Objetivou-se com o trabalho determinar a habilidade competitiva de cultivares de soja na presença de picão-preto e leiteiro, em diferentes proporções de plantas na associação. O experimento foi conduzido em delineamento experimental de blocos casualizado, com quatro repetições. Os competidores testados incluíram o picão-preto e o leiteiro com cultivares de soja, nas proporções de 30:0; 20:10; 15:15; 10:20 e 0:30 plantas vaso-1 cultura: planta daninha. Aos 50 dias após a emergência da cultura e/ou das plantas daninhas foram avaliadas as variáveis área foliar (AF) e massa seca da parte aérea (MS). Ocorreu competição entre as cultivares de soja na presença de picão-preto e/ou leiteiro, sendo afetados negativamente, independentemente da proporção de plantas, provocando em todos os casos redução na AF e da MS das espécies. A soja apresentou maior competividade que o picão-preto e/ou o leiteiro. O leiteiro apresenta maior agressividade que o picão-preto ao ocasionar menor produção de AF e MS das cultivares de soja. A competição interespecífica causa maiores prejuízos a AF e a MS das espécies do que a intraespecífica. Ocorre basicamente a competição pelos mesmos recursos do meio entre a cultura da soja com as plantas daninhas picão-preto e o leiteiro.

RESUMOObjetivou-se com o trabalho avaliar os efeitos de épocas de emergência das plantas daninhas, azevém e nabo, sobre a cultura da cevada. O experimento fo i conduzido em delineamento de blocos casualizados, arranjado em esquema fatorial 2x5, com três repetições. No fator A, foram alocadas as plantas competidoras (azevém e nabo) e no B as épocas de emergência (14 e 07 dias antes, no mesmo dia, 07 e 14 dias depois da emergência da cultura). No inicio da floração da cevada, foram mensuradas as variáveis: estatura das plantas, número de colmos ou caules, área foliar e matéria seca da parte aérea da cultura e das plantas daninhas. Todas as variáveis avaliadas da cevada apresentaram aumento de valor com o atraso da emergência das plantas daninhas. As espécies, cultivada ou daninhas, que emergiram antes, apresentaram maior habilidade competitiva, dominando o ambiente quando emergiram 14 dias antes uma da outra. Quanto mais tarde ocorrer a emergência das plantas daninhas com relação à cultura, menor é a interferência e, desse modo, maior é a habilidade da cevada em competir com a espécie daninha pelos recursos disponíveis no meio. Palavras-chave: Hordeum vulgare, Lolium muUiflorum, Raphanus raphanistrum. ABSTRACT The objective was to evaluate the effects o f times o f emergence o f the weed ryegrass species and wild radish on barley. The experiment was conducted in a randomized block design, arranged in a 2x5 factorial design, with three replicates. In factor A were allocated the competing species (ryegrass and wild radish) and in factor B the emergence periods (14 and 7 days before, on the same day, 7 and 14 days after crop emergence). At the beginning o f barley flowering, the following variables were quantified: plant height, number o f stalks or stems, leaf area, and shoot dry mass o f crop and weeds. All barley variables had increased in value with the delay in weed emergence. The species, cultivated or weeds, that emerged earlier showed greater competitive ability, dominating the environment when emerging 14 days before each other. The later the emergence o f weeds with respect to the crop, the less the interference they cause, and, thereby, the crop presents a greater ability to compete with the weeds for available resources in the environment.

-The aim of the study was to assess the interference and determine the economic threshold level of beggartick damage on bean crops. Treatments consisted of bean cultivars (IPR Uirapuru, BRS Supremo, BRS Campeiro, Fepagro 26, BRS Esplendor and IPR Tuiuiú) submitted to competition with ten beggartick populations. We evaluated plant population, leaf area, ground cover and shoot dry mass of beggartick. Dry mass of shoots of beggartick fitted better to the hyperbolic model, and grain yield losses due to beggartick interference were estimated satisfactorily by this model. BRS Esplendor and IPR Tuiuiú were more competitive than the others in the presence of beggartick. Sowing of BRS Esplendor, IPR Tuiuiú and Fepagro 26 increases the level of economic damage, justifying the adoption of control measures only for higher densities of beggartick. Increase in grain yield, commercial price of beans, herbicide efficiency and reduction in control cost decrease the threshold level for weed control, justifying application of control measures for lower densities of beggartick. Keywords: Phaseolus vulgaris, Bidens pilosa, interference. RESUMO -Objetivou-se com este trabalho avaliar a interferência e determinar o nível de dano econômico de picão-preto infestante da cultura do feijão. Os tratamentos foram compostos por cultivares de feijão (IPR Uirapuru, BRS Supremo, BRS Campeiro, Fepagro 26, BRS Esplendor e IPR

The results allowed concluding that the management methods of weed ryegrass must be adopted in the period between 11 and 21 days after crop emergence, which is described as a critical period of control of this weed. The wheat grain yield loss competing with ryegrass reached 59% when grown with ryegrass. For ETL, the linear regression model of the rectangular hyperbola adequately estimates grain yield losses in the presence of ryegrass. The cultivar presenting the lowest values of ETL, that is, less capacity to live with the weed, was TBIO Alvorada. The other cultivars presented similar ETL values.

Corn stands out among the cultivars because of its high importance in food, animal feed and raw materials for energy production. The quantity and quality of the harvested grain can be reduced, mainly due to inadequate weed management. Nowadays, weed control is accomplished with the use of herbicides as pre-emergence and postemergence, applied alone or in a tank mix. This study aimed to evaluate the efficiency of the control of weeds and phytotoxicity of the herbicides that were applied in tank mix or isolated in the corn hybrids, Formula TL ® and SYN 7B28. Two experiments were conducted: in the 2012/2013 season (Formula TL ® ) and 2013/2014 season (SYN 7B28). There was a low initial phytotoxicity of all the tested herbicides in the initial evaluation; however, from 14 days after treatment, it was minimal. The weed control of Ipomoea indivisa, Urochloa plantaginea and Euphorbia heterophylla in both experiments was better, in general, when using the tank mixtures of atrazine + simazine + tembotrione and atrazine + simazine + mesotrione, respectively. The application of atrazine + simazine + tembotrione in the SYN 7B28 hybrids provided, with the exception of the thousand-grain weight, the best expression of grain yield components, combining a low phytotoxicity and best control of the weeds. The Formula TL ® hybrid presented the highest mass of a thousand grains and yield with the application of nicosulfuron + tembotrione. The yield average difference of the herbicide treatments and the unweeded control showed an increase of 27.66 and 34.59% in the grain yield of the corn hybrids, Formula TL ® and SYN 7B28, respectively. Aureo, methylated soybean oil; MOAH, mineral oil aromatic hydrocarbon; MSO, methylated seed oil. 28L. Galon et al.

Identifying the competitive ability of corn hybrids and the economic injury level (EIL) caused by Urochloa plantaginea is important for the adoption of integrated management of this weed. This work aims to evaluate the interference and EIL of U. plantaginea infesting corn hybrids. Treatments included the corn hybrids Syngenta Status VIP3, Syngenta SX8394 VIP3, Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021, as well as 12 densities of U. plantaginea for each hybrid. We used a rectangular hyperbolic model to describe the relationship between corn grain productivity loss and the explanatory variables — plant density (PD), dry mass (DM) of the aerial parts, ground cover (GC), and leaf area (LA). EIL was determined using grain productivity, control cost, corn price, and herbicide efficacy. The rectangular hyperbolic model provides a satisfactory estimate of grain productivity loss regarding the interference of U. plantaginea in corn culture. The hybrids Pioneer 30F53 YH and Pioneer P1630H presented better competitiveness and higher EIL. Sowing the hybrids Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021 increased EIL, justifying the adoption of control measures for U. plantaginea at higher densities.

The lack of registered herbicides for weed control in sweet sorghum has been a limiting production factor. This study aimed at evaluating the selectivity of herbicides in sweet sorghum and weed control efficiency. A randomized blocks design, with four replications, was used. Treatments consisted of sweet sorghum cultivars (BRS 506, BRS 509 and BRS 511) and herbicides applied alone at pre-emergence (atrazine - 1,500 g ha-1; atrazine + s-metolachlor - 1,665 g ha-1 + 1,035 g ha-1; flumioxazin - 50 g ha-1; s-metolachlor - 1,440 g ha-1) and post-emergence (tembotrione - 100.8 g ha-1) and sequentially at pre- and post-emergence (atrazine + s-metolachlor + tembotrione - 1,665 g ha-1 + 1,035 g ha-1 + 100.8 g ha-1; atrazine + tembotrione - 1,500 g ha-1 + 100.8 g ha-1; flumioxazin + tembotrione - 50 g ha-1 + 100.8 g ha-1), plus two controls, one weeded and one unweeded. The phytotoxicity rate to sorghum was 98.0 %, 98.0 % and 100 % for tembotrione; 100 %, 98.7% and 100 % for flumioxazin + tembotrione; 100 %, 100 % and 100 % for s-metolachlor + atrazine + tembotrione; and 98.7 %, 98.7 % and 99.7 % for atrazine + tembotrione, respectively to the BRS 509, BRS 506 and BRS 511 cultivars. Tembotrione, flumioxazin + tembotrione, atrazine + s-metolachlor + tembotrione and atrazine + tembotrione showed a good control rate of Ipomoea indivisa, Digitaria ciliaris and Urochloa plantaginea, but did not present selectivity to the sorghum cultivars. Atrazine, in general, showed higher selectivity to the yield components of the BRS 509 and BRS 506 cultivars.

The prospection of bioherbicides has been an alternative to weed control, aiming at mitigating chemical risks to human, animal and environmental health due to extreme use of synthetic herbicides. In the present study, various fungi were isolated from plants with symptoms of fungal diseases for bioherbicide purposes against weeds ( Urochloa plantaginea , Euphorbia heterophylla and Bidens pilosa ). Fungi isolated were identified by molecular methods and enzymatic products obtained by fungi fermentation (cellulase, lipase, peroxidase, and amylase) were quantified. Bioherbicide selectivity study was performed on crops (soybean and corn), as well as on resistant weeds. Among the isolated fungi, Fusarium oxysporum , Fusarium ploriferatum, and Trichoderma koningiopsis presented bioherbicide potential. T. koningiopsis , in particular, presented the highest effect on Euphorbia heterophylla (popular name - Mexican fire plant), causing up to 60% of foliar damage, without presenting phytotoxicity against corn crop. New perspectives for weeds control and their use in corn crops were prospected, considering the bioherbicide selectivity described in this study.