This year at the Iowa State University Field Extension Education Lab (FEEL), ISU Extension weed management specialist Bob Hartzler has a special project in the weed garden at that training site. The FEEL Lab is located at the ISU agronomy research farm, just west of Ames. In the weed garden, Hartzler has established a “weed identification” plot with nine weedy members of the Amaranth family, including six pigweeds.

These weeds are all “cousins” — so to speak. If you are going to develop a management plan and choose a herbicide program to try to control them, you need to know for sure which cousin is the problem weed in your field.

Think you know your pigweeds?
On the ISU Integrated Crop Management website, Hartzler has created the Weedy Amaranthus Quiz II. Readers are encouraged to take the quiz to see if they really know their pigweeds.

The six weedy Amaranthus species Hartzler has growing at the weed garden have grown quite a bit since he first posted this quiz and photos online a couple weeks ago. That was June 14. He showed the weeds as a topic in his blog on the ISU ICM website. Today is June 26, and those weeds are bigger now — as shown in the “Weedy Amaranthus Quiz II.”

Take this online weed identification test
Hartzler encourages you to take this online test. The six pigweeds are Palmer amaranth, Powell’s amaranth and spiny amaranth, waterhemp, redroot pigweed and tumble pigweed. But they are not listed in that order in the photos in his quiz!

“The purpose of the quiz is to demonstrate how easy it would be to overlook Palmer amaranth in fields if you don’t take the time to make sure exactly what Amaranthus you are dealing with,” says Hartzler. View the six members of the pigweed family Hartzler has listed in his quiz. They are identified in the photos as Amaranthus 1 through 6, with the answers at the bottom.