PPDL Picture of the Week

March 13, 2017

Cressleaf Groundsel

Travis Legleiter, Weed Science Program Specialist, Purdue University

As the spring progresses, you will start to notice that fields will start turning fairly pretty colors such as bright purple and yellow.   It is most likely you will see this in no-till fields especially in southern Indiana.  The weed that are responsible for turning fields bright yellow is cressleaf groundsel, which is also referred to as ragwort and butterweed.

This yellow flowering weed is often confused with the mustard family because of its deeply lobed leaves and yellow flowers.  Upon closer inspection it is much different than the mustards though and have several distinguishing characteristics.  Cressleaf groundsel is a winter annual that emerges in the fall as a rosette and has the distinct deeply lobed leaves, in the spring the plant bolts on a hollow stem, and produces the bright yellow ray flowers.  The characteristics that set cressleaf groundsel apart from the mustards include the hollow stem and the ray flowers.  The mustards will have a solid stem, will have four petal yellow flowers, and have the distinctive silique seedpods that cressleaf groundsel lacks.

While cressleaf groundsel typically does not compete directly with crops, as it is usually gone by late spring due to its winter annual growth cycle, it can delay crop planting.  As with many winter annuals, the dense populations of plants in field keep the soil from drying and warming up causing a delay in planting.  The most effective method of control is to apply a burndown in the fall when plants are small.  A burndown can also be applied in the spring, although at this point the weeds have already produced seed that will contribute to future generations.