False Pickerel Weed | Monochoria vaginalis (Burm.f.) C. Presl ex Kunth

California Pest Rating for
False Pickerel Weed | Monochoria vaginalis (Burm. f.) C. Presl ex Kunth
Commelinales: Pontederiaceae
Pest Rating: A |  Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

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.

Final Score:

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

 Uncertainty:

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.


References:

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.

CABI. 2018. Invasive Species Compendium. Wallingford, UK: CAB International. Accessed January 10, 2018. www.cabi.org/isc

Calflora. Accessed January 30, 2018. http://www.calflora.org

Consortium of California Herbaria. Accessed January 10, 2018 http://ucjeps.berkeley.edu/consortium/

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.

Oppenheimer, H. 2011. New Hawaiian plant records for 2009. Bishop Museum Occasional Papers. 110: 5–10.

Oraze, M.J., Grigarick, A.A., Lynch, J.H., and K.A. Smith. 1988. Spider fauna of flooded rice fields in northern California. Journal of Arachnology. 16: 331–337.

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.

United States Department of Agriculture. Natural Resources Conservation Service. Plants Database. Accessed January 10, 2018. https://plants.usda.gov

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


Author:

Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, plant.health[@]cdfa.ca.gov

Responsible Party:

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.


Comment Period:* CLOSED

1/31/18 – 3/17/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Comment Format:

♦  Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦  Posted comments will not be able to be viewed immediately.

♦  Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦  Comments may be edited prior to posting to ensure they are entirely germane.

♦  Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Pest Rating: A |  Proposed Seed Rating: R


Posted by ls

11 thoughts on “False Pickerel Weed | Monochoria vaginalis (Burm.f.) C. Presl ex Kunth”

  1. The comments contributed in response to the proposed pest rating of Monochoria vaginalis all recommend a lower rating and that Monochoria vaginalis not be added to the Prohibited Seed List. The points made in the comments fall into several general categories that I address below.

    1. The weed is easily controlled by commonly available herbicides. The fact that rice farmers do not generally complain about this species as one of the most pernicious rice weeds attests that it is controllable under current conditions. Nevertheless, the literature and the comments below indicate that targeted control is necessary to prevent production losses and weed proliferation. Therefore, it does indeed change practices to respond to its threat. In addition, although rice farmers have been managing this species for decades, few, if any, infestations have been eradicated. This indicates that it is a tenacious pest.
    2. The area where most California certified rice seed production occurs is generally infested with Monochoria vaginalis. Therefore, listing it on the Prohibited Seed list would decertify a large percentage of California rice seed. This is a real problem. Changing the recommended seed rating to R (restricted) would allow adding it to the Section 4500 list of noxious weeds. The presence of restricted weeds in a rice field does not cause loss of certification, if the weeds are actively managed. Changing this recommendation would remove the most serious objection to this Pest Rating Proposal. That said, Monochoria vaginalis is a federal noxious weed and is regulated by six other states. This has little significance as long as seed is distributed only in California; if this circumstance changes, it may become an issue. This would depend on the rules of the recipient and whether the weed seed can always be cleaned from rice seed adequately.
    3. It has been in California for decades and has not spread widely. The fact that it has been present in California for decades may or may not be relevant. Plants are somewhat different from insect pests in that it is well documented that, in some cases, they have a long lag phase before they truly ramp up their invasion. This means that time from first detection is much less informative for weeds than it is for insects and other pests. In addition, in the last two decades there have been fewer than ten weed samples from rice fields submitted to the CDFA Botany Lab for identification. The Consortium of California Herbaria contains records of about 100 collections in the same time frame. Still, we really know very little about the actual distribution of this (or any) rice field weed.
    4. Because it has not escaped and is constantly controlled, it poses no threat to the environment. Certainly to the extent that Monochoria vaginalis is controlled in agricultural settings it will reduce the extent to which it can invade natural habitats. Nevertheless, because of the long lag periods associated with several invasive weeds, we cannot be confident that the current system is adequate to prevent the escape of Monochoria vaginalis. The common confusion of this species with Heteranthera limosa contributes to our lack of understanding of the distribution of both taxa. It is notable that the only vouchered collection of Monochoria vaginalis outside of Butte County (in Tehama County) was later annotated as Heteranthera limosa. The paucity of specimens of this species may or may not reflect the true extent of its occurrence.
    5. Research on the management of this species would be halted by an A rating. Research on this plant would require a permit if it were to receive an A rating. If the researcher had adequate containment protocols, there is no reason that research could not continue on this species.

    After considering the Pest Risk Proposal and the associated comments, the following ratings are recommended:

    Rating; A
    Recommended Seed Rating: R

    Dean Kelch, Ph.D.
    Primary Botanist
    California Department of Food & Agriculture

  2. Comment submitted by:
    From: Luis A Espino
    Sent: Wednesday, March 21, 2018 12:30 PM
    To: Kelch, Dean@CDFA
    Subject: California Pest Rating Proposal for Monochoria vaginalis

    Dear Dean,

    I write to comment about the proposed classification of Monochoria vaginalis with a seed rating of “prohibited”. This seed rating would have severe consequences to the rice industry in California, specifically to seed production, and therefore I think a closer look to the current status of Monochoria as a weed of rice is warranted.

    As other commenters have stated, Monochoria has been present in the Biggs and Richvale areas of Butte County for at least 70 years. Since then, this weed has not expanded its range. There might have been some anecdotal reports of Monochoria being a present in other rice producing counties, but this was due to misidentification. Monochoria has blue flowers, and is similar in growth pattern to duck salad. Duck salad has a biotype with blue flowers, and therefore some growers were calling this biotype of duck salad Monochoria. This confusion, and the description of both duck salad and Monochoria, is documented in the 2007 report to the Rice Research Board by Albert Fischer, then weed scientist with UC Davis (http://www.carrb.com/07rpt/2007%20Fischer%20RP-1.pdf).

    As Rice Farm Advisor in Colusa, Glenn and Yolo counties, I have not run into any fields infested with Monochoria in these counties. Working in the rice industry, I am aware of production challenges rice growers face outside of my assigned counties; Monochoria has never been one. Since 2008, herbicide trials conducted at the Rice Experiment Station have demonstrated that Monochoria can be effectively controlled with registered herbicides (see the Weed Management reports to the board posted at http://www.carrb.com/AnnualRpts.html). A typical herbicide program in rice includes herbicides to control grasses and broadleaves. Broadleave herbicides currently in use in California are effective against Monochoria.

    All of this supports the conclusion that the pest dispersal potential and potential economic impact of Monochoria is low. Considering this, I hope CDFA would reconsider the proposed seed rating of this weed.

    Luis Espino
    Rice Farming Systems Advisor
    Colusa, Glenn and Yolo Counties

    County Director
    Colusa County
    University of California Cooperative Extension
    100 Sunrise Blvd., Suite E
    Colusa, CA 95932
    Office: 530-458-0578

  3. Comment submitted by:
    Fritz Durst
    Sent: Tuesday, March 20, 2018 11:56 AM
    To: Kelch, Dean@CDFA

    Dear Mr. Kelch:

    I am a rice seed producer in Yolo and Colusa Counties and I am responding to the possible listing of Monochoria Vaginalis as an A-rated noxious weed.  I do not believe that it should be listed as a Prohibited weed species.

    This weed has been in the Sacramento Valley for some time and I feel is not a threat to our industry.  We currently have herbicides such as Granite and Bolero that can easily control this species of noxious weed.  I don’t believe that it is as common as some people believe as it is easily confused with Purple Flower Duck Salad, which by the way is developing a resistance to some herbicides.  My two PCA’s have informed me that monochoria is more prevalent in the northern rice growing areas than in the central and southern areas.

    Listing monochoria at this time would have a significant impact on the rice industry.  We would loose our current year’s foundation M-206 seed which would have a longer term impact on the industry.  Our industry has been trying to encourage growers to not keep their own seed for the purpose of controlling weedy rice.  One of the benefits that we are offering to growers to steer them from retaining their own seed is genetic purity.  Eliminating this year’s Foundation seed will reduce that benefit in years 2019 & 2020.

    Please consider NOT listing monochoria vaginalis as an A-rated noxious weed.

    Thank you,

    Fritz Durst

  4. Comments submitted by:
    Rice Experiment Station
    P. 0. Box 306 • Biggs, California 95917-0306
    Telephone: 530-868-5481• Fax: 530-868-1730

    March 20, 2018

    TO: Dean G. Kelch, Primary Botanist
    FROM: Kent S. McKenzie, Director and Plant Breeder

    RE: Division of Plant Health’s Pest Rating and Proposal
    Monochoria vaginalis (False Pickerel Weed)

    The classification of Monochoria vaginalis as a category A pest by CDFA and a P seed rating is of serious concern to this organization and the California Rice Industry. I oppose this recommended rating for the following reasons:

    1. The production of certified classes of rice seed by the Rice Experiment Station (RES) and seed growers in the area. The Rice Experiment Station produces the foundation seed for more than 90% of California’s rice production. The presence of an A weed pest and a P seed rating would disqualify a seed field and threaten the foundation seed program at RES.

    2. Planting of certified classes of rice seed ensure the purity and quality of our California rice varieties at the production level and in the worldwide market place. Use of California grown certified seed has protected the California Rice Industry from the Liberty-Link GM contamination that occurred in the Southern US Rice Industry, which had total worldwide economic losses estimated at $735 M (E. Neal Blue Consulting, Ohio State University, 2007). Certified seed will be a tool used to protect the spread of weedy red rice, and beginning in 2019 all rice planted in California must be either certified seed or seed from a third party quality assurance program approved by the Certification Committee (Rice Certification Act Advisory Board).

    3. Research and development at the Rice Experiment Station will be impacted. RES provides gratis support to the University of California to conduct weed control, pest control, and agronomic rice research and these projects are funded in part by the grower funded California Rice Research Board. M vaginalis, as well as many other rice weeds, is present in the 16 acre weed control site at Hamilton Road. This allows the evaluation of herbicide and production practices to control rice weeds, including M vaginalis. The research there gives essential support to growers as well as the Agrochemical Industry in testing and developing improved herbicides. M vaginalis is also present at some locations on the headquarters property, but is of minor importance and controlled by registered herbicides and production practices. By necessity, RES tractors, tillage equipment, and harvest equipment are used though out the entire property. Cleaning or excluding them from these areas would not be feasible and could require abandoning those research activities.

    4. M vaginalis has been in the area for over 50 years and has not been a threat to rice production. There is no recent comprehensive study to show wide dispersal in California. Comments made by weed scientists from the UC and private industry and also rice pest control advisors indicate that it has not expanded widely, is not considered a major rice weed threat, and is controlled with registered rice herbicides. Until this month, I cannot find any documentation expressed to this organization concerning seed production and research activities in regards to M vaginalis by the California Crop Improvement Association, the Butte County Agricultural Commissioner’s Office, or CDFA. This all suggests that the initial potential concerns have not been realized after decades of time and are not valid.

    Specific Comments on Rating Scores

    1) Climate/Host Interaction
    After more than 50 years is has not become a significant weed of concern in rice. Existing evidence
    is that it has remained in very limited areas. Low (1)

    2) Host Range
    Per the 50 year of history above, it has not expanded widely in California. It can be found on field margins in rice fields but has not spread. Moderate (2)

    3) Pest Dispersal Potential
    Although it produces many seeds, as many rice weeds do, they apparently remain in the field maturing after drainage, they are low in the canopy (avoiding harvest) and California does not export rice seed. Low (1)

    4) Economic Impact
    Major economic impact on yield, production costs, market loss, or normal cultural practices is not indicated.
    A&B- Economic impact on yield no more than other current rice weeds, control measures are available and effective, no supporting evidence from commercial reporting.
    C- Not found in processed rice and rice varieties and seed are restricted from export from California.
    D- Not an issue with current production practices of rice in California. Low (1)

    5) Environmental Impact
    A, B, and C- After more 50 years, the experience and observations are that M vaginalis has not moved to any major extent from the rice fields where it has been observed and controlled with registered pesticides. It does not seem to be adapted to vernal pool habitats as an area of concern. Moderate (2)

  5. Comment submitted by:
    Cherokee Farms GP

    Via U.S. Post

    March 21, 2018

    Mr. Dean G. Kelch, Primary Botanist
    California Department of Food and Agriculture
    1220 N Street
    Sacramento, CA 95814

    Re: Monochoria Vaginalis Proposed Listing

    Mr. Kelch:

    Cherokee Farms GP is our family rice farming operation that I have been operating since 1971. Two of our fields border the California Rice Experiment Station on its south border. In the years referenced in the Proposed Listing in which M. vaginalis was found in Butte County (1954- 1991) this plant has not been found in our fields. Accordingly, I would give the plant a low score to number 5) Post Entry Distribution. Similarly, because there has been little dispersal over a 70 year period, it is unlikely to establish throughout California, even though the state has suitable hosts and climate. This category also should be rated Low (1) as should the Host Range. Because of the lack of spread dispersal over this time period, logic says that the Host Range could be no more than Medium(2).

    This pest is easily controlled by products readily available and currently in use in California rice fields. Therefore, I believe your High (3) score for environmental impact is incorrect; it should be Low (1). Similarly, while the pest could lower crop yield if uncontrolled, control costs would be minimal and normal cultural practices would not be affected. The report’s conclusions that the pest could lower crop value, trigger the loss of markets or interference with the delivery or supply of water (the pest grows in shallow water, not in ditches) are simply incorrect and show a lack of understanding of how rice is farmed. The economic impact should Low (1), and the total score should similarly be Low.

    Cherokee Farms GP is also a seed grower. Changing the rating of this pest from a “Q” to “A” will devastate California’s seed program. The new California Seed Law will in 2019 require all seed planted in the State to be certified or have a similar Quality Assurance rating. Certified seed must be free of noxious weeds. A zero tolerance requirement for the presence of this pest could easily mean that California has no or certainly an inadequate supply of seed, which truly would mean the economic and environmental impact of an “A” rating would be High (3).

    Please reconsider your conclusion.

    Cherokee Farms GP Tim Kelleher, President
    Cherokee Farms, Inc. a partner

  6. Comment submitted by:

    Butte County Rice Growers Association
    P.O. Box 128
    Richvale, CA 95974 (530) 882-4261

    3/20/2018

    Dear Mr. Kelch,

    I am writing in response to the recent call for comment regarding the California Pest Rating Proposal for False Pickerel Weed/Monochoria vaginalis. I have worked as a weed researcher and pest control advisor in California rice production for over 25 years. I am very familiar with M. vaginalis as it has been included in many studies I have conducted. I strongly encourage CDFA to reevaluate the proposal to change the current rating from Q to A because I believe the change could unnecessarily produce a negative impact on the California rice industry.

    Below are my comments for your consideration:

    1) Climate/Host Interaction:

    2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

    Comment: I believe M. vaginalis should carry a Low host range rating. M. vaginalis is susceptible to most of our currently registered rice herbicides and is not competitive with established rice. It is not likely to proliferate as it rarely survives conventional treatment of the broadleaf weed spectrum in rice. This greatly reduces the amount of favorable ecological areas for growth of M. vaginalis. It has remained in limited distribution in California for over 60 years for these reasons.

    3) Pest Dispersal Potential: M. 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.

    Comment: Lowering the High dispersal risk rating should be considered because seed development potential is greatly reduced by common control measures practiced in conventional rice production. Conditions for perennial development are poor due to cultivation of fields in preparation of planting. Additionally, seed ripening is late in the rice season which does not encourage dispersal.

    4) Economic Impact: M. vaginalis is reported to cause significant yield losses in rice (CABI, 2018).

    I believe economic impact risk is Low for the following reasons:

    Economic Impact: A, B, C, D, G

    A. The pest could lower crop yield.

    Comment: Monochoria is not likely to cause significant yield reduction unless it is left untreated in an unusually high population. Rice producers are not likely to allow competitive populations to occur.

    B. The pest could lower crop value (includes increasing crop production costs).

    Comment: Monochoria is well controlled using current weed control practices. Increased cost for additional control measures should not be necessary.

    C. The pest could trigger the loss of markets (includes quarantines).

    Comment: Practically, it shouldn’t be a problem in paddy or milled rice at all. It might be a problem in seed rice if we grew seed rice outside of California which we do not as seed of our current varieties are prohibited from export and are not well adapted to other rice growing regions.

    D. The pest could negatively change normal cultural practices.

    Comment: Existing practices have controlled M. vaginalis adequately for many years. Additional or different cultural practices would have minimal impact. It is not considered a problem weed with respect to its competiveness with rice.

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

    Comment: Efficient water delivery and drainage systems are critical to rice production. There are currently many weeds that proliferate in these systems. For that reason growers and water districts maintain vegetation control measures to insure that supply and drain ditches are clean and unimpeded. Therefore the risk of interference by M. vaginalis is limited.

    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.

    Comment: A, B, C I believe it is wrong to assume that M. vaginalis is a serious threat to sensitive ecosystems without any instances of significant spread to wild habitats such as vernal pools since it was identified in California over 60 years ago.

    D. The pest could trigger additional official or private treatment programs.

    Comment: Additional private or official measures would not be necessary as current practices adequately control M. vaginalis.

    M. vaginalis is not likely to have a significant impact environmentally for many of the previously stated reasons. It is not a tough to control weed and it does not have known resistant phenotypes. There are many existing remedies were it to begin to spread.

    Rice Production in California is an intensely managed system. As you know, there are many professionals, including Agronomists, Pest Control Advisors, UC professionals, Crop Consultants and Growers, that monitor and maintain the system to minimize pests and minimize environmental impact. That effort has been successful and will continue. I would strongly recommend that the proposed “prohibited” seed rating be reevaluated and a “restricted” seed rating be imposed if it is determined that a seed rating is necessary.

    Sincerely,

    Joe Desmond, PCA, CCA Research Manager
    Butte County Rice Growers Association
    Richvale, CA 95974
    530-682-6695

  7. Comment submitted by:
    Dana Dickey
    Executive Director, Rice Research Board

    March 20, 2018

    Dean Kelch
    Lisa Serrano
    CDFA Plant Health and Pest Prevention Services Division
    Sacramento, CA 95814

    RE: Monochoria vaginalis California Pest Rating Proposal

    Dear Staff,

    After reading about the Rating Proposal for Monochoria vaginalis, I would submit the following reasons for opposing the listing.

    RE: Monochoria vaginalis California Pest Rating Proposal

    Dear Staff,

    After reading about the Rating Proposal for Monochoria vaginalis, I would submit the following reasons for opposing the listing.

    1) Climate/ Host Interaction: Monochoria vaginalis is susceptible to most of our current broadleaf herbicides. It is controlled by these herbicides that are applied early in the growing season. Monochoria vaginalis is not competitive with established rice once the canopy closes and it is controlled prior to canopy closure.

    2) Host Range: If rice fields are considered the host environment, then the conventional treatment of the broadleaf weed spectrum should prevent proliferation.

    3) Pest Dispersal Potential: The fact that Monochoria vaginalis can produce a large number of seeds per plant is a testimony to the effectiveness of the rice industry weed control program. If these plants were producing tens of thousands of seeds per plant, Monochoria vaginalis would be spread over thousands of acres in a short time. Yet the plant has only been established in a small Butte county area for over 60 years – and shows no particular signs of expansion.

    4) Economic Impact: California rice enjoys the highest yields in the U.S. and perhaps the world. If Monochoria vaginalis were causing significant yield losses, then grower complaints to the RRB would be significant. Instead, Butte county has very high yields within the State because of the control specified in item 1 above. If the Monochoria vaginalis is left uncontrolled there would be the potential for economic loss; however, by failing to control broadleaf weeds generally, Monochoria vaginalis, would be a minor concern compared to the yield loss from other broadleaf weeds.

    5) Economic Scoring:

    a) Regarding crop yield and lowering crop value, the Rice Research Board will spend over 3.3 million dollars on research in 2018. Monochoria vaginalis is of no significant concern. It shows up on a list of weeds that herbicides are tested against along with other more noxious weeds. This list of weeds is tested against various herbicides for degree of control. Mulitple materials show 99-100% control of Monochoria vaginalis. (Annual Report of the Rice Research Board, 2017; Weed Management in Rice; Kassim Al-Khatib, UC Davis). Many weed species concern the rice industry, but this is not one of them.

    b) Regarding the loss of markets, if Monochoria vaginalis is already globally widespread, why would a country close itself off to our rice? The California rice industry already ships rice into some of the most challenging markets in the world (Japan, etc.) where a vast number of elements are examined. These markets have not raised a concern over this weed.

    c) Since standard weed control practices control broadleaf weeds, including Monochoria vaginalis, how would this weed change normal cultural practices?

    d) This weed would not interfere with the delivery of water any more than existing weeds. Again, our research shows that existing herbicides control Monochoria vaginalis very well.

    6) Environmental Impact: Monochoria vaginalis has been established in a small area for over 60 years. If over that time it has not expanded its area significantly, what forces are going to cause expansion? The California rice industry has experienced several weed resistance issues (i.e. Londax in the 1990’s) that spread at alarming rates. In contrast, the Monochoria vaginalis “threat” has not expanded significantly. It seems overly optimistic to assume that 60 years of history will suddenly change and the problem will spread to locations for which it is clearly poorly suited.

    In conclusion, since the problem is confined to a small rice producing area and the rice industry has a standard practice means of controlling Monochoria vaginalis and other weeds within its class, the listing of this weed does not seem justified. It has been established for over 60 years without significant expansion. Changing the Pest Rating will not change this weeds territory or expansion, but it will impact the rice industries ability to produce seed for itself. The rice industry performs large amounts of research and breeding within this area and produces foundation seed used by >90% of the industry, yet the weed has not been spread through this means either. I hope you will reconsider this Pest Rating.

    Sincerely,
    Dana Dickey
    Executive Director, Rice Research Board

  8. Comment submitted by:
    Tim Johnson
    President/CEO
    California Rice

    March 20, 2018

    Mr. Dean G. Kelch, Primary Botanist
    California Department of Food and Agriculture
    1220 N Street
    Sacramento, CA 95814

    Dear Mr. Kelch:

    RE: California Rice Commission comments on proposed listing of False Pickerel Weed, Monochoria Vaginalis (Burm.F.) C. Pres ex Kunth From Pest Rating Q to Proposed Pest Rating A and Proposed Seed Rating P

    The California Rice Commission (CRC) is a statutory organization representing the entirety of the California rice industry consisting of 2,500 rice farmers and 40 marketers (CDFA FAC 71000-71138). We represent the California rice industry on regulatory issues for pesticides, air and water quality, conservation programs and public education. California is the second largest rice producing state in the United States, growing mostly Japonica medium grain on an average of 500,000 acres annually. In California, rice is one of the top 20 commodities, and the seventh largest commodity export, which contributes more than $5 billion annually to the state’s economy.

    False Pickerel Weed (Monochoria vaginalis), is an introduced pest on the Federal Noxious Weed list with the symbol MOVA and covering the entire state of California. Per the CDFA website, Monochoria vaginalis has a current pest rating of Q. Monochoria vaginalis has been a controllable weed in the California rice producing areas though the current rating.

    The CDFA Pest Proposals and Final Ratings provides the following:

    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.
    – Medium (2) may be able to establish in a larger but limited part of California.

    CRC Response: Monochoria vaginalis is manageable and does not proliferate as it
    rarely survives conventional treatment of broadleaf weed spectrum in rice.

    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.
    – High (3) has a wide host range.

    CRC Response: With rice fields the host, Monochoria vaginalis will not proliferate as it is controlled through treatment of broadleaf weeds in rice.

    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:

    – High (3) has both high reproduction and dispersal potential.

    CRC Response: True of almost every weed found in California.

    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)
    – High (3) causes 3 or more of these impacts.

    CRC Response: Any untreated weed could lower crop yield. Monochoria vaginalis is treatable. The only way Monochoria vaginalis could lower crop value, or trigger losses in markets is if it changes from “Q” to “A” rating. Over 99 percent of all rice grown in California is found in eight contiguous counties (Butte, Colusa, Glenn, Placer, Sacramento, Sutter, Yolo and Yuba). Monochoria vaginalis has been established for 70 years, so no negative changes to normal cultural practices are necessary. Monochoria vaginalis does not interfere with delivery or supply of water for agricultural uses as would be the case with any weed left untreated in rice fields.

    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)
    – 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

    CRC Response: As stated previously, Monochoria vaginalis has been established in California for 70 years. The rice industry would have experienced the negative environmental impact by this date. Monochoria vaginalis is controlled through conventional herbicide programs, so no threat to lowering biodiversity, disrupting natural communities, or changing ecosystem processes. These factors would only apply if Monochoria vaginalis was uncontrollable. Monochoria vaginalis does not directly affect threatened or endangered species, or their habitats, as it is a controllable weed with herbicides that do not proposes threats. Monochoria vaginalis could trigger additional official or private treatment programs if the rating is changed from “Q” to “A”. Monochoria vaginalis is found in rice fields and does not spread to home and urban gardening or ornamental settings.

    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.
    –Low (-1) Pest has a localized distribution in California or is established in one suitable climate/host area (region).

    CRC Response: The CRC agrees with this assessment, which contradicts the assumptions from rating criteria found in all previously listed Consequences of Introduction (1 to 5).

    From the CDFA Encycloweedia: Weed Ratings website:

    To advise commissioners as to the Department’s policy regarding any pest action.

    Definition of “Q
    An organism or disorder suspected to be of economic or environmental detriment, but whose status is uncertain because of incomplete identification or inadequate information.

    Definition of “A
    A pest of known economic or environmental detriment and is either not known to be established in California or it is present in a limited distribution that allows for the possibility of eradication or successful containment. A-rated pests are prohibited from entering the state because, by virtue of their rating, they have been placed on the of Plant Health and Pest Prevention Services Director’s list of organisms “detrimental to agriculture” in accordance with the FAC Sections 5261 and 6461. The only exception is for organisms accompanied by an approved CDFA or USDA live organism permit for contained exhibit or research purposes. If found entering or established in the state, A-rated pests are subject to state (or commissioner when acting as a state agent) enforced action involving eradication, quarantine regulation, containment, rejection, or other holding action.

    Summary and Recommendations
    The CRC strongly believes the Monochoria vaginalis provides no negative impact to the California rice industry. Changing the rating from “Q” to “A” would be devastating by creating the negative contribution effecting economic, trade and environmental impacts to the California rice industry. The assumptions for changing the ratings are inaccurate, so we offer the opportunity to provide additional input on California rice cultural practices.

    We suggest an extension of the comment period to allow the rice industry experts and researches time for more extensive responses. The CRC requests a meeting with your office and the rice industry prior to any final determination. Through our collaboration, we have a “Rice Team” consisting of the CRC, UC Davis, UC Cooperative Extension, Rice Research Board, Rice Experiment Station, rice growers and other rice industry representatives. Please contact me with questions for additional information and clarification on the comments provided in this letter.

    Sincerely,

    Tim Johnson
    President/CEO

  9. Comment submitted by:
    Kassim Al-Khatib
    Melvin Androus Endowed Professor for Weed Science
    University of California, Davis

    March 19, 2018

    To whom it may concern

    I am writing regarding identifying Monochoria vaginalis as a noxious weed with a prohibited seed rating that would mandate a zero tolerance policy for this weed in all rice seed fields. I am professor/specialist of weed science in rice at the University of California, Davis. I have been conducting weed science and outreach activity for more than 30 years. My research program currently focused on weed management in rice. I have conducted research on biology and control of Monochoria vaginalis.

    Monochoria vaginalis has been documented to be present and common in the area north of Biggs for decades. Monochoria vaginalis is an aquatic weed that does not compete well with rice plants and is predominantly present on the edges of fields where there is little competition for resources. In addition, Monochoria vaginalis requires a shallow water environment and blooms in mid-to-late summer in California. Monochoria vaginalis environmental and ecological growth requirements do not make this weed fit in different ecological systems. Furthermore, infestation with Monochoria vaginalis in California rice fields is not sever compare to other weedy species and that in part due to smaller Monochoria vaginalis seed size than rice seed which allows cleaned out seeds used for planting.

    We have included this weed in our research program for many years. Our main object in Monochoria vaginalis research is to identify weed management practices including herbicides to control this weed. Our research showed that at Monochoria vaginalis is effectively controlled with standard herbicide treatments. Our research showed that bensulfuron, halosulfuron, orthosulfamuron, bispyribac, penoxsulam, and imazosulfuron give effectively control Monochoria vaginalis. In addition, Monochoria vaginalis has not developed resistance to any of these herbicides.

    I understand that current proposed text gives Monochoria vaginalis a total rating of 13 out of 15 points. Some of the evaluations criteria should be reconsidered given the fact that some of these criteria against this weed are not accurate. I would score Monochoria vaginalis as having a final score of 7 out of 15. I do not think that mandate of zero tolerance policy for this weed in all rice seed fields is wise or needed.

    Sincerely,

    Kassim Al-Khatib
    Melvin Androus Endowed Professor for Weed Science
    University of California, Davis

  10. Dear CDFA,
    I am a weed scientist that has been working in rice in California since I started as a PhD student in 2012. I am currently a Rice Advisor with the University of California Cooperative Extension. In regards to the proposal to rate Monochoria vaginalis as a class “A” weed and a class “P” seed pest, I would advise to reduce the seed rating to “restricted”.

    As a weed scientist, I think the potential for this weed to spread and contaminate other fields or non-agricultural areas is low. The California Consortium of Herbarium have submissions from only 2 counties, Butte and Tehama, with the Butte samples dating back to as early as 1954. The most recent samples were collected in the 1990’s. The majority of the samples were collected from around the Rice Experiment Station, in Biggs. The Rice Experiment Station in Biggs produces the majority of rice seed for the 200,000 ha of rice grown in California. Since the 1950’s, M. vaginalis has remained in just a few fields in Butte County and has not spread throughout the other rice-growing counties in California, in spite of the fact that foundation rice seed is produced in the infested fields.

    As a weed scientist, I can say with some confidence that since it has not spread in approximately 70 years, this would be an indication that its potential for invasiveness in the California environment is low. Likewise, since it has not been seen in other parts of the United States, it is unlikely that rice seed from California would be a means by which this pest would spread.

    M. vaginalis is completely controlled by many registered rice herbicides. Furthermore, no instances of herbicide resistance have been recorded. The weed is therefore easy to control. Many of the broadleaf weeds of rice also end up being shaded out by the rice itself once the canopy closes, so M. vaginalis is unlikely to produce a lot of seed, even in organic fields.

    Again, due to its limited distribution and the fact that it has remained relatively immobile for 70 years, I would reduce the seed rating from “prohibited” to “restricted”.

    Respectfully,
    Whitney Brim-DeForest, M.S., PhD
    University of California Cooperative Extension Rice Advisor

  11. I am writing on behalf of the California Crop Improvement Association (CCIA) as this regulatory rating change will substantially impact the seed certification and quality assurance programs for rice seed production in California. The CCIA is the official seed certification agency in California as identified in the California Seed Law (see Code of California Regulations, Title 3, Division 4, Chapter 5, Subchapter 3. Article 4 §3875(a)). It should be noted that the requirements for rice seed production in California are higher than the minimum requirements outlined in the California Seed Law as all rice seed production is subject to third party inspection for compliance to field and seed quality standards. The Marketing Order regulating all rice production in California requires that (beginning in 2019) all rice planted in California must be either certified seed or seed from a third party quality assurance program approved by the Certification Committee (Rice Certification Act Advisory Board) (see Code of California Regulations, Title 3, Division 4, Chapter 2, Subchapter 5. §2852.5 – see https://www.cdfa.ca.gov/mkt/pdf/AdoptedText-RiceIdentityPres.pdf).

    Both certified seed production standards and quality assurance standards state the following:
    “Fields must be free of any prohibited noxious weeds. Restricted noxious weeds, and common weeds difficult to separate must be controlled. Prohibited and Restricted noxious weeds are listed in the California Seed Law/CA Code of Regulations/Sections 3854 and 3855. See California Seed Law – Prohibited and Restricted Noxious Weed List. All fields must be free of weedy/red rice, the weedy red grain type of Oryza sativa.” (http://ccia.ucdavis.edu/Crop_Standards_pages/Rice/ & http://ccia.ucdavis.edu/Quality_Assurance_Programs/Rice_Seed_Quality_Assurance_Program/)

    By identifying Monochoria vaginalis as a noxious weed with a prohibited seed rating, this would mandate a zero tolerance policy for this weed in all rice seed fields.
    M. vaginalis has been documented to be present and common in the area north of Biggs for decades. Furthermore, this weed has been included in herbicide trials over many years so there is documented information on its control in relation to other weeds present in rice production. Research has shown that M. vaginalis is effectively controlled through standard herbicide treatments (see http://wric.ucdavis.edu/PDFs/2017%20RICE%20FIELD%20DAY_Rice%20weed%20control%20handout.pdf). There are no herbicide resistant populations of M. vaginalis (see http://rice.ucanr.edu/files/229838.pdf).

    I would strongly recommend that the proposed “prohibited” seed rating be reevaluated and a “restricted” seed rating be imposed if it is determined that a seed rating is necessary. All rice production is subject to the Marketing Order and the aforementioned standards for a ‘restricted’ seed rating would effect a zero tolerance in all conditioned seed lots (see previously cited CCIA links). By providing a restricted seed rating, this would also allow for tolerances during field production as opposed to complete rejection of seed production and the associated serious economic impacts of such rejections. Tolerances in the field should be allowed in the case of M. vaginalis given that this weed is normally restricted to field edges and can therefore be avoided during harvest (i.e. seed from the field edges can be harvested for paddy rice instead of seed rice). Also, given that the seed size is significantly smaller than rice seed, it can be cleaned out using the proper seed conditioning equipment.

    The current proposed pest rating gives M. vaginalis a total rating of 13 out of 15 points. Some of the evaluations for these points should be reconsidered given the available information. Consider reevaluating the following points:

    *Claim:
    “2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable…. – High (3) has a wide host range.”

    Argument against claim:
    This rating should be a Low (1) or Medium (2), given that this is an aquatic weed and will only be potentially present in spring and summer shallow-flooded freshwater aquatic natural ecosystems, and only potentially present in rice and wild rice agricultural ecosystems.

    *Claim:
    “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.”

    Argument against claims B, C, D and G:
    B: As previously cited, M. vaginalis is a weed that is controlled through standard and routine herbicide treatment programs. Unlike many common weeds in rice systems, this weed does not have herbicide resistance populations and is effectively controlled.
    C: Seed rice is not exported to regions outside California. This being the case, there is no potential for loss of export markets. It should be noted that it is illegal to export the predominant rice varieties (i.e. protected varieties produced by the Rice Experiment Station) developed in California (see slide 9, http://rice.ucanr.edu/files/217622.pdf).
    D: As previously cited, this weed is controlled through standard and normal herbicide treatments.
    G: M. vaginalis is an aquatic weed that does not compete well with rice and is predominantly present on the edges of fields where there is little competition for resources.

    *Claim:
    “5) Environmental Impact:…
    …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.”

    Argument against claims A, B, C
    The lifecycle of M. vaginalis would make this weed unfit for infestation of vernal pool ecosystems. M. vaginalis requires a shallow water environment and blooms in mid-to-late summer in California (see Aquatic and Riparian Weeds of the West, DiTomaso and Healy, pg. 346). Vernal pools dry down in the spring and are very dry throughout the summer, making this environment unsuitable for the reproductive phase of M. vaginalis, and therefore not threatening the many rare species in this ecosystem (see https://www.wildlife.ca.gov/Conservation/Plants/Vernal-Pools).

    Using the pest rating scale, I would score M. vaginalis as having a final score of 7 out of 15.

    Respectfully,
    Timothy Blank
    California Crop Improvement Association

Comments are closed.