Palmer amaranth, a new weed to Iowa and a serious threat to production agriculture, has now been discovered in at least 48 counties in the state. Farmers, farmer advisers and others interested in learning how to identify and manage this new threat are encouraged to attend an upcoming workshop, "Keep Palmer Amaranth off Your Farm." These workshops will be held at several eastern Iowa locations, says Meaghan Anderson, field agronomist with Iowa State University Extension.

Palmer amaranth is an aggressive competitor and prolific seed producer. Careful identification is necessary to manage this new threat, due to its similarity to the common Iowa weed waterhemp.

“With Palmer amaranth discoveries quickly increasing across the state, proper identification is key to controlling infestations and preventing movement to crop fields," Anderson says. "With early identification, eradication of this problem weed is still possible in many areas."

According to Anderson, farmers and field scouts should be observing high-risk areas for Palmer amaranth. These include areas with significant equipment movement, suspicious-looking waterhemp infestations, newly seeded conservation plantings and areas near animal agriculture operations.

Workshop topics will include Palmer amaranth identification, and management in crop fields and in Conservation Reserve Program (CRP) areas. There also will be a discussion of common questions and concerns regarding Palmer amaranth.

There is no cost to attend these workshops. However, those interested in attending a workshop should preregister by contacting the ISU Extension and Outreach county office at the phone numbers below. A two-hour workshop will be held at the following locations:

• Feb. 27, 11:30 a.m., with a light meal; ISU Extension Jones County office, 800 N Maple St. #2, Monticello; preregister by calling 319-465-3224
• March 1, 6:30 p.m., with refreshments; Heartland Acres Agribition Center, 2600 Swan Lake Blvd., Independence; preregister by calling 319-334-7161
• March 2, 6:30 p.m., with a light meal; ISU Extension Washington County office, 2223 250th St., Washington; preregister by calling 319-653-4811
• March 20, 6 p.m., with a light meal; Traer Public Library, 531 Second St., Traer; preregister by calling 641-484-2703
• March 21, 6 p.m., with a light meal; ISU Extension Iowa County office, 223 West Welsh St., Williamsburg; preregister by calling 319-668-1052
• March 30, 6:30 p.m., with refreshments; ISU Extension Johnson County office, 3109 Old Highway 218 South, Iowa City; preregister by calling 319-337-2145

CCA credits are available
The workshop qualifies for certified crop adviser credits. Credits have been applied for. Sign-up sheets will be available on the day of the workshop. For further information, please contact Meaghan Anderson at 319-337-2145 or [email protected].

In 36 counties last year, Palmer amaranth was found on conservation plantings such as CRP land, buffer strips, etc., and the source of the weed seed is believed to have been forage seed that was contaminated with Palmer seed. Control options on conservation acres are limited, although farmers and ISU Extension weed management specialists are hopeful that USDA conservation agencies will provide some leniency and allow farmers to slow the spread of Palmer amaranth on their farms.

Currently, the two primary options for control on conservation acres are mowing and removal by hand. But there are drawbacks with those methods. The weed likely spread too many seeds last year to make hand roguing a viable option in most cases. And Palmer seeds can survive mowing and will continue to spread viable seeds after regrowth. The big concern is, if all you can do is mow, then that Palmer amaranth is going to produce so much seed that it’s going to escape those conservation areas and get into corn and soybean fields.

The keys to minimizing Palmer’s impact on long-term crop yields are early detection and rapid response in managing this weed. There are major cost savings in eradicating a weed species from a field, rather than letting it go and thinking you’ll control it later. With Palmer you have to take a zero-threshold approach; be determined that you’re not going to let this weed survive in your field.

Source: Iowa State University