The phytotoxic effect of ALS inhibiting herbicide combinations in prairie soils

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Date
2007-03-30Author
Geisel, Bryce G. L.
Type
ThesisDegree Level
MastersMetadata
Show full item recordAbstract
The objective of this study was to determine if the presence of two ALS inhibiting herbicide residues in three Saskatchewan soils would result in an additive, synergistic, or antagonistic interaction. This was determined through field trials where herbicides were applied sequentially over the course of two years and through dose-response modelling. The herbicides examined in these experiments were imazamethabenz, flucarbazone-sodium, sulfosulfuron, and florasulam, each in combination with imazamox/imazethapyr. The phytotoxicity and persistence of the herbicides in soil was assessed using an Oriental mustard root inhibition bioassay. The determination of herbicide interaction was made through the comparison of the experimentally observed values to theoretically expected values derived from a mathematical equation.The dose response curves created by placing incremental concentrations of these herbicides in soil were compared using the I50 parameter, which is the concentration resulting in a 50% reduction in root length. It appeared that soil organic matter followed by soil pH had the greatest effect in reducing herbicide residue phytotoxicity in the tested soils. Based on the bioassay analysis of sequentially applied ALS inhibiting herbicides, it is proposed that the phytotoxic effect of herbicide residues in soil result in additive injury effects rather than synergistic or antagonistic interactions.
Degree
Master of Science (M.Sc.)Department
Plant SciencesProgram
Plant SciencesSupervisor
Schoenau, Jeffrey J. (Jeff); Holm, F. A. (Rick)Committee
Shirtliffe, Steven J.; Johnson, E. N.; Coulman, Bruce E.Copyright Date
March 2007Subject
environmental conditions
recrop injury
soil properties
herbicide persistence
root inhibition bioassay
oriental mustard
dose response models