Farmers urged to report Palmer amaranth sightings
The Minnesota Soybean Research and Promotion Council is advising farmers to keep their eyes open in their fields this fall for Palmer amaranth, a fast-growing weed that can dramatically decrease soybean yields.
Palmer amaranth is a weed native to the southwestern region of the United States, as well as northwestern Mexico. It has spread east and north and has developed a resistance to multiple classes of herbicides and their various action modes, making it very difficult and expensive to control.
“It’s a serious weed in most of the southeastern United States row crop areas,” David Kee, Director of Research for the Minnesota Soybean Research and Promotion Council, told the Mascot last week.
“It has made steady progress northward, surviving in multiple areas of Iowa. It is a warm season annual, and appears to germinate after April in Minnesota. We do not know if Palmer seed can survive the winters in Minnesota.”
Palmer amaranth was discovered in Lyon County two years ago, but since the Minnesota Department of Agriculture began eradicating efforts, it has not been seen in that location this fall. It was also located in Douglas, Todd and Yellow Medicine Counties two years ago, and more recently was located in Redwood and Jackson counties in Minnesota.
The Minnesota Soybean Research and Promotion Council is advising farmers to promptly report any findings.
“Interesting enough, in Minnesota, reported Palmer amaranth discovery has only been by farmers, not by MDA, Extension or Industry,” said Kee.
“The first thing to do is contact your local agronomic advisors, crop consultants, or Extension educators to access the situation and develop a plan of attack.” “Control efforts will vary depending on the situation and crop dependent.
Make sure MDA is aware as they can provide resources to assist with control.”
To date, it has not been documented as to the extent of damage the Palmer amaranth weed has caused. “There are too few sties of impact in our region to estimate crop damage,” Kee said.
“It is a major problem in the southern United States soybean production areas with the potential 70 percent reduction in soybean yield documented.”
Kee noted that as long as the weed remains green due to high moisture status and is resistant to many common harvest aid (desiccation herbicide) products, it is famous for delaying harvest and increasing harvest difficulty.
Palmer amaranth is a prolific seed producer. As many as 50,000 seeds can come from one plant. It has a growth rate of two to three inches per day and commonly reaches heights of six to eight feet, which can greatly inhibit crop growth.
The weed can also increase production costs for farmers who grow soybean, corn and other crops. Reported yield losses have been up to 91 percent in corn and 79 percent in soybean in some states.
The spread of the weed has been linked to several areas. “To date, most of the reports has been associated with CRP or Pheasants Forever conservation plantings using out-of-state sourced seed,” Kee noted.
“The recent discoveries in row crop fields have been linked to many-caused events such as purchased manures from out of state and used equipment.”
“The academic, commodity, industrial and regulatory (UMN and MDA) communities will be including an increased sanitation message to the farmer in the upcoming months.”
Beginning in 2014, Palmer amaranth has been listed on Minnesota’s Prohibited Noxious Weed Eradicate List. All above and below ground parts of the plant must be destroyed in order to completely eliminate it.
How to identify Palmer amaranth:
•They generally can grow to 6-8 feet, but can reach as high as 10 feet tall.
•The green leaves are smooth and arranged in an alternate pattern that grows symmetrically around the stem. The leaves are oval or triangular shaped.
•The leaves of some Palmer amaranth plants include a light-colored V-shaped mark on them, although not all display this characteristic.
•Look similar to native pigweeds such as tall Waterhemp, Powell’s amaranth, and redroot and smooth pigweeds.