Effect of zone and crops rotation on Ischaemum rugosum and resistance to bispyribac-sodium in Ariari, Colombia

Abstract

-The objectives of this research were to evaluate (1) weed species presented in rice fields in relation to the geographical zone and crop rotation and (2) the resistance level of Ischaemum rugosum to the herbicide bispyribac-sodium. For the first objective, were sampled 79 commercial fields of rice to establish weed density, coverage, and rotation system in the evaluated fields with record of bispyribac-sodium application of at least five years. To reach the second objective, the seeds were collected from plants in commercial fields with different control levels of bispyribac-sodium herbicide. Seeds were germinated in trays under controlled conditions. When plants presented three leaves these were treated with bispyribac-sodium at different doses. Percentages of control and dry weight of plants were evaluated 12 days after treatments (dat). Dominant species in evaluated fields was I. rugosum, with a frequency of 100%, presenting escapes to different chemical commercial treatments. No significant differences were recorded between rotation systems, nevertheless, the most of I. rugosum population was found in the system rice-fallow-rice. The response of applications at different concentrations allows concluding that 65% of samples had resistance at different degrees reported as indexes from 2 to 42 which are related to rotation systems.Keywords: wrinklegrass, rice weeds, resistance index, ISCRU. RESUMO -O objetivo desta pesquisa foi (1) avaliar as espécies de ervas encontradas nos campos de arroz com relação à zona geográfica e à rotação das culturas e (2) o nível de resistência de

Confirmation of Multiple Resistant Chloris radiata Population, Harvested in Colombian Rice Fields

“…Similarly, low control percentages (<20%) were recorded using auxinic herbicides, showing possible multiple resistance with quinclorac; both cases still await verification. In Colombia, there are some reports of resistance to these active ingredients in Murdannia nudiflora, Ischaemum rugosum and E. colona, also in rice fields [25,52,53]. Initially, when bispyribac-sodium was introduced, the control of different weeds was satisfactory, and farmers preferred using this herbicide than other alternatives due to its crop selectivity, low dosage, high efficiency and versatility, which led to more than 90% of the area being treated with this active ingredient [53].…”

“…In Colombia, there are some reports of resistance to these active ingredients in Murdannia nudiflora, Ischaemum rugosum and E. colona, also in rice fields [25,52,53]. Initially, when bispyribac-sodium was introduced, the control of different weeds was satisfactory, and farmers preferred using this herbicide than other alternatives due to its crop selectivity, low dosage, high efficiency and versatility, which led to more than 90% of the area being treated with this active ingredient [53]. Quinclorac, a quinolinecarboxylic acid, has 11 reports of resistance, of which ten are associated with rice cultivation [47], due to its selectivity to cultivation and good control of species of the Echinochloa complex [54].…”

“…For example, in the central rice zone in Colombia, 54% of the area routinely used quinclorac mainly in late postemergence for control of E. colona [25]. Weed management implemented in Colombian rice showed high dependence on chemical control, including the use of quinclorac, propanil, fenoxaprop-ethyl, profoxydim, sulfonylurea and bispyribac-sodium [53].…”