The phytotoxic effect of ALS inhibiting herbicide combinations in prairie soils

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.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Plant Sciences

Grantor

University of Saskatchewan

Year dc:date.issued

2007

Author dc:creator

• Geisel, Bryce G. L.

Advisors dc:contributor.advisor

• Schoenau, Jeffrey J. (Jeff)
• Holm, F. A. (Rick)

Committee members dc:contributor.committeemember

• Shirtliffe, Steven J.
• Johnson, E. N.
• Coulman, Bruce E.

• environmental conditions
• recrop injury
• soil properties
• herbicide persistence
• root inhibition bioassay
• oriental mustard
• dose response models

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/10388/etd-03292007-100002

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/etd-03292007-100002