Small-seeded Alfalfa Dodder

Cuscuta planiflora Ten.

Family: Convolvulaceae (was Cuscutaceae)

Names:

Cuscuta is from the Arabic word meaning "to bend" and refers to the twining habit of the stems. Dodder is from the German word for "egg-yolk" and refers to the yellow stem colour.

Other names:

Summary:

Dodders are leafless, thin stemmed plant parasites that usually have little or no chlorophyll. They twine around the host plant and attached suckers (haustoria) to remove nutrients from the host.

Description:

Cotyledons:

Two. Rudimentary or none.

Leaves:

None or inconspicuous scales.

Stems:

Yellow, green or pink. Twining. Many branched. Attach to host plant by small suckers (haustoria) to obtain moisture and nutrients. Thread like. Up to 1000 mm long.

Flower head:

Clusters of flowers along the stem.

Flowers:

White. Bell shaped. 3-4 mm round.

Fruit:

Globular capsule. 3-4 mm round with 1-4 seeds. Opens by an irregular line around the middle.
Seeds: Brown, yellow or grey. Globular but flattened on one side. 1- 2 mm round. Rough seed coat. Triangular pyramid shaped.

Seeds:

Small.

Roots:

None or very small. Dies away after stem attachment.

Key Characters:

Thin, leafless, twining, brown to yellow stems.

Biology

Life cycle:

Annual. Seeds germinate mainly in winter to spring. Seedlings have no roots and soon die unless they contact the stem of a suitable host plant to parasitise. Twining stems engulf the host plant quickly. Flowering and seeding occurs in September to October so dodder seed may be harvested with the crop in early summer. Seed probably lasts in the soil for at up to 5 years. Most spread is by seed as a contaminant of produce or in water or by passing in animal droppings. Stem fragments can move in water or on machinery and invade new hosts. Large amounts of seed are produced.

Physiology:

Reproduction:

Flowering times:

September to October.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

Mediterranean.

Distribution:

ACT, QLD, SA, WA.
In WA in Carnarvon, Murchison and Geraldton Sandplain regions

Courtesy Australia's Virtual Herbarium.

Habitats:

Grows wherever host survives.

Climate:

Soil:

Often on clay flats and hills.

Plant Associations:

Significance:

Beneficial:

Detrimental:

It will parasitise various plants including canola.
Can seriously reduce the yields or marketability of crops.

Toxicity:

Fodder infested with related species may cause scouring and cattle deaths have been recorded overseas, but don't seem to occur in Australia. It is probably relatively unpalatable.

Symptoms:

Scouring.

Treatment:

Prevent stock access to infested areas or fodder.

Legislation:

Noxious weed of SA, TAS, VIC, WA.

Management and Control:

Burn after spraying with diesel and/or cultivate. The herbicide diquat, amitrole and glyphosate can be used if applied before flowering. Repeat sprays are required. Metsulfuron, clopyralid and propyzamide have more selective action. Fumigation with chlorinated hydrocarbons is effective and expensive. Methyl bromide is ineffective. Various mulches provide some control in perennial or transplanted crops. A number of biocontrol agents have been investigated and a fungal preparation is used on soybeans.

Thresholds:

Eradication strategies:

Remove host plants for 3 to 5 years or grow crops or pasture species that are not attacked.
Grass pastures or crops such as the cereals are normally used. Good control of broadleaf weeds in these crops is essential to stop Dodder surviving. In areas that can't be cropped, application of picloram based herbicides provides residual control of broadleaf plants with little effect on grasses. Patches can be treated by spraying host plants, plus a 5 metre buffer area, until just wet, with a mixture of 1 litre of Grazon plus 250 mL Pulse® Penetrant per 100 litres of water. Repeat this annually for five years or when broadleaf plants germinate.

Herbicide resistance:

Biological Control:

Related plants:

Australian Dodder (Cuscuta australis)
Fringed dodder (Cuscuta suaveolens) not in WA.
Golden Dodder (Cuscuta campestris)
Greater Dodder (Cuscuta europaea)
Lesser Dodder (Cuscuta epithymum)
Tasmanian Dodder (Cuscuta tasmanica)
Cuscuta victoriana.

Plants of similar appearance:

Dodder Laurels (Cassytha species) are native plants and usually grow on native hosts, usually have at least some green on their stems, are rarely as golden as Golden Dodder, have 3 petals rather than 5 lobed flowers and tend to be perennial.

References:

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

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

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #306.5.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P400-403

Acknowledgments:

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