By Willy Klein
Weeds are the most prevalent pest complex negatively impacting Iowa agriculture. This status has earned weeds an invitation to the Iowa State University Tent at the 2018 Farm Progress Show.
“Weed management issues were very evident in 2017, and we have them again this year,” says Bob Hartzler, agronomy professor and Extension weed specialist at ISU. “Palmer amaranth populations have been identified in new Iowa counties and, eventually, will likely be identified in every Iowa county. Weed populations with evolved resistances to herbicides continue to escalate statewide.”
Several common Iowa weeds have evolved resistance, such as waterhemp, horseweed and giant ragweed. All of the weeds in Iowa with evolved resistance to herbicides are annuals and are well adapted to current production agriculture systems. Once established in a weed population, the resistance remains.
Controlling resistant weeds
Hartzler and a team of ISU Extension field agronomists will be at the ISU Tent during FPS with several common weeds and demonstrations showing how different herbicide groups work and explaining which groups work on different weeds at different stages of growth.
“Weed management remains a major concern for Iowa agriculture, and addressing these burgeoning problems requires greater diversity of tactics beyond herbicides,” Hartzler says.
Accurate weed identification is the first step to successfully managing weeds, making field scouting important to a well-designed plan. Because weed species vary in their response to different management strategies, proper identification is vital.
Hartzler and Meaghan Anderson, ISU Extension field agronomist, plan to challenge FPS visitors’ weed identification skills.
KNOW YOUR WEEDS: In addition to the Iowa State Fair weed contest Meaghan Anderson and Bob Hartzler conduct each year, they are bringing weed identification to the Farm Progress Show this summer.
An effective weed management plan also protects crops from weed competition, prevents weed populations from increasing over time, minimizes herbicide injury and delays, or prevents herbicide-resistant weed development.
“These plans must include cultural, mechanical or chemical control methods that are specific to the particular cropping system and weeds present,” Anderson says.
Klein is a communication specialist with ISU Extension and Outreach.