Nick Fetty | January 8, 2015

Palmer amaranth, waterhemp, and other nuisance plant species continue to be growing problems for farmers in Iowa and neighboring states.

Weather and environmental conditions are two factors that have contributed to this problem. Droughts in 2013 forced farmers to delay application of herbicides and cool, wet conditions in 2014 further exacerbated the situation with problem weeds.

Waterhemp is “one of the most common weeds with which Midwest farmers must contend” according to data from the Purdue University Extension. Mike Owen – an Iowa State University Extension weed specialist – estimates that 85 percent of Iowa soy bean fields have waterhemp resistance.

In addition to waterhemp, Palmer amaranth has also caused issues for Iowa farmers. Instances of this bothersome weed have been reported in Page, Fremont and Harrison counties in the southwest part of the state in addition to Lee and Muscatine counties in the southeast. Owen said there are likely more unreported cases of Palmer amaranth in Iowa since it is prevalent in nearby states such as Illinois, Kansas, Missouri, and Nebraska.

Robert Hartzler – an Iowa State University Extension weed management specialist – does not believe that Palmer amaranth will be as devastating in Iowa as it has been in southern states. These weeds were largely unheard of prior to the 1980s when weed management practices changed.

Waterhemp and Palmer amaranth are similar in appearance and can often be difficult to differentiate.