAE, increasing due to rhizome formation. Relative growth rate values decreased along time due to higher photo assimilate accumulation. Digitaria insularis showed slow growth up to 45 DAE, increasing from 45 to 105 DAE, suggesting the possibility of good cultural control by crops that have fast initial growth and large leaf area, covering the soil rapidly.

Efeitos de sistemas de manejo sobre a população de tiririca

Em experimento conduzido em campo, de novembro de 1998 a maio de 2001, sobre Argissolo Vermelho-Amarelo Câmbico de alta fertilidade, em Vicosa-MG, foram avaliados os efeitos de sistemas de manejo do solo na populacao de tiririca (Cyperus rotundus). Na area experimental, antes da instalacao do experimento predominava infestacao alta (720 ± 130 plantas m-2) de tiririca. Os tratamentos foram constituidos de dois sistemas de manejo do solo (plantios convencional e direto) e duas finalidades de uso da cultura do milho (grao e silagem), cultivados com feijao de outono-inverno em sucessao a cultura do milho, em blocos com quatro repeticoes. No plantio convencional, antes da semeadura das culturas, o solo foi arado e gradeado, e, no plantio direto, foi realizada a dessecacao das plantas daninhas com glyphosate + 2,4-D. As avaliacoes das manifestacoes epigeas da tiririca na cultura do milho ocorreram aos 20 e 55 dias apos a emergencia (DAE) no ano agricola 1999/00 e aos 20 DAE em 2000/01 e, para o feijoeiro, aos 20 e 40 DAE. A avaliacao do banco de tuberculos foi realizada apos a colheita do milho, no ultimo ano de conducao, determinando-se a densidade, a biomassa e a porcentagem de brotacao dos tuberculos coletados. Verificou-se reducao das manifestacoes epigeas da tiririca no sistema de plantio direto em ambas as finalidades de uso da cultura do milho durante todo o periodo de conducao do ensaio. Tanto no milho cultivado para grao quanto para silagem, constatou-se elevada reducao do banco de tuberculos no plantio direto, com predominio de tuberculos dormentes, em relacao ao plantio convencional.

Fitorremediação do herbicida trifloxysulfuron sodium

This work aimed to evaluate the efficiency of plant species in the phytoremediation of the herbicide trifloxysulfuron sodium in soils, by using corn crop as a bioindicator. The treatments were composed by the combination of the species (Calopogonium muconoides, Crotalaria juncea, Crotalaria spectabilis, Vicia sativa, Cajanus cajan, Canavalia ensiformis, Helianthus annus, Dolichus lablab, Pennisetum glaucum, Stylosantes guianensis, Mucuna deeringiana, Mucuna cinereum, Mucuna aterrima, Raphanus sativus and Lupinus albus) sowed before the corn, without previous cultivation (control), and three rates of trifloxysulfuron sodium (0.00,3.75 and 15.00 g ha-1). The experiment was arranged in a randomized block design, in a factorial scheme, with three replicates. Eighty days after sowing, the plants were cut and the shoots discarded. After that, corn (cultivar AG-122) was sowed. Forty five days after emergence, corn height and shoot dry biomass were recorded. M. aterrima and C. ensiformis were considered efficient regarding decontamination of the herbicide residues in soil.

Interferência das plantas daninhas na cultura da soja cultivada em dois espaçamentos entre linhas

O presente trabalho teve como objetivo determinar o periodo anterior a interferencia, o periodo total de prevencao da interferencia e o periodo critico de prevencao da interferencia das plantas daninhas na cultura da soja, cultivar UFV-16, nos espacamentos entre linhas de 30 e 60 cm, mantendo-se uma populacao fixa de 400.000 plantas ha-1 nos dois espacamentos. Os tratamentos foram constituidos de dois grupos: em um manteve-se a cultura na ausencia de plantas daninhas em periodos iniciais apos a emergencia da cultura, e, no outro, a cultura foi mantida na presenca de plantas daninhas em periodos iniciais apos a emergencia da cultura. Os periodos foram os seguintes: 0, 10, 20, 30, 40, 50 e 60 dias apos a emergencia, totalizando 14 tratamentos, dispostos em blocos casualizados, com quatro repeticoes. O periodo critico de prevencao da interferencia na soja, considerando a reducao na produtividade de 2%, localizou-se entre o 7o e 53o dia e o 18o e 47o dia para os espacamentos de 30 e 60 cm entre linhas, respectivamente. Assim, para a soja cultivada em menor espacamento entre linhas (30 cm), o controle das plantas daninhas deve ser iniciado mais cedo, quando comparado com espacamento maior nas entrelinhas (60 cm).

Crescimento do eucalipto sob efeito da deriva de glyphosate

The possible negative effects of glyphosate drift on eucalyptus plants throughout their cycle are one of the many issues faced in forestry. Thus, 120 plants presenting variable degrees of intoxication were randomly selected at day 30 after application of 1.440 g ha-1 glyphosate, aiming to control the weeds in an area of Eucalyptus grandis x E. urophylla (urograndis hybrid) at 120 days after transplantation. The treatments were constituted by the following intervals: 0-5; 6-10; 11-20; 21-30; 31-40 and 41-50% of plant intoxication with 0-5% being considered the control treatment. Height and diameter were evaluated after plant selection, up to 360 days after application (DAA) and the intoxication symptoms were evaluated during this period. At 360 DAA wood volume (m3) was estimated and height and diameter gains were calculated. Plants with initial intoxication above 31% presented lesser height and diameter at 270 DAA Height gains were lesser in plants with initial intoxication above 41%. Lesser diameter was observed from 21% intoxication, with the plants with 41-50% intoxication displaying the lesser values for diameter growth. The damage caused by the drift affected wood production at 270 DAA, with the plants with 21-30, 31-40 and 41-50% intoxication being the ones presenting reduced wood volume of 18, 26 and 48%, respectively, in relation to the control treatment. The results confirmed the damage caused by glyphosate drift to eucalyptus plants. However, new evaluations should be performed to monitor the growth and development of the plants until the end of their cycle so as to elucidate the drift effects on the final production.