Invasiveness Assessment - Whiskey grass (Andropogon virginicus) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of Whiskey grass.

A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:

Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1 MB)
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Common Name: Whiskey grass
Scientific name: Andropogon virginicus

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	Germination for this species occurs in Autumn (Parsons & Cuthbertson 2001).	MH	MH
Establishment requirements?	The species often occurs on disturbed sites and is reported to be intolerant of shade (Parsons & Cuthbertson 2001; PFAF 2007; Restrepo & Vitousek 2001).	ML	MH
How much disturbance is required?	The species invades habitats which are considered highly disturbed such as roadsides and overgrazed native pasture (Parsons & Cuthbertson 2001).	ML	MH
Growth/Competitive
Life form?	Grass; the species is a C4 perennial bunchgrass (Marks & Strain 1989).	MH	H
Allelopathic properties?	The species has been found to have significant inhibitory effect on the growth of seedlings of a number of species (Rice 1972). Reported to have some allelopathic properties (Rice 1984).	MH	H
Tolerates herb pressure?	The species is reported to have little fodder value and that the dried biomass can present as a fire hazard in late summer, which would indicate that largely the species isn’t consumed (Parsons & Cuthbertson 2001). The species is considered unpalatable and of low forage value (Griffin, Watson & Strachan 1988).	MH	H
Normal growth rate?	Reported to have a slow growth rate through winter, plants are then able to grow to 1 m high during spring and summer (Parsons & Cuthbertson 2001). The species is therefore considered to have a growth rate equal to that of other grass species.	M	MH
Stress tolerance to frost, drought, w/logg, sal. etc?	Reported to occur in ephemeral wetlands (Kirkman & Sharitz 1994). Therefore the species has some tolerance to waterlogging. The species can persist through fire events (D’Antonio, Tunison & Loh 2000). Tolerant of drought (Marks & Strain 1989). Tolerant of heavy metals (Gibson & Risser 1982). Tolerant of frost, Reported to be hardy to zone 6 (-20°C) (PFAF 2007).	H	H
Reproduction
Reproductive system	The species reproduces sexually producing seed (Parsons & Cuthbertson 2001).	ML	MH
Number of propagules produced?	Unknown.	M	L
Propagule longevity?	Unknown.	M	L
Reproductive period?	The species is reported to persist in almost pure stands for many years (Rice 1972).	H	H
Time to reproductive maturity?	The species is able to reproduce in its first year (Parsons & Cuthbertson 2001).	H	MH
Dispersal
Number of mechanisms?	The species seeds are reported to be dispersed externally on animals and with human aided dispersal (Parsons & Cuthbertson 2001).	MH	MH
How far do they disperse?	This species is spreading into Eastern Victoria through the movement of hay and livestock from NSW, which enables the species to be spread more than 1 km (Sexton 2003).	H	H

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