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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.

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. 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 Tuiuiú) e dez populações de picão-preto para cada cultivar. Avaliaram-se as variáveis população de plantas, área foliar, cobertura de solo e massa seca da parte aérea de picão-preto como indicador de infestação. A massa seca da parte aérea do picão-preto apresentou melhor ajuste ao modelo da hipérbole retangular, e as perdas de produtividade de grãos, devido à interferência do picão-preto, podem ser estimadas satisfatoriamente por esse modelo. Os cultivares BRS Esplendor e a IPR Tuiuiú foram os mais competitivos do que os demais na presença do picão-preto. A semeadura dos cultivares BRS Esplendor, IPR Tuiuiú e Fepagro 26 aumentou o nível de dano econômico, justificando a adoção de medidas de controle do picão-preto em densidades mais elevadas. Incremento na produtividade de grãos, no preço do feijão e na eficiência do herbicida e redução no custo de controle diminuem os valores do nível de dano econômico, o que justifica a adoção de medidas de controle em baixas densidades de picão-preto.