celebrates the horticultural publisher K.L. Hirschfeld. Incana is from the Latin word meaning 'grey' referring to the colour of the leaves and stem.
Buchan weed - probably refers to the presence of this weed along the Buchan River in Victoria.
Other names:Hoary Mustard
Hairy Brassica (USA)
Shortpod Mustard (USA).
Summary:Stout, erect, bristly, annual to perennial herb with spreading branches, stalked leaves and 4 petalled yellow flowers that bear pods held close to the stem.
Two. Heart shaped. Tip indented. Edges smooth. Base tapered. Petiole about as long as the blade.
First leaves:Oval, edges irregularly toothed and lobed. Sometimes purple near the base or with purple veins. Short petiole. Hairy.
Leaves:Grey-green with indented veins. Forms a rosette.
Petiole - Long on lower leaves, shorter to almost absent on uppermost leaves.
Blade - Whitish or mealy, dense stiff hairs pressed close to the leaf surface. Lower leaves are deeply lobed with coarse rounded teeth. The end lobe is larger than the others and egg shaped. Lower leaves up to 200 mm long.
Stem leaves - Oval, with short teeth on the edges. Almost hairless. Uppermost leaves have no petiole and clasp the stem.
Stems:Flowering stems - Grey-green, erect, single or with spreading branches, stout, 300-1500 mm tall. The lower half is covered with stiff white downward pointing hairs.
Flower head:Panicle about 300 mm long, at the ends of branches in small groups held higher than the top leaves. New flowers open as old ones wither and form pods leaving a string from ripening pods at the bottom to flower buds at the top.
Flowers:Pale yellow, 12-16 mm diameter, on a short thick stalk.
Sepals - Erect, above the buds that lengthen to form the pod.
Petals - 4, yellow, often with purple veins, 6-8 mm long.
Fruit:2 celled, almost cylindrical, flattened pod, 5-17 mm long, 1-2 mm wide with a thick beak 2-5 mm long. The pod is on a short thick, erect stalk (2-4 mm long) held close to the stem. The beak is swollen near the base and tapering to a coned, flat-topped tip. 3-9 seeds in each cell and one, or rarely two, in the beak. Two sides break away from the central partition from the base upwards when ripe, releasing the seed. Cells hard, 3 nerved when young.
Seeds:Egg shaped. Reddish brown, dull. 1 mm diameter. Tip round. Base indented. Surface smooth.
Roots:Slender, deep taproot with branching laterals in the top 300 mm of soil.
Key Characters:Short pods pressed against the stem with a seed or two in the beak. 3 nerved valves that release seed at maturity. Seeds in 1 row. Yellow flowers with 4 petals. Cotyledons folded flat.
Annual, biennial or perennial. Seeds germinate from autumn to spring and produce a rosette of leaves that grow slowly. Flowering stems emerge in mid-winter and flowering starts in September and may continue to February under good conditions. The top growth dies with the on-set of summer drought, leaving the perennial root stock. This shoots with the opening rains in autumn.
By seed and from roots.
Flowering times:September to February in SA.
Summer in ACT.
Winter to spring in western NSW.
Seed Biology and Germination:Seed won't germinate for a month after maturity. The seed coat contains germination inhibitors.
Population Dynamics and Dispersal:
By seed, usually in mud clinging to stock or vehicles, or as a contaminant in cereal and other grain. Flood waters and road works spread small quantities.
Usually grows in small patches but may form dense infestations in cultivated or disturbed areas.
Origin and History:Mediterranean and Channel Islands.
Introduced to NSW in the late 1800's.
First recorded at Bathurst in 1903.
Distribution:ACT, NSW, QLD, SA, TAS, VIC.
Courtesy Australia's Virtual Herbarium.
Temperate regions to sub alpine levels.
Soil:Common on heavy and fertile soils.
Stock will eat it when it is young, but it becomes tall, coarse and unpalatable at maturity.
Detrimental:Weed of disturbed areas, roadsides, railways, natural pastures, fallows, irrigated pasture, bush land, orchards and vineyards.
In winter cereals it competes with the crop, interferes with harvesting equipment and contaminates the grain.
Taints milk and meat.
Toxicity:Not recorded as toxic.
Legislation:Noxious weed of SA.
Management and Control:Manually remove isolated plants.
Prevent seed set. Spray small infested areas with 10 g/ha Eclipse® plus 500mL/ha of Brodal® plus 1% spray oil in winter each year.
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 under-grazed, 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 Brassicaceae species though Wild Radish tends to regrow.
Mechanically remove isolated plants including the top 200 mm of root and burn. Spray a 10 metre area around these plants with 1 L/ha of Brodal (diflufenican).
Deep ploughing kills the perennial taproot. Follow up cultivations are required to kill seedlings. Establishing vigorous pasture species will reduce re-infestation. Odd plants can be removed mechanically providing the taproot is not broken off. Hormone herbicides and metribuzin control seedlings in various crops. Spray-Graze using 2,4-D amine or MCPA plus diflufenican (e.g. Tigrex®) provides useful control in legume based pastures.
Herbicide resistance:Biological Control:
None in the same genus.
Flax-leaf Alyssum (Alyssum linifolium)
Wall Cress (Arabidopsis thaliana)
Black Mustard (Brassica nigra)
Broccoli (Brassica oleracea var. italica)
Brussels Sprouts (Brassica oleracea var. gemmifera)
Cabbage (Brassica oleracea var. capitata)
Cauliflower (Brassica oleracea var. botrytis)
Chinese Cabbage (Brassica chinensis)
Indian Mustard (Brassica juncea)
Kale (Brassica oleracea var. acephala)
Kohlrabi (Brassica oleracea var. gongylodes)
Mediterranean Turnip (Brassica tournefortii)
Rape or Canola (Brassica napus var. napus)
Rapeseed (Brassica rapa var. sylvestris)
Savoy cabbage (Brassica oleracea var. sabauda)
Smooth Stemmed Turnip (Brassica barrelieri subsp. oxyrrhina was Brassica oxyrrhina)
Swede (Brassica napus var. napobrassica)
Turnip (Brassica rapa var. rapa)
Twiggy Turnip (Brassica fruticulosa)
Winter Rape (Brassica napus var. biennis)
Sea Rocket (Cakile maritima)
White Ball Mustard (Calepina irregularis)
Shepherd's Purse (Capsella bursa-pastoris)
Common Bittercress (Cardamine hirsuta)
Wood Bittercress (Cardamine flexuosa) is not in WA.
Ward's Weed (Carrichtera annua)
Wall Rocket (Diplotaxis muralis)
Sand Rocket (Diplotaxis tenuifolia)
Oval Purse (Hornungia procumbens was Hymenobolus procumbens)
Argentine Peppercress (Lepidium bonariense) is often found around granite rocks.
Common Peppercress (Lepidium africanum) is common in WA.
Field Cress (Lepidium campestre) has clasping stem leaves.
Garden Cress (Lepidium sativa)
Hoary Cress (Lepidium draba was Cardaria draba)
Lesser Swinecress (Lepidium didymum was Coronopus didymus)
Matted Peppercress (Lepidium pubescens)
Perennial Peppercress (Lepidium latifolium)
Virginian Peppercress (Lepidium virginicum)
Sweet Alyssum (Lobularia maritima)
Common Stock (Matthiola incana)
Night-scented Stock (Matthiola longipetala)
Muskweed (Myagrum perfoliatum) is not in WA.
Ball mustard (Neslia paniculata)
Cultivated Radish (Raphanus sativus).
Sea Radish (Raphanus maritimus).
Turnip Weed (Rapistrum rugosum)
Watercress (Rorippa nasturtium-aquaticum)
White Mustard (Sinapis alba) has white seed.
Charlock (Sinapis arvensis)
Sisymbrium altissimum is not in WA.
Smooth Mustard (Sisymbrium erysimoides)
London Rocket (Sisymbrium irio)
Hedge Mustard (Sisymbrium officinale)
Indian Hedge Mustard (Sisymbrium orientale)0
African Turnip Weed (Sisymbrium thellungii) is not in WA.
Succowia balearica is in Kings Park in Perth.
Plants of similar appearance:Radishes, mustards and turnips.
References:Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P134. Diagram. Photos.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P378.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P181, 183. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P325. Photo.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #650.1.
Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P68. Diagrams. Photos.
Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P344-346. Photos.
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.