Title: Cardaria draba (L.) Desv.

Scientific name:

Cardaria draba (L.) Desv.

Common name(s):

hoary cress, whitetop

hoary cress plant (source: DPI Victoria) Hoary Cress Flowers (source: DPI Victoria)


Habitat: Warm-temperate regions occurring in dry, unshaded situations on uncultivated, heavy, fertile soils up to subalpine levels (Parsons and Cuthbertson 1992). It occurs as a weed of cereal crops, pastures, roadsides and neglected sites in areas with an annual rainfall exceeding 400 mm (Parsons and Cuthbertson 1992).

Distribution:



Original source via Macquarie University


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? Seeds germinate in autumn. (Parsons and Cuthbertson, 1992)

2. Establishment requirements? All the hoary cresses grow under similar open unshaded conditions, (Mulligan & Findlay (1974)).

3. How much disturbance is required? Establish in vigorously growing crops e.g. wheatlands, (Mulligan & Findlay (1974)).

GROWTH / COMPETITIVE


4. Life form? Erect perennial herb. Geophyte → aerial growth dies in summer with new growth in autumn/spring, (Parsons and Cuthbertson, 1992)

5. Allelopathic properties? Serious effects on wheat & barley, (Qasem, 1994 ; Qasem, 1995)

6. Tolerates herb pressure? Consumed but not always preferred. Capable of rhizome production under moderate herbivory assumed, (McInnis et al.,1993)

7. Normal growth rate? Hoary Cress is a strong competitor in the plant world & being more hardy than most cultivated plants, causes appreciable reduction in yield of both pasture & crops, (Meadly, 1965).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerant of fire (heat presumably breaks seed dormancy), waterlogging (occurs along river), drought (occurs on semi arid rangelands). Also tolerates freezing conditions (frost) as occurs in very cold climates such as Finland (Lyons n.d.), (FEIS; Hetzel, 1985).

REPRODUCTION


9. Reproductive system? Reproducing from perennial roots & by seed, (Parsons and Cuthbertson, 1992).

10. Number of propagules produced? A single plant can produce b/w 1,000-5,000 seeds with a viability of ~80%, (P&C, 1992).

11. Propagule longevity? Seed viability rapidly declines with age of seed. 0% seeds germinate after 3 years, (Lyons (n.d)).

12. Reproductive period? Forming large patches (monocultures formed). Very dense patches may be found in some areas of Southern Australia. See pic P&C 1992 p.340., (Webb et al.,19988; P&C, 1992)

13. Time to reproductive maturity? Plants do not usually flower in the first year, assumed to flower in 2nd year, (Parsons and Cuthbertson, 1992).

DISPERSAL


14. Number of mechanisms? The main method of dispersal is by movement of pieces of cut root adhering to mud or caught on the lines of cultivation equipment. Seed also dispersed by stock, farm machinery & vehicles, in hay, silage & grain & in water (Anon), (Parsons and Cuthbertson, 1992; Anon).

15. How far do they disperse? Many propagules caught in cultivation equip are likely to reach 200-1,000 m.


Impact Assessment

RECREATION


1. Restrict human access? An erect herb, 15 to 75 cm high, with aerial growth dying in summer. Its presence in dense patches would be a nuisance to pedestrian traffic, (Parsons and Cuthbertson, 2001)

2. Reduce tourism? Dense infestations would have a minor effect on aesthetics, and may reduce some recreational activities, (P & C, 2001).

3. Injurious to people? Stock losses from grazing the plant have occurred, but are rare. “…the seeds were ground and used as a substitute for pepper and the leaves are eaten as a vegetable in Afghanistan.” Not known to be poisonous to humans; no spines or burrs, (P & C, 2001).

4. Damage to cultural sites? Dense patches likely to create a negative visual impact. The root system is extensive, but not vigorous. Unlikely to cause structural damage, (Parsons and Cuthbertson, 2001).

ABIOTIC


5. Impact flow? Terrestrial species. “…occurring in dry, unshaded situations.", (P & C, 2001).

6. Impact water quality? Terrestrial species, (P & C, 2001).

7. Increase soil erosion? Root system comprises, “A main root to 2 metres or more deep with numerous horizontal roots.” However, aerial parts of the plant die back in summer leaving surface soil exposed to erosion, (Parsons and Cuthbertson, 2001)

8. Reduce biomass? “It occurs as a weed of cereal crops, pastures, roadsides and neglected sites.” In these situations, biomass may increase, (P & C, 2001).

9. Change fire regime? “Aerial growth dies in summer.” Possible increase in dry matter leading to minor change in the frequency of fire risk, (P & C, 2001).

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC= Plains grassland (E); CMA=West Gippsland; Bioreg=Highlands – Southern Falls; VH CLIMATE potential. Not known as a weed in natural ecosystems (not recorded in Carr et al 1992), however, in the United States it is known to compete aggressively with native vegetation. “…eventually eliminates the desirable plants completely.” Possible monoculture within the lower stratum. Australian experience: more a weed of agriculture, (Downs (n.d.)).

10(b) Impact on medium value EVC? EVC= Grassy woodland (D) CMA=West Gippsland; Bioreg=Highlands – Southern Falls; VH CLIMATE potential. As above, however, as species grows best in unshaded situations, population density may be restricted. In Australia, it occurs in dry unshaded situations. Minor displacement of indicator spp. in lower stratum, (Downs (n.d.)).

10(c) Impact on low value EVC? EVC= Heathy woodland (LC); CMA=Port Phillip; Bioreg=Gippsland Plain; VH CLIMATE potential. Impact as in 10(b) above, (Downs (n.d.)).

11. Impact on structure? “It also occurs commonly in pastures and market gardens in many parts of Australia but is not as competitive in these situations as in cereals.” In the US State of Montana C. draba, “…is a very aggressive plant. It is competitive with the native plants and eventually eliminates the desirable plants completely.” “It is found most often in open, unshaded areas.” Would have a major impact on the lower stratum (ground covers, grasses, forbs), (P & C, 2001 ; Downs (n.d.) ; Esser (1994).

12. Effect on threatened flora? None documented.

FAUNA


13. Effect on threatened fauna? None documented.

14. Effect on non-threatened fauna? In the US State of Montana C. draba, “…is a very aggressive plant. It is competitive with the native plants and eventually eliminates the desirable plants completely.” “The plant…is seldom eaten by stock.” Potential to significantly reduce food source of native fauna, (Downs (n.d.) ; P & C, 2001).

15. Benefits fauna? No known benefits

16. Injurious to fauna? The plant, “is potentially mildly toxic.” Fauna may lose condition, (Esser, 1994).

PEST ANIMAL


17. Food source to pests? Not known as food source to pests.

18. Provides harbor? “Aerial growth dies in summer.” In pasture/grassland situations, it may provide some limited harbor to pest animals such as rodents, (P & C, 2001).

AGRICULTURE


19. Impact yield? “In early trials with 2,4-D in the Victorian Wimmera, treated plots yielded 20% more wheat than the plots where hoary cress was unchecked.” The plant has serious impact on crop yields, (Parsons and Cuthbertson, 2001)

20. Impact quality? “…it is seldom eaten by stock. When it is eaten, however, milk and possibly meat are tainted,"(Parsons and Cuthbertson, 2001)

21. Affect land values? Due to the limited control methods available during the 1930s, presence of the weed in cropping situations, “…greatly reduced land value.” In spite of improvements to control methods, its occurrence in paddocks today would most likely reduce the land value, (P & C, 2001).

22. Change land use? “Fortnightly cultivations killed all plants after 2 years.” Temporary loss of land for productive activities that would lead to significant loss, (Parsons and Cuthbertson, 2001)

23. Increase harvest costs? “…it also interferes with harvesting in some areas.” Interference may increase either time or labour to conduct harvest, (P & C, 2001).

24. Disease host/vector? In the US, Cardaria spp. have been found to host viral pathogens that cause beet western yellows and potato leaf roll. Potential threat to Victorian producers?, (Jewett, 2003).




Feedback

Do you have additional information about this plant that will improve the quality of the assessment? If so, we would value your contribution.


Assessment ratings originally made by the Victorian Department of Primary Industries.
The entry of this assessment was made possible through the generous support of The Weed's Network.






Attachments:
hoard_cress_plant.jpg
hoary_cress_flowers.jpg
dot_black.gif
dot_blue.gif
dot_red.gif
dot_purple.gif
dot_yellow.gif
Capture.JPG
Related Articles
referenced by (2)
wra1040: Common Name - W (via whitetop)wra1002: Common Name - H (via hoary cress)
Article: wra2046 (permalink)
Categories: :wra:c, :wra:inv1, :wra:invmh, :wra:inv2, :wra:invml, :wra:inv3, :wra:inv4, :wra:inv5, :wra:inv6, :wra:inv7, :wra:invh, :wra:inv8, :wra:inv9, :wra:inv10, :wra:invl, :wra:inv11, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impml, :wra:imp2, :wra:imp3, :wra:impl, :wra:imp4, :wra:imp5, :wra:imp6, :wra:imp7, :wra:imp8, :wra:imp9, :wra:imp10a, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imph, :wra:imp16, :wra:imp17, :wra:imp18, :wra:imp19, :wra:imp20, :wra:imp21, :wra:impm, :wra:imp22, :wra:imp23, :wra:imp24
Date: 13 October 2009; 12:35:59 PM AEDT

Author Name: Niharika Anand
Author ID: anandn