-This study aimed to understand the influence of sowing depth and the amount of sugarcane straw on the emergence of weed species Luffa aegyptiaca Miller (Cucurbitaceae); Mucuna aterrima Piper & Tracy (Fabaceae -Leguminosae) and Ricinus communis (Euphorbiaceae). A completely randomized design with a 5 x 4 x 3 factorial layout with four replications was used, at five sowing depths (0, 2, 4, 8 and 10 cm), four different amounts of sugarcane straw (0, 5, 10 and 15 t ha -1 ) and three different evaluation periods (7, 14 and 21 days after sowing). After sowing, different amounts of sugarcane straw (0, 5, 10 and 15 t ha -1 ) were deposited on soil. Seedling emergence was analyzed at 7, 14 and 21 days after sowing, counting the number of seedlings that had emerged. At the end of the trial, weed height (cm), leaf area (cm 2 ) and shoot dry mass (g) were measured. In relation to emergence ability, studied species presented different responses according to sowing depth and to the amount of sugarcane straw deposited on the soil. For the L. aegyptiaca and M. aterrima, no significant difference was observed in the interaction between depth and sugarcane straw, showing the adaptation of these species to no-burn sugarcane system. For R. communis, seeds placed at 0 cm of sugar cane straw depth were observed to favor the emergence of seedlings.Keywords: germination, no-burn sugarcane, mechanized harvesting. RESUMO

The emergence of resistant biotypes of the Amaranthus palmeri species in cotton production areas of the state of Mato Grosso, Brazil, generated the need for correct identification of this species and information on viable herbicidal tools for their management. Thus, greenhouse experiments were conducted to evaluate the efficacy of alternative herbicides applied to A. palmeri in pre and post emergence. A randomized block design with four replications was used. The efficacy of herbicides applied in pre emergence was evaluate in two experiments, one in a clayey and other in a sandy soil; 9 herbicide treatments (8 with herbicide application and a control without application) were applied on each soil. Subsequently, two experiments with different populations of A. palmeri were conducted, using a 13 x 2 factorial arrangement, to evaluate the efficacy of herbicides applied in post emergence. The factors consisted of 13 herbicide treatments (12 with herbicide application and a control without application) and two weed development stages (2-4 and 6-8 leaves). Pre-emergence application of the flumioxazin, S-metolachlor, isoxaflutole, and trifluralin herbicides controlled the weed satisfactorily in both evaluated soils. The sulfentrazone and metribuzin herbicides were effective in the sandy soil, and diuron was effective in the clayey soil. The clomazone herbicide did not successfully controlled the A. palmeri plants in any of the soils. All post-emergence herbicide treatments were effective for the management of A. palmeri plants, when they were applied at the 2-4 leaf stage.

Resumo -A alta frequência de Merremia aegyptia nos canaviais colhidos de forma mecânica está relacionada à sua adaptação a esse sistema de colheita, o que resultou em um aumento do potencial de infestação dessa espécie em relação a outras plantas daninhas. O objetivo deste trabalho foi avaliar o manejo de M. aegyptia pela aplicação de herbicidas em pré-emergência na presença e ausência de palha em solo argiloso submetido a diferentes lâminas de água. Dois experimentos foram realizados no delineamento inteiramente casualizado, com quatro repetições. Em cada experimento foi avaliado uma mistura de herbicida: mesotrione + atrazine (0,25 + 3,0 L i.a. ha -1 ) e diuron + hexazinone + sulfometuron-methyl (1386 + 391 + 33,35 g i. ha -1 ). Os tratamentos foram arranjados em esquema fatorial 8 x 2 x 2, sendo oito profundidades avaliadas (0, 5, 10, 15, 20, 25, 30 e 35 cm), duas coberturas (com e sem palha) e duas lâminas de agua após a aplicação dos herbicidas (20 e 40 mm). Os herbicidas foram aplicados sobre colunas preenchidas com solo de textura argilosa com 0 e com 10 t ha -1 de palha sobre a superfície dos canos e que posteriormente foram colocadas em simulador de chuva. Após a irrigação, as colunas foram abertas longitudinalmente e mantidas em casa-de-vegetação por 72 horas. A semeadura da M. aegyptia (planta alvo) foi feita em espaços de 5 cm no centro de cada parte da coluna. A associação mesotrione + atrazine apresentou controle em maior profundidade de M. aegyptia com 40 mm de precipitação (23 cm) no tratamento com ausência de palha. O diuron + hexazinone + sulfometuron-methyl apresentou controle até próximo a 15 cm de profundidade em ambas simulações de chuva e a palha apresentou pouca interferência na ação da mistura. Palavras-chaves: corda-de-viola, controle químico, lixiviação, percolação Abstract -The high frequency of M. aegyptia in sugarcane harvested mechanically is related to its adapting behavior to this harvesting system, what resulted in an increased the infestation potential of this species in relation to other weeds. The aim of this study was to evaluate the management M. aegyptia by spraying pre-emergence herbicides, in the presence and absence of straw in clay soil, under different rainfall simulation. Two experiments were carried out in a completely randomized design with four replications. In each experiment was evaluated the 1 Recebido para publicação em 12/11/2014 e aceito em 15/07/2015.

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência AbstractThe objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla ('capim-branco') and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha -1 ) were assessed on the emergence of Indian goosegrass and 'capim-branco' in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha -1 ) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The 'capim-branco' showed a marked reduction in emergence beginning at 2 t ha -1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha -1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha -1 ), whereas no emergence of the 'capimbranco' was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha -1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used. We concluded that the increase in the sowing depth and the amount of straw significantly reduced the emergence of the species and that the presence of straw and the dry period interfered with the herbicide efficacy. Key words: Indian goosegrass. 'Capim-branco'. Sugarcane. Straw. ResumoObjetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram real...

A cana-de-açúcar tem grande importância econômica no Brasil. Para manter sua produtividade diversos fatores bióticos e abióticos podem influenciar positiva ou negativamente. Dentre eles, podem ser citados as plantas daninhas, os nematoides e a interação entre produtos fitossanitários para o controle de ambos. Em função disto, o presente trabalho teve como objetivo estudar a interação entre herbicidas e nematicidas usados na cultura da cana-de-açúcar. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 3, com 4 repetições. O primeiro fator corresponde aos herbicidas sulfentrazone (800 g ha-1 a.i.), saflufenacil (98 g ha-1 a.i.), diuron + hexazinone (1170 g ha-1 a.i. + 330 g ha-1 a.i.), amicarbazone (1050 g ha-1 a.i.), mais a testemunha; o segundo fator aos nematicidas benfuracarbe (2000 g ha-1 a.i.), carbofuran (1750 g ha-1 a.i.), mais a testemunha. Os nematicidas foram aplicados em contato com os toletes e os herbicidas aplicados em pré-emergência da cultura, sendo realizado nas variedades de cana-de-açúcar RB867515, RB975201 e RB975952. As avaliações de fitotoxicidade foram realizadas aos 7, 15, 30, 45 e 60 dias após a emergência (DAE) da cultura. Na última avaliação foram determinados os parâmetros biométricos altura, área foliar e biomassa seca da parte aérea. Todas as plantas se recuperaram aos 60 DAE, sendo que nos tratamentos com o uso do herbicida sulfentrazone foram observados sintomas mais elevados de intoxicação. Quanto aos parâmetros biométricos avaliados aos 60 DAE, não houve interação significativa para os fatores herbicida e nematicida, mas houve diferença entre os tratamentos em cada variedade.

Annual crops and crotalaria intercropping has been used to control nematodes. The evaluation of the susceptibility of crotalaria species to herbicides is an important step to make this technology viable. The aim of this experiment was to determine the tolerance of Crotalaria juncea, C. ochroleuca, C. spectabilis and C. breviflora to pre and post-emergence herbicides. Post-emergence (bentazon, ametryn, amicarbazone, 2,4-D amine and mesotrione) and pre-emergence herbicides (atrazine + mesotrione, atrazine + simazine, atrazine, isoxaflutole, pendimenthalin, s-metolachlor and trifluralin) were evaluated in doses of 0.5D; 0.75D; 1D and 1,25D; in which D was the commercial dose of each product. The results demonstrated that the species of crotalaria differ on the susceptibility to pre and post emergence herbicides. Among the post-emergence herbicides, bentazon showed higher selectivity. However, reduced doses of some post-emergence herbicides can make the intercropping with some species of crotalaria viable. The most selective pre-emergence herbicides were pendimenthalin, s-metolachlor and trifluralin. In general, C. spectabilis was the most susceptible to the evaluated herbicides.

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The coffee plant is sensitive to weed competition, which negatively affects its growth and development. Thus, the proper and safe use of herbicides is extremely important for weed management to allow the crop to develop its maximum productive potential. The objective of this study was to evaluate the control efficacy of different herbicides under pre-emergence conditions and assess their selectivity for coffee crops. Two experiments were carried out in the field, in randomized block designs, with four replicates and eight treatments, totaling 32 experimental plots. The treatments were: unweeded control; weeded control; sulfentrazone + diuron 1.4 L ha -1 ; sulfentrazone + diuron 1.7 L ha -1 ; sulfentrazone + diuron 2.0 L ha -1 ; sulfentrazone + diuron with indaziflam 1.4 + 0.15 L ha -1 ; respectively, indaziflam 0.15 L ha -1 ; and oxyfluorfen + chlorimuron 3.0 L ha -1 + 0.08 kg ha -1 , respectively. The treatments were applied prior to the emergence of weeds in a directed spray between the crop rows. Evaluations of weed control in the area, phytotoxicity to the crop, branch length, and internode distance of coffee were conducted at 30, 60, 90, and 120 days after treatment application (DAA). In general, all treatments guaranteed greater than 80% efficacy up to 60 DAA. After this, some treatments suffered reductions in efficacy, and did not guarantee satisfactory control up to 120 DAA. For Digitaria nuda, the most effective treatments were those that contained indaziflam alone or in combination with sulfentrazone + diuron, and oxyfluorfen + chlorimuron for 60 DAA. In both experiments and the two species analyzed, the indaziflam treatments guaranteed efficacy percentages above 80%, even at 120 DAA. All treatments were equally selective for the coffee plants under the conditions evaluated.