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Cressleaf Groundsel (Butterweed) Identification and Management in Pastures

B. A. Sellers, Pratap Devkota, and J. A. Ferrell

The number of calls about a succulent plant with many yellow flowers has increased over the past several years. In certain cases, the infestation has been so severe that the pasture looks like a sea of yellow in April and May. While dealing with row crops, we tend to think of wild radish when we see a sea of yellow flowers. In fact, the plant infesting pastures during the late winter and early spring is commonly known as butterweed or cressleaf groundsel (Packera glabella, formerly known as Senecio glabellus).

Butterweed is a winter annual that starts to emerge as early as November in certain areas of the state. It tends to prefer moist soils, so its presence in low-lying areas in pastures is quite common. It initially grows as a rosette with leaves oppositely arranged on the stem, but it may appear to have whorled leaves because the internode length on the stems tends to be fairly short (Figure 1). Leaves of this plant tend to be deeply lobed, except at the seedling stage, when the leaves are nearly entire (without lobes). As the flowering stalk elongates, the stems become ribbed with red or purple streaks (Figure 2). The leaf arrangement becomes alternate on the succulent and hollow stems. Butterweed is typically not recognizable until it begins producing several bright yellow flowers on its stems. Individual flowers, like many of those in the aster family, have both inner (disk) and outer (ray) flowers (Figure 3). Butterweed will have 5 to 15 outer ray petals, making this species distinct from mustards, which only have 4 petals in a cross-like arrangement. Seeds (achenes) contain a white feathery pappus, or tuft of hair, that aids in wind dispersal and spread of the plant.

Figure 1. Butterweed rosette in a bahiagrass pasture. Rosettes of this size are common between late December and early January, and are often seen when other butterweed plants are already flowering in February.
Figure 1.  Butterweed rosette in a bahiagrass pasture. Rosettes of this size are common between late December and early January, and are often seen when other butterweed plants are already flowering in February.
Credit: B. Sellers, UF/IFAS

 

Figure 2. Representation of butterweed growth. Stems of plants are hollow, commonly grow to three feet, and produce many showy yellow flowers.
Figure 2.  Representation of butterweed growth. Stems of plants are hollow, commonly grow to three feet, and produce many showy yellow flowers.
Credit: B. Sellers, UF/IFAS

 

Figure 3. Butterweed flowers.
Figure 3.  Butterweed flowers.
Credit: B. Sellers, UF/IFAS

Butterweed is toxic to both cattle and horses. It is known to cause liver disease in cattle, producing symptoms such as listlessness, decreased appetite, and photosensitization in extreme cases. Horses frequently appear uncoordinated, become entangled in fences, and awkwardly bump into objects after ingesting the plants. Cattle that consumed 4 to 8% of their body weight in green plant over a few days developed acute liver necrosis and died within 1 to 2 days. Cattle that ingested 0.15% of their body weight (fresh weight) of a species in the same genus as butterweed for a minimum of 20 days resulted in 100% mortality. This equates to a 20-day cumulative dose of 2% of an animal's body weight of dry plants (Knight and Walter 2001). It also appears that this species has been responsible for abortions in cattle, making control of butterweed a necessity.

It is common to see butterweed at all stages of growth in late February to late March. Control of butterweed is successful with 2,4-D during the rosette growth stage. That said, more than one application of 2,4-D may be necessary in certain situations due to its limited residual activity. We have observed excellent control of butterweed with GrazonNext HL at 24 oz/acre or Milestone at 3 to 5 oz/acre during all growth stages.

If you have seen this toxic weed in your pastures, you should scout those pastures every winter. Timely herbicide applications will help prevent poisoning of your cattle and horses. If you have additional questions concerning this species, please contact your local county Extension agent.

Reference

Knight, A. P., and R. G. Walter. 2001. A Guide to Plant Poisoning of Animals in North America. Jackson: Teton New Media.

Publication #SS-AGR-403

Release Date:October 2, 2019

Reviewed At:October 25, 2022

Related Experts

Ferrell, Jason A.

Specialist/SSA/RSA

University of Florida

Sellers, Brent A.

Specialist/SSA/RSA

University of Florida

Devkota, Pratap

University of Florida

  • Critical Issue: Agricultural and Food Systems

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition.

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Fact Sheet

About this Publication

This document is SS-AGR-403, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date April 2016. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.

About the Authors

B. A. Sellers, associate professor, Agronomy Department, UF/IFAS Range Cattle Research and Education Center; Pratap Devkota, assistant professor, UF/IFAS West Florida Research and Education Center; and J. A. Ferrell, associate professor, Agronomy Department; UF/IFAS Extension, Gainesville, FL 32611.

Contacts

  • Brent Sellers