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Publication #SP 37

Wild Radish, Raphanus raphanistrum L.1

David W. Hall, Vernon V. Vandiver, and Jason A. Ferrell2

Classification

Common Name: Wild Radish

Scientific Name: Raphanus raphanistrum L.

Family: Cruciferae (Brassicaceae), Mustard Family

Seedling

The seedlings have kidney-shaped cotyledons with evident veins somewhat impressed into the upper surface (Figure 1). The first leaves have smooth margins when they emerge, but these become lobed with age. The first leaves are also quite hairy.

Figure 1. 

Seedling, Wild Radish, Raphanus raphanistrum L.


[Click thumbnail to enlarge.]

Mature Plant

Wild Radish is a winter annual or annual rising from a tap root (Figure 2). This herbaceous plant can reach 1 m in height. The stems of younger plants have stiff, prickly hairs. The stems become smooth with age. Branching varies from one to several. The hairy leaves are lyre-like (broader at the tip than at the base) with rounded, deeply, irregularly cut lobes. This lobing covers about two-thirds of the blade from the base upwards. Hairs occur on both surfaces. The flowers are yellow to white with purple veins in the petals. All the parts of the flower are in fours. The seed pod is narrow, 2-6 cm long, 3-5 mm wide, and pointed at the tip. The mature, brown pod is jointed with few to several segments. Each 1- or 2-seeded, ribbed segment breaks crosswise from the adjoining segments. The longitudinal ribs are apparent only at maturity. The seeds are 2-3 mm long and have a thin, brown seed coat.

Figure 2. 

Mature plant, Wild Radish, Raphanus raphanistrum L.


[Click thumbnail to enlarge.]

History

The descriptive Greek name of the genus Raphanus means "quickly appearing" and refers to the rapid germination of these plants. Raphanistrum from the same Greek root is an old name once used for this genus.

Habitat

This weed is a native of northern Europe and northern Asia and is found in disturbed areas and cultivated fields over most of the world.

Biology

This plant germinates readily. It is a winter annual, dying at the onset of hot weather, but some plants live for one entire year in Florida.

Separation from Wild Mustard

Wild Radish is often confused with Wild Mustard (Brassica kaber). Wild Mustard does not occur as a weed in crops in Florida. The veins in the upper surface of Wild Mustard cotyledons are not apparent in comparison to the impressed veins of Wild Radish cotyledons. Mature Plants of Wild Mustard only have yellow flowers while flowers of Wild Radish can be yellow, white and rarely lavender. The only sure distinction between mature plants is in the fruits. The fruits of Wild Mustard do not have crosswalls between the segments and they split longitudinally. The fruits of Wild Radish contain crosswalls between the segments and do not split. The segments of Wild Radish decompose with age, releasing the seeds.

Control

One of the most common and cost effective methods of controlling wild radish is through the use of herbicides. Some of the most effective and inexpensive herbicides for wild radish control are growth regulators such as 2,4-D and dicamba (Banvel, Clarity, etc.). These herbicides provide excellent control of wild radish when properly applied. The growth regulating herbicides are generally considered safe on grasses. However, grass crops can be injured if these herbicides are applied incorrectly, or at the wrong developmental stage of the crop. Applications of phenoxy-type herbicides should be made to grain crops after two to three tillers have formed; plants are often 4 to 6 inches tall at this time. Applications of these materials before this stage of growth cause a "rat-tail" effect, whereby the leaf does not form and unfurl properly. In addition, the plant may appear stunted and delayed in maturity. Conversely, applications made after the jointing may result in malformed seedheads. Tolerance of cool season forages to herbicides will vary according to species. Generally, wheat is the most tolerant and oats are least tolerant to 2,4-D applications.

The timing of an herbicide application is critical for effective wild radish control. Research has shown that >90% wild radish control can be consistently achieved when 2,4-D is applied to plants less than 6 inches in height. By delaying the application until the plant reaches 12 inches, control drops to approximately 70%. However, if wild radish begins to flower before 2,4-D is applied, less than 50% control should be expected. Therefore, herbicides should be applied early to achieve the greatest wild radish control while avoiding herbicide injury to winter forage.

Footnotes

1.

This document is SP 37, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 1991. Revised February 2006. Reviewed January 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

David W. Hall, former extension botanist, Herbarium, Florida Museum of Natural History; Vernon V. Vandiver, associate professor emeritus, Agronomy Department; Jason A. Ferrell, assistant professor, Agronomy Department; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611.

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 does not signify our approval to the exclusion of other products of suitable composition.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.