{"id":985,"date":"2015-05-26T00:05:38","date_gmt":"2015-05-26T07:05:38","guid":{"rendered":"http:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=985"},"modified":"2022-04-29T15:23:46","modified_gmt":"2022-04-29T22:23:46","slug":"hydrocharis-morsus-ranae-l-european-frogbit","status":"publish","type":"post","link":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=985","title":{"rendered":"European Frogbit | Hydrocharis morsus-ranae L."},"content":{"rendered":"
California Pest Rating for<\/strong><\/h5>\n
European Frogbit | Hydrocharis morsus-ranae<\/em> L.<\/h5>\n
Pest\u00a0Rating: A | \u00a0Proposed\u00a0<\/strong>Seed Rating: P<\/strong><\/h5>\n
\n
PEST RATING PROFILE<\/strong><\/h5>\n
Initiating Event: <\/strong><\/h5>\n

This plant has been rated as \u201cA\u201d on the CDFA Plant Pest Rating list.<\/p>\n

History & Status:<\/strong><\/h5>\n

European frogbit is an annual herbaceous aquatic plant native to Europe. European frog-bit is generally free-floating but in situations where the vegetation is dense enough, the leaves may become emergent. It has been found in the Great Lakes Basin since the 1930s, but is now spreading into inland streams and lakes within the larger area surrounding the Great Lakes. It is considered invasive as it can displace native flora, possibly resulting in habitat impacts on native fauna by reducing oxygen content of bodies of water. European frogbit populations increase in size rapidly by vegetative reproduction and forms dense mats. These mats can infest irrigation canals.\u00a0 There are no effective controls for this species at this time. European frogbit was planted in ponds in Ottawa in 1932. It apparently escaped from these ponds; by 1939 it was found in the Rideau Canal and by 1967 it had spread into Lake Ontario, Lake Erie, and several localities in New York.<\/p>\n

Official Control:<\/strong><\/span> None in California.<\/p>\n

California Distribution:<\/strong>\u00a0<\/span> European frogbit does not occur in California at this time.<\/p>\n

California Interceptions: <\/strong><\/span>None.<\/p>\n

This threat European frogbit would pose to California is evaluated below.<\/p>\n

Consequences of Introduction:\u00a0<\/strong><\/h5>\n

1. \u00a0Climate\/Host Interaction:<\/strong> Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 2<\/strong><\/span><\/p>\n

\u2014Low (1)<\/strong> Not likely to establish in California; or likely to establish in very limited areas.<\/p>\n

\u2014Medium (2)<\/strong> may be able to establish in a larger but limited part of California.<\/span><\/p>\n

\u2014High (3)<\/strong> likely to establish a widespread distribution in California.<\/p>\n

Risk is medium (2)<\/span><\/strong>, as the plant could occur in wetlands such as the Delta.<\/em><\/p>\n

2. \u00a0Known Pest Host Range:<\/strong> Evaluate the host range of the pest.
\n\u00a0 \u00a0 \u00a0 Score: 3<\/span><\/strong><\/p>\n

\u2014Low (1)<\/strong> has a very limited host range.<\/p>\n

\u2014Medium (2)<\/strong> has a moderate host range.<\/p>\n

\u2014High (3)<\/strong> has a wide host range.<\/span><\/p>\n

Risk is high (3)<\/span><\/strong> as weeds do not require any one host, but grow wherever ecological conditions are favorable.<\/em><\/p>\n

3. \u00a0Pest Dispersal Potential:<\/strong> Evaluate the natural and artificial dispersal potential of the pest. Score: 3<\/strong><\/span><\/p>\n

\u2014Low (1)<\/strong> does not have high reproductive or dispersal potential.<\/p>\n

\u2014Medium (2)<\/strong> has either high reproductive or dispersal potential.<\/p>\n

\u2014<\/strong>High (3)<\/strong> has both high reproduction and dispersal potential.<\/span><\/p>\n

Risk is High (3).<\/span><\/strong> The plant produces via numerous seeds and overwintering turions, as well as spreading rapidly in water via vegetative growth.<\/em><\/p>\n

4 \u00a0Economic Impact<\/strong>: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 1<\/strong><\/span><\/p>\n

A. The pest could lower crop yield.
\nB. The pest could lower crop value (includes increasing crop production costs).
\nC. The pest could trigger the loss of markets (includes quarantines).
\nD. The pest could negatively change normal cultural practices.
\nE. The pest can vector, or is vectored, by another pestiferous organism.
\nF. The organism is injurious or poisonous to agriculturally important animals.
\nG. The organism can interfere with the delivery or supply of water for agricultural uses.<\/p>\n

\u2014Low (1)<\/strong> causes 0 or 1 of these impacts.<\/span><\/p>\n

\u2014Medium (2)<\/strong> causes 2 of these impacts.<\/p>\n

\u2014High (3)<\/strong> causes 3 or more of these impacts.<\/p>\n

Risk is low (1)<\/span> <\/strong>as the plant can impede irrigation.<\/em><\/p>\n

5. \u00a0Environmental Impact<\/strong>: Evaluate the environmental impact of the pest on California using the criteria below.<\/p>\n

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.
\nB. \u00a0The pest could directly affect threatened or endangered species.
\nC. \u00a0The pest could impact threatened or endangered species by disrupting critical habitats.
\nD. \u00a0The pest could trigger additional official or private treatment programs.
\nE. \u00a0Significantly impacting cultural practices, home\/urban gardening or ornamental plantings.<\/p>\n

Score the pest for Environmental Impact. Score: 3<\/span><\/strong><\/p>\n

\u2014Low (1)<\/strong> causes none of the above to occur.<\/p>\n

\u2014Medium (2)<\/strong> causes one of the above to occur.<\/p>\n

\u2014High (3)<\/strong> causes two or more of the above to occur.<\/span><\/p>\n

Risk is high (3)<\/strong><\/span> as the plant could invade the water systems of California, disrupt natural lake communities and potentially lower biodiversity by covering lake surfaces. \u00a0<\/em><\/p>\n

Consequences of Introduction to California for European frogbit:<\/strong><\/h5>\n

Add up the total score and include it here. (12)<\/strong><\/span><\/p>\n

\u2014Low<\/strong> = 5-8 points<\/p>\n

\u2014Medium<\/strong> = 9-12 points<\/span><\/p>\n

\u2014High<\/strong> = 13-15 points<\/p>\n

6. \u00a0Post Entry Distribution and Survey Information:<\/strong> 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.
\nScore: 0<\/strong><\/span><\/p>\n

\u2014Not established (0)<\/strong> Pest never detected in California, or known only from incursions.<\/span><\/p>\n

\u2014Low (-1)<\/strong> Pest has a localized distribution in California, or is established in one suitable climate\/host area (region).<\/p>\n

\u2014Medium (-2)<\/strong> Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate\/host areas.<\/p>\n

\u2014High (-3)<\/strong> Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate\/host areas.<\/p>\n

7. \u00a0The final score is the consequences of introduction score minus the post entry distribution and survey information score:<\/strong> (12) <\/strong><\/span><\/p>\n

Uncertainty: <\/strong><\/h5>\n

It\u2019s not here yet, but it is invasive in the Great Lakes Region.<\/p>\n

Conclusion and Rating Justification:<\/strong><\/h5>\n

A potentially weedy plant, especially in mountain lakes and cooler freshwater basins. Deserves an A rating, as it\u2019s so invasive in other states.<\/p>\n

References:<\/strong><\/h5>\n

Catling P.M., Dore W.G., 1982, Status and identification of Hydrocharis morsus-ranae<\/em>\u00a0 and Limnobium spongia<\/em>\u00a0 (Hydrocharitaceae ) in northeastern North America, Rhodora 84(840): 523-545.<\/p>\n

Flora of North America Editorial Committee, eds.\u00a0 1993+.\u00a0 Flora of North America North of Mexico.\u00a0 16+ vols.\u00a0 New York and Oxford.<\/p>\n

Global Invasive Species database: http:\/\/www.issg.org\/database\/species\/ecology.asp?si=862<\/a><\/p>\n

Responsible Party:<\/strong><\/h5>\n

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street,\u00a0Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.<\/p>\n

\n

Pest\u00a0Rating: A | \u00a0Proposed\u00a0<\/strong>Seed Rating: P<\/strong><\/h3>\n
\n

Posted by ls<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

California Pest Rating for European Frogbit | Hydrocharis morsus-ranae L. Pest\u00a0Rating: A | \u00a0Proposed\u00a0Seed Rating: P PEST RATING PROFILE Initiating Event: This plant has been rated as \u201cA\u201d on the CDFA Plant Pest Rating list. History & Status: European frogbit is an annual herbaceous aquatic plant native to Europe. European frog-bit is generally free-floating but … Continue reading European Frogbit | Hydrocharis morsus-ranae L.<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[7],"tags":[164,163,85],"class_list":["post-985","post","type-post","status-publish","format-standard","hentry","category-plants","tag-european-frogbit","tag-hydrocharis-morsus-ranae-l","tag-weeds"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5l8vQ-fT","jetpack-related-posts":[{"id":1958,"url":"https:\/\/blogs.cdfa.ca.gov\/Section3162\/?p=1958","url_meta":{"origin":985,"position":0},"title":"Weeds","author":"Admin","date":"May 13, 2016","format":false,"excerpt":"\u00a0 Weeds are simply an unwanted plant in the wrong place, at the right time.\u00a0 The weeds can directly and indirectly impact agricultural crops and are just as costly to the environment as any other unwanted species. 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