Cleber Daniel de Goes Maciel

Resistência de amendoim - bravo aos herbicidas inibidores da enzima ALS

One of the most efficient methods of weed control in agriculture is the use of selective herbicides. However, repetitive use of the same herbicide or herbicides having the same mechanism of action, has led to the appearance of weed biotypes which have developed resistance. Thus, an experiment was carried out at Embrapa Soja, in Londrina, Parana State, Brazil, in order to confirm whether or not there has been resistance of the weed E. heterophylla to the ALS inhibitor herbicides which had been sprayed for several years in a soybean field where the grower has observed failure of the weed control by the ALS inhibitor herbicides. The suspected resistant plants (E-298) from Cafelândia county, Parana, Brazil, were treated with various doses of several herbicides, compared to a known susceptible biotype. The herbicides and its doses were cloransulan 0,0; 0,015; 0,03; 0,06; 0,12; 0,24 kg a.i./ha, plus Agral 0,2% v/v, imazetaphapyr 0,0; 0,05; 0,1; 0,2; 0,4 e 0,8 kg a.i./ha, imazaquin 0,0; 0,075; 0,15; 0,3; 0,6; 1,2 kg a.i./ha, plus Assist 0,3% v/v, sulfentrazone 0,0; 0,3; 0,6; 1,2; 2,4; 4,8 kg a.i./ha, plus Assist 0,3% v/v and lactofen 0,0; 0,082; 0,165; 0,33; 0,664; 1,329 kg a.i./ha.The results indicated different patterns of cross resistance to cloransulan, imazethapyr and imazaquin; and the GR50 ratios were 97.74; 11.90 and 10.86, respectively. The dose response curves of the resistant biotype presented lower values than the susceptible biotype in all the studied rates for the herbicides cloransulan, imazethapyr and imazaquin. On the other hand, there was no difference in the control between the resistant and susceptible biotypes when sulfentrazone and lactofen were sprayed. It was observed efficient control, mainly with the highest rates of both herbicides, proving that there is no multiple herbicide resistance of the wild poinsettia studied.

Efeito de herbicidas sobre quatro espécies de trapoeraba

Chemical weed control of Commelina species (wandering-jew) is sometimes unsatisfactory. This work was carried out to observe the effect of herbicides on Commelina species at post-emergence. C. benghalensis, C. villosa, C. diffusa and C. erecta were treated with carfentrazone-ethyl (30 g ha-1 and 50 g ha-1), glyphosate (960 g ha-1), carfentrazone-ethyl plus glyphosate (30 + 960 g ha-1), sulfentrazone plus glyphosate (150 + 960 g ha-1), and a control, when the plants displayed 15 to 25 cm long stems. The experimental design was completely randomized with four replications. Commelina chemical control was different among species. Best control was achieved with C. benghalensis and C. erecta had the worst level of control. The treatment with carfentrazone-ethyl plus glyphosate showed the best results on the control of these four Commelina species, compared to other applications.

Composição florística da comunidade infestante em gramados de Paspalum notatum no município de Assis, SP

Os gramados de Paspalum notatum sao os mais disseminados no Brasil, constituindo diferentes locais e propositos. A infestacao por plantas daninhas acarreta perda de qualidade estetica quando a finalidade do gramado e ornamental. Com o objetivo de caracterizar a comunidade infestante em gramados de P. notatum no municipio de Assis/SP, foi realizado entre os meses de junho e julho de 2004 um levantamento floristico em areas ensolaradas e sombreadas, sob copas de arvores. Cem amostras de 0,50 x 0,50 m foram coletadas nas duas condicoes de luminosidade (50 em areas ensolaradas e 50 em areas sombreadas), a partir das quais foram calculados os parâmetros frequencia, densidade, abundância, frequencia relativa, densidade relativa, abundância relativa e indice de valor de importância. Ao todo, foram identificadas 45 especies de plantas daninhas, distribuidas em 15 familias; Asteraceae apresentou o maior numero de especies nas condicoes ensolaradas e sombreadas. As especies mais importantes nas areas ensolaradas foram: Oxalis latifolia > Desmodium incanum > Cyperus flavus > Cyperus diffusus > Cyperus brevifolius; e nas areas sombreadas: C. brevifolius > Alternanthera tenella > D. incanum > Elephantopus mollis > C. flavus. Para 80,0% das amostragens, a massa seca total da parte aerea das especies de plantas daninhas nao sofreu influencia das condicoes ensolarada ou sombreada, constituindo uma producao maxima de aproximadamente 150 kg ha-1 para ambas as condicoes.

selectivity of soybean RR® genotypes submitted to glyphosate + chlorimuron-ethyl tank mixtures associated to mineral oil and insecticides

The use of glyphosate for weed control in soybean RR® presents essential practical characteristics. However, although not allowed by the current Brazilian legislation, the association with other herbicides has been increasing for species of difficult control, as well as the use of tank mixtures combined with insecticides and adjuvants. Aiming to evaluate the selectivity of soybean RR® genotypes submitted to tank mixtures of the glyphosate formulations (Polaris®, Roundup Ready® and Roundup WG®) with chlorimuron-ethyl (Classic®), and their associations with mineral oil (Joint Oil®) and novaluron insecticides (Gallaxy 100 EC®), permethrin (Piredan®) and methomyl (Lannate BR®), an experiment was conducted under field conditions at Maracai -Sao Paulo, during the 2006/2007 growing year. The experiment was arranged in a randomized complete block design with four replications, in a factorial scheme 16 x 4, with 16 representing the tank mixture associations of glyphosate formulations, mineral oil and insecticide, and the four genotypes Monsoy 7210RR®, Monsoy 7979RR®, BRS245RR® and CD 214RR®. Visual symptoms of initial intoxication in the genotypes studied were characterized by chlorosis and wrinkle in the leaves for all tank mixtures of glyphosate + chlorimuron-ethyl, associated or not with mineral oil, and novaluron, permethrin and methomyl insecticides .None of the tank mixtures promoted significant yield reductions for Monsoy 7210RR®, Monsoy 7979RR® and BRS245RR® genotypes, and controlled Ipomoea spp with satisfactory effectiveness, starting from 21 DAA (days after application).

Misturas em tanque com glyphosate para o controle de trapoeraba, erva-de-touro e capim-carrapicho em soja RR ®

Although the use of glyphosate tank mixtures for managing weed species of difficult control is prohibited by theBrazilian legislation, it has been a common practice among farmers. This work aimed to evaluate the efficiency andselectivity of herbicide tank mixtures using glyphosate to control Commelina benghalensis L., Tridax pr ocumbens L.and Cenchr us echinatus L. in soybean crop RR

Desenvolvimento de gramados submetidos à aplicação de retardadores de crescimento em diferentes condições de luminosidade

In order to evaluate the development of the grass species Bermuda (Cynodon dactylon), Emerald (Zoysia japonica) and Broadleaf Carpetgrass (Axonopus compressus) submitted to herbicide sub doses and growth regulators under two light conditions, three experiments were conducted in a greenhouse at Paraguacu Paulista from September to December, 2006. For each grass species, the experimental design used was completely randomized, in a factorial scheme 6 x 2, with four replications, using two growth regulators (trinexapac-ethyl and ethephon), three herbicides applied in sub doses (clethodim, imazethapyr and metsulfuron-methyl), and a check without application. All treatments were evaluated under two light conditions, represented by plastic greenhouse (total light) and plastic greenhouse + shading 50% (partial light).The results obtained at 63 days after application showed that trinexapac-ethyl (250 g ha-1), clethodim (12 g ha-1) and imazethapyr (12 g ha-1) were the best growth regulators for the vegetative development of C. dactylon (65.8, 29.6 and 18.7%), Z. japonica (66.2, 40.7 and 49.7%) and A. compressus (56.5, 10.3 and 17.2%) grasses and for inflorescence emission of C. dactylon (100.0, 95.9 and 89.6%), under high and low luminosity. Ethephon (300 g ha 1) and metsulfuron-methyl (3.6 g ha-1) treatments were found to be the best options for reducing vegetative development (15.5 and 26.7%) and root dry matter (34.7 and 33.9%) of Sao Carlos grass (A. compressus), compared to trinexapac-ethyl. For C. dactylon and Z. japonica turf grass, under conditions where aesthetics preservation is fundamental, clethodim and imazethapyr may substitute trinexapac-ethyl growth regulator on account of the smaller visual damage in the grass. Further studies with growth regulators and herbicide sub doses must be conducted with other cultivated grasses to enable efficient and safe recommendations, based on scientific information generated from Brazilian conditions.

Seletividade e eficácia de herbicidas inibidores da enzima accase na cultura da mamona

Universidade Estadual de Maringa (UEM) CCA UEM, Dep Ciencias Agron, BR-87507190 Umuarama, PR, Brazil

Levantamento fitossociológico de plantas daninhas em cafezal orgânico

A adequacao de um cafezal para o sistema orgânico causa grande mudanca no sistema de manejo de plantas daninhas, mas as informacoes sobre o comportamento da comunidade infestante em areas de cultivo de cafe orgânico sao escassas no Brasil. Objetivou-se com este trabalho realizar um levantamento fitossociologico da comunidade infestante em tres cafezais (variedades Mundo Novo, Bourbon Vermelho e Obata) desenvolvidos em sistema orgânico, no municipio de Garca (SP). Nas tres areas estudadas foram arremessados ao acaso cem quadrados metalicos com area vazada de 0,25 m2, nas entrelinhas da cultura. As especies contidas no interior dos quadros foram identificadas segundo a especie botânica, nome popular e familia. A partir dos resultados, determinaram-se os parâmetros fitossociologicos: frequencia, densidade, abundância, frequencia relativa, densidade relativa, abundância relativa, indice de valor de importância e similaridade floristicas pelos metodos de Simple Matching de Sneath & Sokal e similaridade de Sorensen. As familias que mais se destacaram, com maior numero de especies nas tres areas foram Poaceae e Asteraceae. Houve alta similaridade em todos os contrastes testados, ja que pelo menos metade das especies identificadas foi comum as duas areas contrastadas.

Desempenho de pontas de pulverização em Brachiaria brizantha cv. MG-4 para controle de ninfas de cigarrinhas das pastagens

Escola Superior de Agronomia de Paraguacu Paulista Departamento de Ciencias Biologicas e Fitossanitarias

Interferência de plantas daninhas no cultivo da melancia

Water melon crop is an agricultural activity explored regionally, representing one of the most important sources of family income in small cities of the Medio Paranapanema, Sao Paulo State, Brazil, where nowadays, significant changes in the yield process are verified, changing from intensive labor to the use of promising technologies, as weed management, for instance. An experiment was carried out at Oscar Bressane municipal district, Sao Paulo State, Brazil, to study the weed interference on watermelon cultivation, in 2002/2003. Statistical procedure was based on randomized blocks with ten treatments and four replications, represented by plots with useful area of 18 m2, containing four water melon plants and infestation of Sidaspp, Brachiaria humidicola, Commelina benghalensisand Portulaca oleraceaspecies. Weed infestation was estimated through randomized samples from the plots, using an iron drained square with 0,5 m sides. Treatments consisted of checks with and without hand weeded and different periods of weeds control, so that, crop was sustained in weeds presence or absence up to 7; 14; 28; 56 and 63 days after emergency (DAE). Initial period occurrence of possible coexistence greater than the final period established the Critical Period of Interference Prevention from the 9th to the 13th days (CPIP = 9-13 DAE). The reduction in yield due to the weed interference during all water melon crop cycle was about 41,4%. The diameter and thickness of fruits peel were also influenced by the coexistence with weed infestation during all the crop cycle, with decreases of 7,9% and 23,3%, respectively, against the characteristics length and diameter of branch and oBrix of fruits pulp, when significant differences were not observed.