The aim of this study was to compare control of three stages biotypes (rosette, bolting, and repro- ductive stage) of Conyza bonariensis glyphosate susceptible biotype (S) and tolerant biotype (T) to glyphosate with g...The aim of this study was to compare control of three stages biotypes (rosette, bolting, and repro- ductive stage) of Conyza bonariensis glyphosate susceptible biotype (S) and tolerant biotype (T) to glyphosate with glyphosate and mixtures of acetolactate synthase (ALS)-inhibiting. For glyphosate, the dose-response curves confirmed that injury of the biotype T relative to biotype S was signifi- cantly lower for both rosette and bolting stages. Resistance index (RI) for this herbicide was approximately 4 for both weed stages. At bolting, for both biotypes doses much higher than the recommended dose were required. For acetolactate synthase (ALS)-inhibiting herbicides, at the rosette stage, control of both biotypes was excellent with doses significantly lower than the recommended rate. All herbicides within this group showed a very low I50 relative to the recommended rate. These results indicate that biotypes difficult to control with glyphosate at the rosette and bolting stage may be controlled using acetolacte synthase (ALS)-inhibiting herbicides. Control for the reproductive stage was poor. A management program based on the combination of glyphosate with pre- and post-emergence acetolactate synthase (ALS) herbicides may be effective to control the weed.展开更多
A comparative survey of the weed species present in field plots and edges was performed in fields at Zavalla (Santa Fe) Argentina in the soybean central region of the country in order to determine changes in cover, fr...A comparative survey of the weed species present in field plots and edges was performed in fields at Zavalla (Santa Fe) Argentina in the soybean central region of the country in order to determine changes in cover, frequency and diversity of the weed communities. Five to twelve soybean fields were surveyed in 2006, 2007, and 2009. Weed surveys were carried out in the soybean fallow in winter and after soybean planting in spring. In edges, species richness was higher than in field plots in spring-summer but diversity showed an erratic response. The weed community cover showed a shift in weed vegetation composition relative to the field plot. Our results indicate that the community in crop edges relative to field plots differs in structure and abundance and that many weed species are only present either in crop edges or in field plots.展开更多
文摘The aim of this study was to compare control of three stages biotypes (rosette, bolting, and repro- ductive stage) of Conyza bonariensis glyphosate susceptible biotype (S) and tolerant biotype (T) to glyphosate with glyphosate and mixtures of acetolactate synthase (ALS)-inhibiting. For glyphosate, the dose-response curves confirmed that injury of the biotype T relative to biotype S was signifi- cantly lower for both rosette and bolting stages. Resistance index (RI) for this herbicide was approximately 4 for both weed stages. At bolting, for both biotypes doses much higher than the recommended dose were required. For acetolactate synthase (ALS)-inhibiting herbicides, at the rosette stage, control of both biotypes was excellent with doses significantly lower than the recommended rate. All herbicides within this group showed a very low I50 relative to the recommended rate. These results indicate that biotypes difficult to control with glyphosate at the rosette and bolting stage may be controlled using acetolacte synthase (ALS)-inhibiting herbicides. Control for the reproductive stage was poor. A management program based on the combination of glyphosate with pre- and post-emergence acetolactate synthase (ALS) herbicides may be effective to control the weed.
文摘A comparative survey of the weed species present in field plots and edges was performed in fields at Zavalla (Santa Fe) Argentina in the soybean central region of the country in order to determine changes in cover, frequency and diversity of the weed communities. Five to twelve soybean fields were surveyed in 2006, 2007, and 2009. Weed surveys were carried out in the soybean fallow in winter and after soybean planting in spring. In edges, species richness was higher than in field plots in spring-summer but diversity showed an erratic response. The weed community cover showed a shift in weed vegetation composition relative to the field plot. Our results indicate that the community in crop edges relative to field plots differs in structure and abundance and that many weed species are only present either in crop edges or in field plots.
