With increased reliance on glyphosate for weed control, weed species composition shifts are likely. Changes in relative abundance could arise from differential tolerance or resistance to, or avoidance of, glyphosate. This study characterized the potential changes in seedbank composition of a mixed population of summer annual weeds due to glyphosate application timing. Seven weeds common in soybean fields in the Midwest were introduced at known densities and treated with glyphosate at several treatment timings. Common lambsquarters, common sunflower, common waterhemp, eastern black nightshade, ivyleaf morningglory, shattercane, and woolly cupgrass were selected to represent a range of emergence patterns and tolerances to glyphosate. Seedling emergence and seed production were monitored. Differences in herbicide tolerance and avoidance, through markedly different weed emergence patterns, were strong contributors to projected changes in weed species composition. Lessened sensitivity to glyphosate allowed some emerged species, such as ivyleaf morningglory, to better survive the herbicide. Late emergence allowed others, such as shattercane and ivyleaf morningglory, to avoid glyphosate applications. Such mechanisms may allow specific species to increase in a continuous glyphosate system.
Email your librarian or administrator to recommend adding this journal to your organisation's collection.
* Views captured on Cambridge Core between 20th January 2017 - 1st May 2017. This data will be updated every 24 hours.