Offered Papers Theme A: Efficient Production from Grassland
Description
Sulfonylurea (SU) herbicides such as triasulfuron, chlorsulfuron and metsulfuron-methyl are used extensively in the cereal-livestock zones of temperate Australia. They are regarded by farmers as effective, cheap and safe-to-apply herbicides with useful levels of residual activity in the year of application. However these residues can persist into following years, particularly in areas with alkaline soils and low rainfall, where their breakdown by microbial action and chemical hydrolysis is significantly reduced. Regenerating pasture legumes typically used in Australian ley farming systems are highly intolerant of even very low residues of SU herbicides (e.g. < 1ppb; Heap, 2000) resulting in severe stunting, reduced dry matter production, lower seed yields, poor persistence and decreased N fixation. In this study we compare the field performance of an artificially induced mutant cultivar (FEH-1) of annual strand medic (Medicago littoralis) with putative tolerance to sulfonylurea herbicide residues (Heap, 2000) with the cultivar Herald, its intolerant strand medic parent.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Field Performance of an Annual Medic Tolerant of Sulfonylurea Herbicide Residues
Sulfonylurea (SU) herbicides such as triasulfuron, chlorsulfuron and metsulfuron-methyl are used extensively in the cereal-livestock zones of temperate Australia. They are regarded by farmers as effective, cheap and safe-to-apply herbicides with useful levels of residual activity in the year of application. However these residues can persist into following years, particularly in areas with alkaline soils and low rainfall, where their breakdown by microbial action and chemical hydrolysis is significantly reduced. Regenerating pasture legumes typically used in Australian ley farming systems are highly intolerant of even very low residues of SU herbicides (e.g. < 1ppb; Heap, 2000) resulting in severe stunting, reduced dry matter production, lower seed yields, poor persistence and decreased N fixation. In this study we compare the field performance of an artificially induced mutant cultivar (FEH-1) of annual strand medic (Medicago littoralis) with putative tolerance to sulfonylurea herbicide residues (Heap, 2000) with the cultivar Herald, its intolerant strand medic parent.
