Have You Seen This Weed Called Cressleaf Groundsel?

Stan Smith, PA Fairfield County OSU Extension


Some are asking how to kill it. Others want to know how to propagate it. Most are wondering what it is.

In recent years, groundsel – cressleaf which is a bi-annual and ragwort which is a very similar perennial – have become an increasing problem in minimum and no-till row crop fields and also aging hay fields with less than acceptable stands. This year due to the very early spring weather where many bi-annual and perennial plants got started two weeks or more ahead of normal, we’ve seen more throughout Ohio than perhaps ever before. Of significance to livestock producers is the fact that cressleaf groundsel is currently included in Ohio’s Noxious Weed List due to its poisonous characteristics.

OSU Extension beef and sheep veterinarian Dr. Bill Shulaw tells us that under typical grazing conditions in Ohio, it is unlikely that animals will consume significant quantities of groundsel because of the availability of higher quality, more palatable forages. However, Shulaw says poisoning could result under unusual conditions, such as drought, where good quality forage is not available. Hay containing significant amounts of the plant may pose an even greater risk according to Shulaw.

Poisoning usually occurs as a result of consumption of the plants over several days to several months. Because the effect on the liver is cumulative, signs of poisoning can occur weeks to months after consumption of the plant ceases. The signs are directly attributable to liver degeneration and failure. Affected animals usually show depression and loss of appetite initially, and progress to neurological signs with head pressing, aimless walking, incoordination, and rectal straining.

In the OSU publication Cressleaf Groundsel the plant is described as a member of the Aster/Composite family. It goes by many other names, including butterweed, yellowtop, golden ragwort, and yellow ragwort. It has a winter annual life cycle, meaning that it emerges in the fall and flowers in the spring. Cressleaf groundsel reproduces only from seeds. Each plant produces many (probably 100’s of thousands) seeds that are readily moved by wind currents. It grows well in many different environments including saturated soils.

Nearly all species of groundsel are considered potentially toxic plants because they contain compounds called pyrrolizidine alkaloids (PAs). These are metabolized in the liver to other compounds that are toxic, primarily to the liver cells. The PAs are found in the plant throughout the growing season but appear to be at their highest levels when the plant is in the bud to flower stage. The flowering portions of the plant and the youngest tissues generally contain the highest concentrations. PAs are not destroyed by the hay-making and curing process. Ensiling of forages may reduce the concentration of PAs, but will not entirely eliminate them. Sheep are considered more resistant to the effects of PAs than cattle and horses, and have been used in some areas to control the plant. However, sheep are susceptible to poisoning if they consume sufficient amounts.

For more information on identifying cressleaf groundsel, see OSU Bulletin 866 at this link: http://ohioline.osu.edu/b866/b866_12.html

For more information on management and control of the plant, go to this PDF version of the publication Cressleaf Groundsel: http://agnr.osu.edu/sites/agnr/files/imce/pdfs/Beef/Cressleaf.pdf