Tall Fleabane

Conyza sumatrensis (Retz.) E.Walker

Synonyms - Conyza albida, Erigeron albida, Conyza floribunda?

Family: Asteraceae.

Names:

Tall Fleabane refers to its height and the insect (flea) repelling properties of the ground seed.

Other names:

Fleabane.

Summary:

An erect, hairy, leafy, annual plant to 2 metres tall that has a single stem that is usually unbranched below the inflorescence but many branched near the top into a pine tree shape carrying small greenish white flowers that produce fluffy seed. It has a basal rosette of entire or toothed, hairy leaves and an erect, often greyish, leafy flowering stem. The small flower heads are cream to white and do not have the radiating petal-like florets seen in many daisies. Instead there are several slender tubular florets. Tiny fruits are topped by a ring of bristles. It is native to North America and flowers in the summer and autumn.

Description:

Cotyledons:

Two.

Leaves:

Alternate.
Petiole - None.
Blade - Oval, 100 mm long x 15 mm wide. Edges often toothed. Lower leaves usually have deeper teeth than the upper leaves. Few hairs.
Stem leaves - Elliptical. May have toothed edge. Up to 100 mm long x 15 mm wide. No stalks. Few hairs.

Stems:

Slender, erect, round, striped, up to 2000 mm tall, very leafy, branched near top into a dense, pyramidal, compound, pine tree shaped flowering structure. Side branches are never higher than the central stem. Roughly hairy.

Flower head:

Borne on ends of stems in clusters.
Disc form. Usually less than 10 mm diameter when dry.

Flowers:

White or pale yellow.
Bracts - Dark and pale, sometimes purple tipped, red brown on the inside when bent back. About 3 rows, narrowly oval, sparsely hairy, papery edges, tapering pointed tip,
Florets - Marginal ones white or pale yellow, tubular, no 'petals' (ligules) or very tiny ones.
Ovary -
'Petals' - None or very tiny.
Stamens -
Anthers -

Fruit:

Elliptic, achene, 1.3 mm long with thickened pale edges. Pappus of rough straw coloured bristles. Sparsely hairy.

Seeds:

Roots:

Taproot.

Key Characters:

Flower bracts are hairy but there are no long hairs near the apex.

Biology:

Life cycle:

Annual up to 2 m. Germinates autumn/winter/spring. Flowers January to late-winter/spring/summer

Physiology:

Reproduction:

By seed.

Flowering times:

August to January in WA.

Seed Biology and Germination:

Seed germinates from 10 to 25 degrees C (Zinzolker et al., 1985).

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Seed is spread by wind.
It is a common contaminant of nursery plants.

Origin and History:

South America.

Distribution:

WA, NSW, QLD, SA, TAS, VIC, WA.

Conyza albida.
Courtesy Australia's Virtual Herbarium.


Conyza sumatrensis.
C. floribunda is in the ACT.
Courtesy Australia's Virtual Herbarium

Habitats:

Climate:

Temperate.

Soil:

Wide range.

Plant Associations:

Wide range.

Significance:

Beneficial:

Pollen for bees.
Fodder but rarely eaten if other feed is available.

Detrimental:

Weed of crops, cultivation, roadsides and disturbed areas.

Toxicity:

Suspected of poisoning stock.
Taints milk.

Legislation:

None.

Management and Control:

Grazing often provides reasonable control.
Control seed set.
Seeds readily spread by wind.
Appears to be reduced in systems using group B herbicides. e.g. metsulfuron in late winter or chlorsulfuron, Spinnaker® or Flame® in early winter and where atrazine (group C) has been used.
Crops treated with clopyralid mid-season usually have reduced fleabane infestations due to residual herbicide action.
Reduce row width and increase crop planting rates to reduce the amount and duration of bare area.
Improve agronomy and choose competitive crop and pasture varieties to provide quick cover and consume all the spring moisture. Avoid Chickpea, dryland Cotton and Sunflowers in infested areas.
Cultivate to control mature and/or stressed plants.
Bury seed more than 2 cm deep by inversion ploughing.
Spray at the seedling stage of the weed with glyphosate plus metsulfuron plus 2,4-D or glyphosate plus high rates of 2,4-D or amitrole. Paraquat/diquat plus atrazine, Garlon® plus picloram and dicamba have also given good results. Early treatment with imazapic or Spinnaker can provide residual control in fallows or IT crops. Chlorsulfuron, metsulfuron, dicamba, 2,4-D or 2,4-D/picloram are useful in cereals. Pre harvest sprays with 2,4-D after cereals have reached the firm dough stage can provide good suppression of pre summer germinations.
In wheat, pre plant chlorsulfuron plus a late application of 2,4-D usually provides good economic control. A follow up treatment in summer may be needed for fleabane germinating after the last spray.
In Sorghum use atrazine + paraquat/diquat pre plant then atrazine + fluroxypyr with dropper nozzles in crop.
In Chickpeas use imazapic in the fallow then isoxaflutole + simazine pre planting.
In dryland Cotton, diuron, fluometuron and prometryn are the best bets pre planting followed by bromoxynil pre emergence or inter-row cultivation post emergence.
Paraquat/diquat provides desiccation but plants normally regrow from axillary meristems within a month.
Amitrole has provided good control of seed set on plants that have elongated.
Much higher rates of most herbicides are required after stem elongation.
Growing conditions before and after spraying and the growth stage of the weed have a major influence on the level of control achieved by herbicides.
Increasing the water volume from 100 to 200 L/ha at spraying had no effect on glyphosate performance.
Split spraying has generally provided better control than single applications.

Thresholds:

Eradication strategies:

Spray road shoulders with 2-3 L/ha glyphosate(450g/L) plus wetting agent in early summer to reduce the spread of seed in the slipstream of traffic. On other areas, apply 1 L/ha glyphosate(450g/L) after stem elongation and before flowering in late spring to summer each year when the plants are actively growing. A mixture of 1 L glyphosate(450g/L) plus 2 L water can be used to wipe the stems of plants. Lontrel®750 at 200 g/ha or 4 g plus 25 mL wetting agent in 10 L water can be used for fairly selective control in bushland. Isolated patches can be sprayed with a mixture of 50 mL Tordon®75-D in 10 L water for control of plants and residual control of seedlings. Hand pulling after stem elongation is effective on loose soils, but on heavier soils a weed fork is required to prevent the plant breaking and regrowing from the base. Mowing is not effective.
Planting perennial species to increase ground cover and shade will help reduce re-infestation. Continuous grazing usually gives adequate control.

Herbicide resistance:

Biological Control:

Related plants:

Canadian Fleabane (Conyza canadensis)
Chilean Fleabane (Conyza chilensis)
Flaxleaf Fleabane (Conyza bonariensis) is very similar but branches from near the base rather than the top and has long hairs near the tips of the flower bracts. It is usually shorter and greyer than Tall Fleabane (Conyza albida)
Rough Conyza (Conyza scabiosifolia)
Conyza parva
Conyza sumatrensis

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P95. Photo.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P662. 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). #346.1.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P672.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.