Herbicide Resistant Weeds

GROUP D/22 RESISTANT DOTTED DUCKWEED (Landoltia punctata)
USA: Florida

Saturday, July 31, 2010

What's on this page

Dotted Duckweed

1.	Introduction
2.	Level of Infestation
3.	Quick Statistics
4.	Notes about this biotype
5.	Academic Aspects
6.	R Dotted Duckweed Globally
7.	Fact Sheets and Literature
8.	Contributing Weed Scientists
9.	Acknowledgements
10.	Where to now?

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

Introduction

Level of Infestation

Dotted Duckweed (Landoltia punctata) is a dicot weed in the Lemnaceae family. In Florida this weed first evolved resistance to Group D/22 herbicides in 2001 and infests aquatic. Group D/22 herbicides are known as Bipyridiliums (Photosystem-I-electron diversion). Research has shown that these particular biotypes are resistant to diquat, and paraquat and they may be cross-resistant to other Group D/22 herbicides.

Local weed scientists estimate that Group D/22 resistant Dotted Duckweed in Florida infests 1 site and the number of sites are decreasing. They also estimate that there are 1-5 acres infested with Group D/22 resistant Dotted Duckweed and the area infested is decreasing.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their mode of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS ( last updated May 24, 2005 )
Common Name	Dotted Duckweed
Species	Landoltia punctata
Group	Bipyridiliums (D/22)
Herbicides	diquat, and paraquat
Location	USA, Florida
Year	2001
Situation(s)	aquatic
Sites	1
Acres Infested	1-5
Contributors	Tyler Koschnick
Input Data	Edit this Case \| Add New Case of Resistance \| Add Note

ACADEMIC ASPECTS

Confirmation Tests

Laboratory trials comparing a known susceptible Dotted Duckweed biotype with this Dotted Duckweed biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

The genetic basis of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the genetic inheritance of this biotype please update the database.

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group D/22 resistant Dotted Duckweed from Florida please update the database.

Edit Case | Add Note | Add Article | Add New Case | Help

HERBICIDE RESISTANT DOTTED DUCKWEED GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	USA (Florida)	2001	1	1-5	Bipyridiliums (D/22)

FACT SHEETS AND OTHER LITERATURE	Format
At Present there are no articles on this case of resistance. Please help by adding an article.
Add New Article

CONTRIBUTING WEED SCIENTISTS

TYLER KOSCHNICK	Edit
Visiting Assistant Professor University of Florida Agronomy Center for Aquatic Plants 7922 NW 71st St Gainesville, 32653, Florida USA Email Tyler Koschnick

Acknowledgements

Where to now?

The Herbicide Resistance Action Committee, The North American Herbicide Resistance Action Committee, the Weed Science Society of America, and weed scientists in Florida have been instrumental in providing you this information. Particular thanks is given to Tyler Koschnick for providing detailed information.

1.	Resistant Weeds Globally
2.	Resistant Weeds in the USA
3.	Herbicides
4.	Weed Researchers
5.	Resistant weeds in Florida
6.	Search this site