DES MOINES, Iowa — The American Seed Trade Assoc. (ASTA) hosted a meeting of grower groups, seed companies and state government officials to discuss a collaborative approach to addressing Palmer amaranth and other weed seed issues.

 

Held May 9 in Des Moines, the meeting served as a productive information-exchange and strategic dialogue about potential short- and long-term solutions, said Andrew LaVigne, president and CEO of ASTA, headquartered in Alexandria, Va.

“Weeds like Palmer amaranth move through many different routes, so controlling them requires an active, unified strategy, including growers, industry and government,” he said.

LaVigne said the meeting raised awareness about the importance of state seed regulatory systems. When it comes to purchasing seed, he said participants underscored the need to communicate with growers the importance of buying professionally-produced seed from a company licensed to do business in the state – and specifically checking if seed was tested both for performance and the presence of Palmer and other weeds.

“The meeting brought together key stakeholders to discuss lessons learned, and strategies for collaboration moving forward as we deal with Palmer amaranth and other new and emerging weed seed issues,” he added.

According to Bob Hartzler, Iowa State University professor of agronomy and extension weed specialist, contamination of conservation seed mixes with the seed of Palmer has resulted in the spread of the aggressively invasive weed from just five of Iowa’s 99 counties at the beginning of 2016, to 49 at the end of the year.

Clarke McGrath, ISU agronomist and on-farm research and extension coordinator at ISU’s Iowa Soybean Research Center in Harlan, said the center is on the lookout for Palmer. “In fact, a lot of us have already been out scouting for Palmer in Conservation Reserve Program (CRP) seedings that we either know or suspect to have Palmer in them,” he said. “It’s critical that we find and control as much Palmer as possible.

“The weed is aggressive enough to really explode if we don’t put in a lot of effort to limit seed production this year – well, more accurately, every year from here forward.”

McGrath’s team suspect that by the end of the 2017 growing season, Palmer could be in about every county in Iowa. “While we are way past concerned, we don’t need to panic yet. From what I saw down South, we can save that stage for a few years from now if we don’t do a good enough job limiting seed production this year.

“Hopefully, it won’t reach that, since we have some advantages in the Midwest now that they didn’t have down South as Palmer started taking over,” he added. Currently, he said the center is scrambling to get some guidance and latitude in controlling Palmer in the CRP. In late April, Gov. Terry Branstad signed a bill adding it to Iowa’s noxious weed law, effective July 1.

“It is important to note that the law requires landowners to get the approval of the Farm Service Agency (FSA) before implementing control strategies in CRP,” McGrath said. “While that will dictate to some degree how we deal with Palmer, there may be some flexibility in which of the approved tactics can be used or combined.

“It sounds like that while mowing, hand-roguing and spot treatments are the preferred practices, landowners with documented Palmer amaranth infestations will be provided the option of applying broadcast herbicide treatments.”

But before making broadcast applications, McGrath said landowners must certify the contracted area has at least 100 Palmer plants present, “so scouting and accurate weed ID will be on the ‘to do’ list for a lot of us.”

Hartzler said the goal for managing Palmer in CRP fields should be eradication. “It is unlikely a single herbicide application will provide complete control of Palmer amaranth, thus follow-up measures will be essential to eliminating surviving plants and preventing seed production,” he said.

“Spot treatments with an appropriate post-emergence herbicide or hand-roguing  are the preferred options for eliminating plants surviving initial herbicide treatments.”

McGrath said the basic concepts used to fight waterhemp also apply to Palmer  “We have to adapt them to account for some of the competitive advantages Palmer has over waterhemp. But from 2013 through 2016, we had several growers successfully managing Palmer in some of the initial crop fields where it was found.

“Those examples, plus lessons learned from Southern growers, along with some of the newer weed management systems, are now available,” he added. “All of that makes me think that while Palmer is here to stay, we can successfully manage it.”