Marestail, also known as horseweed or Canada fleabane, is a winter or summer annual weed in Nebraska. Historically, marestail was found in waste area, field edges, along roadsides, and railway tracks; however, no-till crop production systems over the last 20 years favor marestail germination and establishment in agronomic crops in Nebraska.
Management of glyphosate-resistant weeds is now the greatest challenge for Nebraska crop producers and land managers. The 2017 Herbicide Classification Chart from Take Action Against Weeds is an easy means for identifying herbicide site of action to avoid repeated use of the same action on the same field.
A new soybean cultivar with dicamba-tolerant Roundup Ready 2 Xtend™ soybean is expected to be planted on over 15 million acres in 2017, offering an additional means of managing herbicide-resistant weeds. The weed management system, which was tested the last four years in Nebraska trials, provides for use of Roundup Xtend™ of XtendiMax™ (dicamba).
In Nebraska, eight weed species (common ragweed, common waterhemp, giant ragweed, kochia, marestail, Palmer amaranth, redroot pigweed, and shattercane) have been confirmed resistant to at least one herbicide. Six of them — common ragweed, common waterhemp, giant ragweed, kochia, marestail, and Palmer amaranth — have been confirmed resistant to glyphosate in Nebraska. This article reviews information presented at the Weed Management Field Day at the UNL South Central Ag Lab, focusing on field demonstrations and methods to reduce the development of further herbicide resistance.