Red Spot Fleabane

Conyza parva Cronq.

Synonyms -

Family: Asteraceae.

Names:

Parva means small and refers to the size of the flower heads compared to other Conyza species.
Red Spot Fleabane - because the bracts surrounding the florets often have a red spot on their tips and some plants in this family repel insects or fleas.

Other names:

Fleabane
Horsetail

Summary:

Red Spot Fleabane is an erect annual with the upper part of the plant forming a pyramid of flowers and fluffy seeds on top of the leafy and usually unbranched stem which is often about 0.5 m tall. It has a short lived rosette at the base and the leaves are almost hairless. The bracts surrounding the flower head are usually red tipped.

Description:

Cotyledons:

Two.

Leaves:

Alternate. Light yellow green. Forms a rosette that usually dies before flowering.
Petiole - Petiole-like base on leaves.
Blade - (5)30-45 mm long x 1-5 mm wide, Edges recurved or flat and entire or with shallow rounded teeth. Parallel sided to oblong or narrowly oval, narrowing into a petiole-like base. Almost hairless or with sparse very fine hairs (ciliate). Finely scabrid on margins. Tip pointed. Edges shallowly lobed or parallel sided or slightly curved. Base tapering.
Stem leaves - 5-40 mm long, narrow, lance shaped, smooth edges.

Stems:

0.2-2.5 m tall, usually about 0.5 m tall. Erect. Unbranched below the flower head, Maybe branched from the base. Almost hairless. Leafy.

Flower head:

Open, branching inflorescence with 1 to several, cylindrical, dense, spike-like panicles. Branches of panicle short with up to 10 heads in each panicle.

Flowers:

Heads bell shaped, 3-4 mm long x (1)3-5 mm diameter on slender flower stalks (peduncles).
Bracts - Involucre bracts in 4 rows, 3-4 mm long, narrow, oblong to narrowly oval, hairless to sparsely hairy, with pale edges and inner surface pale cream often with a red-purple tip. Tip pointed.
Florets - Many outer (ray) ones with a short, 1 mm long, narrow, obvious, whitish or purple tinged appendage (ligule).
About 4 disc florets that are white or tinged purple. Tubular.
Receptacle is pitted and 1-1.5 mm diameter.
Ovary -
'Petals' - Short, whitish or purple tinged.
Stamens -
Anthers -

Fruit:

Achene. Narrowly oval with thickened edges, 1-1.5 mm. Pale yellow to bright orange. Sparsely hairy.

Seeds:

Pappus of cream to pale straw coloured, minutely barbed bristles, 2-3 mm long.

Roots:

Taproot.

Key Characters:

Leaf margins entire or crenate, recurved.
Stems not conspicuously hairy.
Flower heads pedunculate in large panicles not subtended by a whorl of leaves.
Involucre bracts usually with an apical red spot.
Involucre bracts pale cream on the inner surface.
Involucre bracts glabrous or almost so.
Heads campanulate.
Outer florets with short, but visible, white ligules.
Achenes lacking a long beak.
Adapted from G. Harden. J. Wheeler.

Biology:

Life cycle:

Annual.

Physiology:

Reproduction:

By seed.

Flowering times:

February to March in Perth.
January to March in WA.
Most of the year in SA.
Summer to autumn in NSW.

Seed Biology and Germination:

Closely related species are viable in the soil for 1-2 years, germinate at 15-25 degrees C in light and dark conditions.

Vegetative Propagules:

None.

Hybrids:

Probably.

Allelopathy:

Population Dynamics and Dispersal:

Wind spreads seed.

Origin and History:

South America.

Distribution:

NSW, QLD, SA, VIC, WA.
Jarrah Forest, Warren, Swan Coastal Plain regions in WA.
Lord Howe Island.

Courtesy Australia's Virtual Herbarium. (Conyza parva 2008).

Habitats:

Roadsides, disturbed bushland.

Climate:

Temperate.

Soil:

Wide range of soils, prefers sands.

Plant Associations:

Significance:

Beneficial:

Detrimental:

Weed of roadsides, disturbed areas.

Toxicity:

Not recorded as toxic.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Grazing should provide 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:

This species appears to have a more Iimited distribution than other Conyza. 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:

Chilean Fleabane (Conyza chilensis)
Flaxleaf Fleabane (Conyza bonariensis) is very similar but has long hairs near the tips of the flower bracts.
Rough Conyza (Conyza scabiosifolia)
Tall Fleabane (Conyza albida) has densely hairy involucre bracts.
Conyza bilbaoana is very similar and has almost globular flower heads, outer florets are thread like with an inconspicuous appendage and has hairless triangular flower head bracts.
Conyza parva is very similar but has almost hairless stems, hairy leaf margins, cylindrical flower head and involucre bracts are narrow, oblong, hairless and usually have purple/red apical spots.
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). P96.

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 3. P198. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (2007). Western Weeds. A guide to the weeds of Western Australia. (Second Edition). Plant Protection Society of Western Australia, Perth, Western Australia. P92. Photo.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #274.8.

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.

Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P6-67. Photos.

Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P160.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Wheeler, Judy, Marchant, Neville and Lewington, Margaret. (2002). Flora of the South West: Bunbury - Augusta - Denmark. (Western Australian Herbarium, Bentley, Western Australia). P501-502. Diagram.

Acknowledgments:

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