Jointed bulrush | Pest Rating Proposals and Final Ratings

California Pest Rating for

Jointed bulrush | Schoenoplectus articulatus (L.) Palla

Family: Cyperaceae

**Synonym: Scirpus articulatus L.**

Pest Rating: D | Proposed Seed Rating: N/A

PEST RATING PROFILE

Initiating Event:

This plant recently has been detected in dried flower arrangements coming from India to California.

History & Status:

Jointed bulrush is an annual or perennial grass-like plant that has the ability to grow in both flooded and moist, upland conditions; this makes it a widespread wetland plant throughout the paleotropics. It has also been noted as a weed in rice. Seedling emergence can occur in both saturated and aerobic-moist soil, demonstrating that this plant does not require a saturated soil and that it can emerge from a moist soil. Jointed bulrush is not yet known from California, but it is considered a weed of rice in India where it is native. It can be distinguished from California native species of Schoenoplectus by the spikelets being clustered near the base of the stem, rather than near the apex.

Official Control: None in California. It is used as an element in dried plant arrangments from India and Southeast Asia.

California Distribution: Jointed bulrush does not occur in California at this time.

California Interceptions: One detection (PDR #19TP06465285) attached to a shipment of a dried plant arrangement from India that came through Virginia.

The threat that Jointed bulrush 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: 1

– 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 low (1), as the plant occurs in tropical wetlands only. Our rice fields are in colder areas and the subtropical area of California has little of the potential habitat.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

– 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: Evaluate the natural and artificial dispersal potential of the pest. Score: 2

– 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 Medium (2). The plant produces via numerous seeds and spreads in water. This might limit the speed of its spread. It could also be spread via the pathway of untreated fruiting stems being included in dried floral arrangements. Effective treatment of such plant material before entry into the U.S. would prevent any such accidental introduction.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 2

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).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

– 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 Medium (2) as the plant can lower crop yields and force changes in cultural practices where it is established.

5) Environmental Impact: Evaluate the environmental impact of the pest on California using the criteria below.

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. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score: 2

– 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 Medium (2) as, once established, it could conceivably invade the water systems of southern California and disrupt natural wetland communities.

Consequences of Introduction to California for Jointed bulrush:

Add up the total score and include it here. (10)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: 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. Score: -0. Not yet established in CA.

–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

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (12)

Uncertainty:

Uncertainty is relatively high. Jointed bulrush is not naturalized in California yet, It’s current weediness seems restricted to rice fields in tropical areas. Nevertheless, other wetland weeds have surprised us by invading areas colder than their native range. Any detection of Jointed bulrush in the ambient environment in CA should prompt a reevaluation of its potential risk.

Conclusion and Rating Justification:

A potential weed in wet areas of the tropics, this plant is unlikely to establish in CA. This plant deserves a D rating as it is unlikely to be invasive in CA, although it is a rice field weed in its native range of India. Due to the paucity of references to its weediness, Jointed bulrush does not seem to be as destructive as some other rice field weeds.

References:

Baskin, C. C. & J. M. Baskin. 2001. Chapter 11: Plants with Specialized life-cycles or habitats in Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination. Academic Press (Elsevier). San Diego, California.

Bopal, B. 1991. Ecology and management of aquatic vegetation in the Indian subcontinent. Kluwer International Press. Dordrecht, Netherlands.

Moody, K. 1989. Weeds Reported in Rice in South and Southeast Asia. International Rice Research Institute. Manila, Philippines.

Shanker, C. 2013. Flora from Cuttack for ID. Efloraofindia Internet site accessed on 5/15/2016:

https://groups.google.com/forum/?hl=en-GB#!topic/indiantreepix/UQk-KIWRfEo

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.