Agriculture Reference
In-Depth Information
Chapter 2
D ETECTION OF S OIL -A PPLIED H ERBICIDES
BY S UGAR B EET P LANTS
Anna M. Szmigielski and Jeff J. Schoenau
Soil Science Department, University of Saskatchewan,
Saskatoon, Canada
A BSTRACT
Sugar beet ( Beta vulgaris L.) is an effective bioindicator plant used for bioassay
detection of herbicide residues in soil because of its sensitivity to many herbicides. In
bioassays the response of a bioindicator plant to a herbicide is measured, and once the
response in a designated herbicide concentration range is established, the bioassay can be
used in research and soil testing. Typically research focuses on assessment of the effect
of soil properties on herbicide bioactivity and dissipation in soil, while soil testing is
carried out to identify the potential for injury to rotational crops due to residual herbicides
that may persist in soil to the next growing season.
Application of the sugar beet bioassay for assessment of how herbicide behavior in
soil is influenced by soil properties was investigated using two herbicides that have
different modes of action i.e., pyroxsulam and pyroxasulfone. Pyroxsulam is a Group 2
(acetolactate synthase inhibitor) herbicide that primarily inhibits root length of sensitive
plants, while pyroxasulfone is a Group 15 (long chain fatty acid elongase inhibitor)
herbicide that generally affects shoot growth of susceptible plants.
This chapter describes (1) the sugar beet bioassay technique for detection of
pyroxsulam and pyroxasulfone in soil, and (2) the use of this bioassay for evaluation of
pyroxsulam and pyroxasulfone bioactivity and dissipation in soil.
I NTRODUCTION
Sugar beet is susceptible to many herbicides that are commonly used in various crops.
Consequently, the conventional weed control in sugar beet production is difficult as herbicide
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