Wild radish (Raphanus raphanistrum)
Wild radish dominating a crop of canola
(Photo A. Storrie)
Wild radish (Raphanus raphanistrum) is generally a winter and spring growing annual which may grow up to 1.5 m high. The cotyledons are heart-shaped and hairless with long stems. The first true leaves are irregularly lobed around the edges with one or more completely separated lobes at the base of the leaf blade.
The seedling develops into a flat rosette, the leaves of which do not have a distinct stalk. Erect branches covered with prickly hairs arise from near the base as the plant matures. The rosette of lobed leaves does not persist.
Lower stem leaves are covered with prickly hairs and deeply lobed, with a rounded terminal lobe. When crushed these leaves have a strong turnip-like odour. Upper stem leaves become narrower, shorter and often undivided.
Flowers are in clusters on the ends of stem branches. They have four petals which alternate with four sepals. The petals may vary in colour; yellow or white petals are more common than purple, pink or brown. Petals often have light or dark distinct veins.
The seed pod is constricted between the seeds and does not split lengthwise. It breaks up into distinct segments when ripe, and during threshing it is often broken up into single-seeded segments. Each pod usually has three to nine seeds, ovoid to almost globular, yellowish to reddish brown, and covered with white bran-like scales. There is no seed in the beak of the pod.
Factors that make Wild radish a major weed:
- The ease of dissemination has resulted in its widespread occurrence
- Very competitive because of the rapid establishment of its seedlings and the relatively fast growth rate
- Lupin, wheat, field pea and barley grains rapidly lose their viability during storage when contaminated with green wild radish pods
- The fibrous stems can make harvesting difficult by choking the header comb
- Moisture levels of harvested grain can be affected
- Can cause animal health problems
- Has allelopathic activity
- Is an alternate host for a number of pests and diseases
- Produces abundant seeds
- Complex seed dormancy is one of the most important characteristics that enables wild radish to persist as a weed of cropping
- Can germinate at any time of the year given sufficient soil moisture
- The flexible flowering patterns of wild radish, requiring less than 600 degree-days to flower, indicate that wild radish has the capacity to grow and set seeds in most areas of southern Australia
- Seed persistence is greatest when seed is buried at depths greater than 40 mm
- Sheds pods before crop harvest, enabling it to persist in cropping systems
- Through its genetic and phenotypic variability, wild radish has managed to adapt well to varied crops, environments and control tactics
- Being an outcrossing species, wild radish has sufficient genetic variability and biochemical adaptability to evolve resistance to the commonly used herbicides in cropping systems
Further detail about this weed including integrated weed management tactics that could be considered when developing a management plan can be found in the section on problem weeds in the Integrated Weed Management Manual.
Ecology and biology of common weeds are outlined in section 6 of the Integrated Weed Management Manual.
Wild radish management and strategies to address herbicide resistance (2014)
Hand weeding of wild radish sometimes cheaper than spraying (2016)
Controlling stacked resistant radish with herbicides WA (2014)
Spray resistant radish early for best efficacy and yield WA (2014)
Managing wild radish (Raphanus raphinistrum) in grain crops - preventing seed set to deplete the seed bank (2014)
GRDC video links
Webinar on the latest research in managing wild radish (2014)
Windrow burning beats wild radish (GRDC Over The Fence: Rod Messina, 2013)
Controlling seed set of wild radish (Raphanus raphanistrum L.) with herbicide application during reproduction Aik Cheam and Siew Lee p. 312, 17th Australasian Weeds Conference (2010) (CAWS)