Goatsrue (Galega officinalis)

California Pest Rating for

Goatsrue (Galega officinalis)

Pest Rating: A | Seed Rating: P

PEST RATING PROFILE

Initiating Event:

There is a recent detection of goatsrue found growing in Eastern Mendocino County. This is the first detection of this species occurring spontaneously in California.

History & Status:

Background: Goatsrue is a deep-rooted perennial, sprouting each spring from a crown and taproot reaching 2 to 6 feet tall by late summer. Plants may have up to 20 hollow stems. The first seedling leaves are large, oval and dark green. The mature leaves are alternate, odd-pinnate with six to ten pairs of leaflets. The white and bluish to purplish pea-like blossoms are borne in terminal or axially racemes. A single plant may produce upwards of 15,000 pods. Goatsrue seeds drop on the ground when mature and may be spread by water, equipment, or animals. Goatsrue seeds typically remain dormant until scarified and may remain viable for ten or more years.
Goatsrue is a USDA federally listed noxious weed. A member of the legume family, goatsrue was introduced into Utah in 1891 as a potential forage crop. Goatsrue now occupies in excess of 60 square miles in Cache, County, Utah. Within this area, goatsrue infests cropland, fence lines, pastures, roadsides, waterways, and wet, marshy areas. The plant’s stems and leaves contain a poisonous alkaloid, galegin, which renders the plant unpalatable to livestock, and toxic in large quantities. It is particularly lethal to sheep.
Goatsrue is controlled by herbicides such as 2,4-D plus Dicamba or glyphosate, although the crowns of treated plants may remain viable up to seven years unless retreated or removed. New herbicide chemistry may improve success rates. Tillage in row crops can suppress regrowth and break up the seed production cycle. Utah weed control personnel indicate that goats rue control is very difficult, requiring significant amounts of time and labor. Their experience reinforces the concept that early detection and rapid control is the most effective means of preventing large-scale establishment.

Official Control: Goatsrue is listed as a noxious weed in Alabama, Florida, Massachusetts, Minnesota,Nevada, North Carolina, Oregon, Pennsylvania, South Carolina, Vermont, and Washington.

Worldwide Distribution: Goatsrue is native to the Middle East; it viewed as naturalized throughout most of Europe, western Asia, and western Pakistan.

U.S. Distribution: In the U.S. goatsrue is found in 12 states, including CA, OR, WA, UT, & CO. The largest infestations occur in Cache County, Utah, where it was first introduced to the U.S. Populations in states other than CA and UT may be historic.
California Distribution: Currently, Goatsrue is known from Cow Mountain in Eastern Mendocino and Western Lake Counties.

The risk goatsrue would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 2

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.

Risk is medium (2) as illustrated by the localized range of the plant in states where it occurs. Goatsrue would be expected to colonize riparian areas, pond margins, wetlands, roadside ditches, irrigation canal banks, and moist forest edges.

2) Pest Host Range: Score: 3

Evaluate the host range of the pest:

– Low (1) has a very limited host range
– Medium (2) has a moderate host range
– High (3) has a wide host range

Risk is high (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

3) Pest Dispersal Potential: Score: 3

Evaluate the dispersal potential of the pest:

– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.

Risk is High (3) as the plant spreads via water flow and human dispersal from vehicles. It also has ben detected as a seed contaminant in commercial seed lots.

4) Economic Impact: Score: 3

Evaluate the economic impact of the pest to California using these criteria:

A. The pest could lower crop yield
B. The pest could lower crop value (includes increasing crop production costs)
C. The pest could trigger the loss of markets (includes quarantines by other states or countries)
D. The pest could negatively change normal production cultural practices

– Low (1) causes 0 or 1 of these impacts
– Medium (2) causes 2 of these impacts
– High (3) causes 3 or more of these impacts

Risk is high (3) as goatsrue lowers range value and productivity and requires expensive treatments to control. As goatsrue is a federal noxious weed, there is a chance that goatsrue would trigger limitation of interstate shipment of hay or other crops from where it occurs.

5) Environmental Impact:

Evaluate the environmental impact of the pest on California using the following criteria:

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes
B. The pest could directly affect threatened or endangered species
C. The pest could impact threatened or endangered species by disrupting critical habitats
D. The pest could trigger additional official or private treatment programs
E. Significantly impacting cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact: Score: 3

– Low (1) causes none of the above to occur
– Medium (2) causes one of the above to occur
– High (3) causes two or more of the above to occur

Risk is High (3) in California, as goatsrue is an aggressive invader of marginal wetlands. As such, it displaces native plant species in these important habitats. Species outcompeted and excluded potentially include such state and federal endangered plants as white sedge, Thomkin’s sedge, Delta eryngo, Bogg’s Lake hedge hyssop, western lily, Gambell’s watercress, and Calistoga popcornflower. Potential effects on endangered wildlife include breeding habitat modification, and food disruption (either directly from food plant exclusion, or indirectly via insect prey reduction). Potentially affected species include the Point Arena mountain beaver, red-legged frog, yellow-legged frog, and California tiger salamander.

Consequences of Introduction to California for Goatsrue:
Rating (Score):

Add up the total score and include it here

– Low = 5-8 points
– Medium = 9-12 points
– High = 13-15 points

Total points based on above criteria, which does not take into account the pathogen’s distribution in California: High (14).

6) Post Entry Distribution and Survey Information: Goatsrue has been found in in 1 locality in California; This may have spread from seed spread via a vehicle and/or cultivation. It receives a Low (-1) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

-Not established (0) Pest never detected in California, or known only from incursions.
-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (13)

Uncertainty:

This plant has just entered California, but it is spreading quickly via riparian corridors. It is not known how far its spread will extend, but the uncertainty is low that it will be invasive. Riparian habitat represents a small percentage of habitat in California, but it is widespread throughout the state and is disproportionally important due to its high water availability and high woody plant cover.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above: Proposed Rating: based on the score listed above the pest is a high risk. This justifies an “A” rating. As the plant is limited to one small areas, as far as is known, prompt and effective action would have a significant effect on the future impacts of this species.

Literature

Evans, J. O. & M. L. Ashcroft 1982. Goatsrue. Utah Agr. Exp. Stat. Res. Report.

Barrett, R. 2013. Oregon Department of Agriculture Plant Pest Risk Assessment for Goatsrue, Galega officinalis. Accessed 6/12/2015: http://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/PlantPestRiskAssessmentGoatsrue2013.pdf

Oldham, M, C. V. Ransom, M. H. Ralphs, and D. R. Gardner. 2011.
Galegine Content in Goatsrue (Galega officinalis) Varies by Plant Part and Phenological Growth Stage. Weed Science 59: 349-352.

USDA Plants, Galega officinalis. Acessed 6/12/2015:
http://plants.usda.gov/core/profile?symbol=GAOF

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.