White Ball Mustard Calepina irregularis (Asso.) Thell.
Family: - Brassicaceae
A weak stemmed, lobed leaved, rosette, annual or perennial herb with 4 petal white flowers that form small ball like fruit on stalks up the flowering stem.
Two. Oval. Tip flat to round. Base tapered. Edges smooth. Petiole long. Hairless smooth surface.
Oval. Edges lobed. Tip round. Irregular purple blotches on the upper surface. Hairless. Petiole long. Third leaf has deeply undulating edges.
Form a rosette.
Petiole - Very short or none on lower leaves, none on upper leaves.
Blade - Broadly oval, toothed or deeply lobed. Tip rounded. Base tapered.
Stem leaves - Alternate. Pointed tip. Slightly toothed or smooth edges. Base stem clasping.
Flower stem - Weak, spreading branches.
Single flowers alternate on stem.
Small and white, 4 petalled on short stalks (peduncles).
Ovary - Superior.
Sepals - 4.
Petals - 4. White.
Ball shaped pod, green turning yellow on maturity. On short stalks.
Enclosed in yellow to brown pod. .Spherical to tear shaped, 1.5-2.5 mm diameter. Tip rounded. Base pointed. Surface hairless, ridged with a network pattern.
Ball like fruit on short pedicels.
Annual or perennial. Seeds germinate in autumn to winter.
Seed Biology and Germination:
Population Dynamics and Dispersal:
Spread by seed.
Origin and History:
Weed of pastures and crops.
Management and Control:
Most of the Brassicaceae weeds have dormant seeds that continue to germinate throughout the season and for several years. They often mature and set seed very quickly. Manual removal is effective but must be done at least every 8-10 weeks. Once pods are formed, seed will often mature even if the plant has been uprooted. Soil disturbance often leads to a flush of seedlings.
Many are somewhat unpalatable, so grazing only offers partial control. They often flourish in undergrazed, sunny areas.
In bushland situations, fairly selective control can be achieved with 100 mL spray oil plus 0.1 g Eclipse® or 0.5 g Logran® in 10 L water. 5 mL Brodal® is often added to this mix to provide residual control of seedlings. Spray the plants until just wet from the seedling stage up to pod formation.
Isolated plants should be removed manually and burnt if flowering or seeding and a 10 m buffer area sprayed with 10 mL Brodal® in 10 L water.
500 mL/ha of glyphosate(450g/L) can be used at flowering to reduce the seed set of most species on roadsides without causing significant damage to most native plants.
Wick application with 1 part glyphosate(450g/L) in 2 parts water or overall spraying with 100 mL glyphosate(450g/L) in 10 L water provides reasonable control of most species though Wild Radish tends to regrow.
The native Brassicaceae species usually have short, broad and smooth pods.
Plants of similar appearance:
Ball Mustard (Neslia paniculata) has a fruit with a shorter point on the tip.
Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).
Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume . P. Diagram.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #172.1
Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P65. Diagrams. Photos.
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.