California Pest Rating for
False Pickerel Weed | Monochoria vaginalis (Burm. f.) C. Presl ex Kunth
Pest Rating: A | Proposed Seed Rating: R
PEST RATING PROFILE
Monochoria vaginalis, a Federal Noxious Weed, is currently Q-rated. Seeds of this species were recently found in rice from California. A permanent pest rating proposal is required to support an official pest rating.
History & Status:
Background: Monochoria vaginalis is a shiny, green aquatic herb that grows to 20 inches tall. Leaf shape varies; sessile leaves are narrow and lanceolate in shape and measure up to 5 cm in length, whereas petiolate leaves are heart-shaped and measure up to 8 cm in length and 5 cm in width (Flora of North America). The flowers are light blue and often open under water (Eckert et al., 2012). The seeds are approximately 1 mm in length and are oblong with longitudinal ribs (Scher et al., 2015). They germinate discontinuously, which makes this plant difficult to control (CABI, 2018). Monochoria vaginalis is found in rice fields, stagnant/slow areas of rivers, ponds, and other wet habitats at low elevations (Guofang and Horn, 2000; Smith, 1979). In constantly flooded conditions, it grows as a perennial (Strand, 2013). Even as an annual, however, it appears that it may require continuously flooded conditions that last long enough to allow germination, development, and fruiting to take place (Kunii and Okibe, 1999). Monochoria vaginalis is reported to be a serious weed in rice fields in Asia (Barrett and Seaman; 1980; CABI, 2018). It is currently a common weed at the Rice Experiment Station at Biggs, California (Al-Khatib et al., 2017). Weeds at this station were reported to severely impact rice yield, but the amount of yield reduction attributable to M. vaginalis is not known (Fischer, 2014). Monochoria vaginalis is used as a vegetable and medicine in Asia (CABI, 2018; Guofang and Horn, 2000).
Worldwide Distribution: Monochoria vaginalis is native to Asia and western Australia. It has been reported to occur in Australia, Bhutan, China, Cambodia, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Russia, Sri Lanka, Thailand, and Vietnam. It has also been reported from Fiji, Central America, South America, Mexico, and the United States (California and Hawaii). The records from the United States and some of the other localities (including Fiji) represent introductions (Aston; CABI, 2018; Gonzalez et al., 1977; Guofang and Horn, 2000; Horn and McClintock, 2012; Oppenheimer, 2011; Pacific Island Ecosystems at Risk, 2008; Smith, 1979).
Monochoria vaginalis has been reported to occur in “natural ponds” in India, at stream edges and in swamps and mud-pools in Australia, and in shallow, ephemeral (dry for half of the year) ponds in Cambodia (Aston; Maxwell, 2009; Meena and Rout, 2016). Thus, this plant may pose a threat to vernal pools in California.
Official Control: Monochoria vaginalis (along with M. hastata) is listed as a Federal Noxious Weed and the genus Monochoria is listed as a regulated plant pest by the United States. Monochoria vaginalis is also regulated by the following states: Alabama (Class A noxious weed), California (Q-rated quarantine plant), Florida (Class 1 prohibited aquatic plant), Massachusetts (prohibited plant), North Carolina (Class A noxious weed), Oregon (quarantine plant), South Carolina (invasive aquatic plant), and Vermont (Class A noxious weed) (United States Department of Agriculture). It is also on the South African list of prohibited alien plants (Invasive Species South Africa, 2016).
California Distribution: There are 11 collections of M. vaginalis from the Biggs area in Butte County (from 1954 to 1991), mostly from the vicinity of the rice experiment station, (Consortium of California Herbaria). As of 1980, it was apparently restricted to the Biggs area and was one of the most abundant weeds in the rice fields there (Barrett and Seaman, 1980). There is one collection from Tehama County (Consortium of California Herbaria), a disjunct of 55 miles. The apparently slow spread of this weed in California may be related to seed dispersal in this species occurring after the pre-harvest drainage of rice fields (Strand, 2013).
California Interceptions: Monochoria vaginalis has not been intercepted in California.
The risk Monochoria vaginalis would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Monochoria vaginalis appears to tolerate a wide range of climates, based on the range of localities it has become established in (including Butte County, California). It appears likely that it could become established in many areas in California, but limited to areas where there is sufficient water. Therefore, Monochoria vaginalis receives a Medium (2) in this category.
Evaluate if the pest would have suitable hosts and climate to establish in California.
– 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.
2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.
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.
3) Pest Dispersal Potential: Monochoria vaginalis can reproduce via seeds as well as through rhizomes. This weed can produce an average of 29,700 seeds per plant (Kunii and Okibe, 1999). Therefore, it receives a High (3) in this category.
Evaluate the natural and artificial dispersal potential of the pest. Score:
– 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.
4) Economic Impact: Monochoria vaginalis is reported to cause significant yield losses in rice (CABI, 2018). If it spread into a larger portion of California, it could impact rice cultivation, including lowering yield and increasing production costs. As a Federal Noxious Weed, the presence of M. vaginalis could lead to the loss of markets and change normal cultural practices in rice cultivation. In addition, as an aquatic weed, M. vaginalis could interfere with the supply of water for agricultural purposes. It receives a High (3) in this category.
Evaluate the economic impact of the pest to California using the criteria below. Score:
Economic Impact: A, B, C, D, G
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.
Economic Impact Score: High (3)
– 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.
5) Environmental Impact: Monochoria vaginalis has been reported to occur in a variety of habitats in Asia, including streams, swamps, and ponds/pools, including ephemeral ponds in Cambodia that are dry for half of the year. Therefore, this plant may be capable of invading these habitats in California. Vernal pools are a particularly threatened habitat in California; it is estimated that only 3–10% of these pools remain on the Pacific Coast (Gerhardt and Collinge, 2003). If M. vaginalis invades vernal pools, riparian areas, or other similar habitats in California, it could compete with native plants, threatening both them as well as wildlife dependent on the native plants. Rare plants that could be threatened include Boggs Lake hedge hyssop (Gratiola heterosepala H. Mason & Bacigal.), delta tule pea (Lathyrus jepsonii E. Green var. jepsonii), prickly spiralgrass (Tuctoria mucronata (Crampton) Reeder), and false venus’ looking glass (Legenere limosa (E. Greene) McVaugh) (Calflora). In addition, if M. vaginalis became a more widespread pest in rice fields, it could trigger additional treatment programs. Therefore, it receives a High (3) in this category.
Evaluate the environmental impact of the pest on California using the criteria below.
Environmental Impact: A, B, C, D
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:
Environmental Impact Score: High (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.
Consequences of Introduction to California for Monochoria vaginalis: High (14)
Add up the total score and include it here.
–Low = 5–8 points
–Medium = 9–12 points
-High = 13–15 points
6) Post Entry Distribution and Survey Information: Based on the available specimen records, within California, Monochoria vaginalis is presumed to be established only in Butte County. 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (13)
Monochoria vaginalis has been established in Butte County, California since the 1950s. There is one occurrence documented in Tehama County. It is not known to have spread significantly within or from this area. This could be an indication that this weed has limited invasive potential in California. In addition, although it is reportedly a common weed in rice in the vicinity of Biggs, California, little information is available on any impact that can be directly attributed to M. vaginalis there. Fuller and Barbe (1983) suggest that this weed is not able to become a significant problem in California rice because of the density of the rice plants in commercial operations in this state. Therefore, this weed may not have the potential to develop into a serious weed of rice in California.
If plants suspected to be Monochoria vaginalis are found in your area, please bring samples to the nearest Agricultural Commissioner office [https://www.cdfa.ca.gov/exec/county/countymap/] to be submitted to the Botany Lab for determination and voucher specimens in the herbarium of the California Department of Food and Agriculture (CDA).
Conclusion and Rating Justification:
Monochoria vaginalis is a Federal Noxious Weed that could potentially become a more widespread pest of rice in California, and it could also invade ecosystems including vernal pools and riparian areas. It is apparently restricted in distribution in California at the present time. For these reasons, an “A” weed rating and “P” seed rating is justified.
Al Khatib, K., Godar, A.S., Lee, M., Ceseski, A., McCauley, K.E., Stogsdill, J.R., Brim-DeForest, W., Linquist, B.A., Espino, L., and R.G. Mutters. 2017. Weed control in CA rice: Evaluation of new weed control tools. Rice Field Day. Wednesday, August 30, 2017. California Cooperative Rice Research Foundation, Inc., University of California, and United States Department of Agriculture.
Aston, H.I. Flora of Australia Online. Monochoria vaginalis. Accessed January 10, 2018. http://www.anbg.gov.au/abrs/online-resources/flora/stddisplay.xsql?pnid=57579
Barrett, S.C.H. and D.E. Seaman. 1980. The weed flora of Californian rice fields. Aquatic Botany. 9: 351–376.
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Eckert, J., Williams, J., Lundberg, J., and A. Fischer. 2012. Traits for field identification of Monochoria vaginalis and species of Heteranthera at different growth stages. Accessed January 25, 2018. http://wric.ucdavis.edu/events/archived_events/poster_Ducksalad_2012.pdf
Fischer, A. 2014. 2014 Annual Report (January 1, 2014 – December 31, 2014). Weed control in rice. California Rice Research Board. Accessed January 30, 2018 http://www.carrb.com/14rpt/2014%20Fischer%20RP1.pdf
Flora of North America. Accessed January 25, 2018. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200027397/
Fuller, T.C. and G.D. Barbe. 1981. Taxonomy and ecology of some rice weeds of California. pp. 60–65 in: Proceedings of the Ninth Asian-Pacific Weed Science Society Conference. National Science and Technology Authority and Philippine Tobacco Research and Training Center.
Gonzalez, J., Garcia, E., and M. Perdomo. 1977. Important rice weeds in Latin America.
Guofang, W. and C.N. Horn. 2000. Pontederiaceae. Flora of China. 24: 40–42.
Horn, C.C. and E. McClintock. 2012. Monochoria vaginalis, in Jepson Flora Project (eds.). Jepson eFlora. Accessed January 10, 2018. http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=33961
Invasive Species South Africa. 2016. Notice 4: List of prohibited alien species in terms of section 67(1). Government Gazette. 40166: 80–87.
Kunii, H. and K. Okibe. 1999. Comparative ecology of Monochoria korsakowii and M. vaginalis. Hydrobiologia. 415: 29–33.
Maxwell, J.F. 2009. Vegetation and vascular flora of the Mekong River, Kratie and Steung Treng Provinces, Cambodia. Maejo International Journal of Science and Technology. 3(1): 143–211.
Meena, T. and J. Rout. 2016. Macrophytes and their ecosystem services from natural ponds in Cachar district, Assam, India. Indian Journal of Traditional Knowledge. 15(4): 553–560.
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Pacific Island Ecosystems at Risk. 2016. Monochoria vaginalis. Accessed January 10, 2018. http://www.hear.org/pier/species/monochoria_vaginalis.htm
Scher, J. L., Walters, D.S., and A.J. Redford. 2015. Federal noxious weed disseminules of the U.S., Edition 2.2. California Department of Food and Agriculture, and USDA APHIS Identification Technology Program. Fort Collins, CO. Accessed January 25, 2018. http://idtools.org/id/fnw
Smith, A.C. 1979. Flora Vitiensis Nova. A New Flora of Fiji (Spermatophytes Only). Volume 1. Pacific Tropical Botanical Garden, Lawai, Kauai, Hawaii. 494 pp.
Strand, L. 2013. Integrated Pest Management for Rice – Third Edition. UCANR Publications. 98 pp.
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University of Guam and the Secretariat of the Pacific Community. 2014. https://www.doi.gov/sites/doi.gov/files/uploads/pac_regional_biosecurity_plan_for_micronesia_and_hawaii_volume_ii.pdf
Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, plant.health[@]cdfa.ca.gov
Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov.
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Pest Rating: A | Proposed Seed Rating: R
Posted by ls