Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Lolium multiflorum (annual ryegrass, Italian ryegrass)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

1

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

n

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

n

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

y

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

y

6.04

Self-compatible or apomictic

y=1, n=-1

n

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

1

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

y

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

n

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

y

7.08

Propagules survive passage through the gut

y=1, n=-1

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

n

8.03

Well controlled by herbicides

y=-1, n=1

y

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

n

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

9

Source

Notes

1.01

No evidence

1.02

Naturalized in the U.S. including Hawaii.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html

1.03

No evidence

2.01

(1) 'Italian ryegrass, native to Europe, has been introduced throughout the temperate regions of the world as an agricultural species. … Italian ryegrass occurs throughout the United States, including Alaska and Hawaii, and in adjacent Canadian provinces. Because of difficulties in distinguishing Italian ryegrass from perennial ryegrass, the exact northern distribution of Italian ryegrass is not well documented.' (2)It is an annual or biennial cool bunchgrass.

(1)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html (2)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

2.02

2.03

'Italian ryegrass occurs in grassland communities. It is a component of the California annual grasslands, a community composed of exotic grass species [6,28]. It occurs in a serpentine bunchgrass community, a freshwater seep community, …'

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html

2.04

(1) 'Italian ryegrass, native to Europe, has been introduced throughout the temperate regions of the world as an agricultural species. … Italian ryegrass occurs throughout the United States, including Alaska and Hawaii, and in adjacent Canadian provinces. Because of difficulties in distinguishing Italian ryegrass from perennial ryegrass, the exact northern distribution of Italian ryegrass is not well documented.' (2)It is an annual or biennial cool bunchgrass.

(1)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html (2)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

2.05

'Italian ryegrass, native to Europe, has been introduced throughout the temperate regions of the world as an agricultural species. … Italian ryegrass occurs throughout the United States, including Alaska and Hawaii, and in adjacent Canadian provinces.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html

3.01

Naturalized in the U.S. including Hawaii.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/distribution_and_occurrence.html

3.02

No evidence

3.03

(1) 'In Virginia, annual ryegrass has become one of the most troublesome and difficult to control weeds in small grains, as well as in corn and soybeans grown in rotation with small grains.' (2)Italian ryegrass is a serious weed in cereal crops and grass seed crops. (3) L. multiflorum is listed as a principal weed in several countries.

(1)http://216.239.53.100/search?q=cache:kpysAlEetbsC:www.ppws.vt.edu
/scott/weed_id/ryegrass.PDF+Lolium+multiflorum+&hl=en&ie=UTF-8 (2)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/value_and_use.html. (3)Holm et al. 1997. An electronic atlas of weeds and invasive species. CD-ROM database. Version 1.

3.04

No evidence

3.05

L. temulentum is a principal weed in Spain and Tunisia. L. perenne is a principal weed in New Zealand.

Holm et al. 1997. An electronic atlas of weeds and invasive species. CD-ROM database. Version 1.

4.01

No evidence

Wagner, W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii. University of Hawaii at Press. Honolulu.

4.02

Not allelopathic

http://plants.usda.gov/cgi_bin/topics.cgi

4.03

No evidence

4.04

(1) 'Meadow mice and white-tailed deer graze Italian ryegrass.' 'Italian ryegrass is palatable to livestock.' (2)a high-quality forage grass, regarding both the nutritious value and the digestibility.

(1)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/value_and_use.html (2)http://www.umweltbundesamt.org/fpdf-k/2103.pdf

4.05

a high-quality forage grass, regarding both the nutritious value and the digestibility.

http://www.umweltbundesamt.org/fpdf-k/2103.pdf

4.06

There are 107 fungi listed to be associated with this species.

http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm

4.07

No evidence

4.08

'Natural fires in Italian ryegrass stands are most likely to occur during the dry season when Italian ryegrass has already produced seed and dried out. Dense stands of dry Italian ryegrass burn readily.' 'An additional detrimental effect of postfire seeding is that dense stands of Italian ryegrass burn readily ... '

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/fire_ecology.html

4.09

Italian ryegrass is a shade intolerant species.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

4.1

'Italian ryegrass grows in a wide range of soil types except for excessively drained or very poorly drained soils.'

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

4.11

Probably not - not a vine.

Wagner, W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii. University of Hawaii at Press. Honolulu.

4.12

No evidence

5.01

5.02

'Annual ryegrass is a winter annual grass found throughout the United States that may reach 3 ft in height.'

http://216.239.53.100/search?q=cache:kpysAlEetbsC:www.ppws.vt.edu/
scott/weed_id/ryegrass.PDF+Lolium+multiflorum+&hl=en&ie=UTF-8

5.03

5.04

6.01

Seeding of Italian ryegrass is often followed by seeding with perennial species the following year.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/value_and_use.html

6.02

In western Oregon, where most of the Italian ryegrass seed is produced, seed remains dormant in the cold, wet soil during winter and then volunteers in crops when fields are plowed.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/value_and_use.html

6.03

(1) 'Natural hybrids of Italian ryegrass and perennial ryegrass are interfertile.' (2) 'Hybridization: known to hybridize with several other species of Lolium. In Australia, hybrids with L. perenne (occurring throughout Australia except the A.C.T. and N.T.) and L. rigidum (occurring throughout Australia) are recognized. '

(1)http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/introductory.html (2)http://biodiversity.uno.edu/delta/pooid/www/descr214.htmhttp://biodiversity.uno.edu/delta/pooid/www/descr214.htm

6.04

It is self-incompatible

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

6.05

wind-pollinated grass

http://www.umweltbundesamt.org/fpdf-k/2103.pdf

6.06

Italian ryegrass regenerates by seed.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

6.07

Annuals or short lived perennials.

Wagner, W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii. University of Hawaii at Press. Honolulu.

7.01

the flower spikelets carry long bristles called `awns'.

http://www.ulstermuseum.org.uk/flora/default.htm?item=2529

7.02

A high-quality forage grass, regarding both the nutritious value and the digestibility.

http://www.umweltbundesamt.org/fpdf-k/2103.pdf

7.03

As a contaminant of hay

7.04

Seeds are mainly dispersed by wind or by animals.

http://www.umweltbundesamt.org/fpdf-k/2103.pdf

7.05

No evidence

7.06

No evidence

7.07

the flower spikelets carry long bristles called `awns'.

http://www.ulstermuseum.org.uk/flora/default.htm?item=2529

7.08

[consumption by cattle] Seeds are mainly dispersed by wind or by animals. A high-quality forage grass, regarding both the nutritious value and the digestibility.

http://www.umweltbundesamt.org/fpdf-k/2103.pdf

8.01

(1)Probably not - seeds relatively large - 'caryopsis brown, dorsally compressed, obovoid to ellipsoid, 3 -4 mm long.' (2)Each spikelet consists of 5 to 24 florets, (3)5-38 spikelets per inflorescence, 10-20 seeds per spikelet.

(1)Wagner, W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii. University of Hawaii at Press. Honolulu. (2)http://www.umweltbundesamt.org/fpdf-k/2103.pdf (3)http://forages.orst.edu/topics/species/output.cfm?PlantID=1

8.02

'Italian ryegrass is unlikely to form a substantial seedbank because seeds germinate readily. ... Where high soil temperatures are associated with intermediate soil moisture, viable seed is depleted through germination. However, seed dormancy is induced when seeds are buried in cold, wet soil. Dormancy in buried seed did not reach maximum levels until 120 days after burial. The longevity of buried Italian ryegrass seed is not known. Thompson and Grime [60] place Italian ryegrass in the transient seedbank category; seeds are present only for a short time in the summer and fall.'

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/botanical_and_ecological_characteristics.html

8.03

'Results indicate that standard Roundup and Gramoxone treatments containing atrazine and Bladex continue to be very efficacious.'

http://216.239.53.100/search?q=cache:kpysAlEetbsC:www.ppws.vt.edu/scott/
weed_id/ryegrass.PDF+Lolium+multiflorum+&hl=en&ie=UTF-8

8.04

Fire probably kills Italian ryegrass. Seeds may survive fire.

http://www.fs.fed.us/database/feis/plants/graminoid/lolmul/fire_effects.html

8.05

Don’t know.