Abstract Background Goosegrass is one of the most troublesome weed species in Brazil due to its wide dispersion and the ability to evolve herbicide resistance. Objective Investigate the response of goosegrass accessions from Mato Grosso, Brazil to glyphosate, clethodim, and haloxyfop. Methods Goosegrass seed samples were collected from seventeen production fields (accessions) in Mato Grosso and screened with the recommended label rates of clethodim, haloxyfop-methyl, and glyphosate. Six accessions withstood the label rate of the evaluated herbicides and were subjected to a dose-response study. Out of the six accessions, two were selected for further F1 dose-response investigations due to their ability to survive the label rate of the three herbicides individually. All studies were conducted under greenhouse conditions in a completely randomized design with four replications, and the F1 dose-response study was replicated in time. Results All six accessions investigated in the dose-response study presented ED50 values higher than susceptible plants for control and biomass reduction. Haloxyfop-methyl had the highest resistance ratios, followed by clethodim and glyphosate. The two accessions investigated in the F1 dose-response study were confirmed to be cross-resistant to clethodim and haloxyfop-methyl and showed low-level resistance to glyphosate. Conclusions The continuous reliance of POST herbicides for weed management in Mato Grosso cropping systems has selected goosegrass accessions that can withstand high rates of ACCase-inhibiting herbicides, particularly haloxyfop-methyl. Moreover, two accessions with resistance to ACCase-inhibiting herbicides, clethodim and haloxyfop-methyl, and low-level resistance to glyphosate were identified, suggesting the presence of multiple resistance in goosegrass accessions from Mato Grosso, Brazil.

RESUMO Objetivou-se, nesta pesquisa, avaliar o efeito do uso do herbicida saflufenacil como dessecante em pré-colheita e do armazenamento sobre a qualidade fisiológica e sanitária de sementes de feijão-azuki. Foram testadas seis doses do herbicida saflufenacil (0, 50, 75, 100, 150 e 200 g a.i. ha-1) e duas épocas de avaliação da qualidade das sementes: colheita e seis meses após a colheita. A aplicação do dessecante ocorreu na maturidade fisiológica do feijoeiro azuki e as sementes colhidas foram armazenadas em sacos de papel (Kraft) em ambiente natural, a 25,4 ± 3 ºC de temperatura e 67,3 ± 3% umidade relativa. O saflufenacil pode ser utilizado até a dose de 65 g a.i. ha-1 sem prejudicar a qualidade fisiológica das sementes. O armazenamento provocou queda na percentagem de germinação, aumento no número de plântulas anormais e redução no tamanho e da massa seca das plântulas. A dessecação em pré-colheita e o armazenamento reduzem a infestação Cladosporium, Fusarium, e Rizhopus nas sementes de feijão-azuki.

ABSTRACT The objective of this study was to evaluate the effect of using the herbicide saflufenacil desiccant pre-harvest and storage on the physiological and sanitary quality of azuki bean seeds. Six doses of saflufenacil herbicide (0, 50, 75, 100, 150 and 200 g a.i. ha-1) were tested and two evaluation periods of seed quality: harvest and six months after harvest. The desiccant application occurred at physiological maturity of azuki bean and seeds were stored in paper bags (kraft) under natural conditions - 25.4 ± 3 °C temperature and 67.3 ± 3% relative humidity. The saflufenacil may be used up to a dose of 65 g a.i. ha-1, without harming the physiological seed quality. The storage caused a drop in the percentage of germination, increase in the number of abnormal seedlings and reduction in size and dry mass of seedlings. Desiccation pre-harvest and storage reduces the infestation of Cladosporium, Fusarium and Rizhopus on the azuki bean seed.