International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
HRAC GROUP 5 (LEGACY C1 C2) RESISTANT VELVETLEAF
(Abutilon theophrasti)


PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)

United States, Maryland
INTRODUCTION VELVETLEAF
Velvetleaf (Abutilon theophrasti) is a dicot weed in the Malvaceae family.  In Maryland this weed first evolved resistance to Group 5 (Legacy C1 C2) herbicides in 1984 and infests Corn (maize), and Cropland.   Group 5 (Legacy C1 C2) herbicides are known as PSII inhibitors - Serine 264 Binders (Inhbition of Photosynthesis at PSll - Serine 264 Binders ).  Research has shown that these particular biotypes are resistant to atrazine and they may be cross-resistant to other Group 5 (Legacy C1 C2) herbicides.

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

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QUIK STATS (last updated Sep 15, 2000 )

Common NameVelvetleaf
SpeciesAbutilon theophrasti
GroupPSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
Herbicidesatrazine
LocationUnited States, Maryland
Year1984
Situation(s)Corn (maize), and Cropland
Contributors - (Alphabetically)Ronald Ritter 
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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Velvetleaf biotype with this Velvetleaf 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

Genetic studies on HRAC Group 5 resistant Velvetleaf have not been reported to the site.  There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature
 
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 5 (Legacy C1 C2) resistant Velvetleaf from Maryland please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

RONALD RITTER
Professor
University Of Maryland
Plant Science and Landscape Architecture
1118 H. J. Patterson Hall
College Park, 20742 , Maryland
United States
Email Ronald Ritter
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Maryland have been instrumental in providing you this information. Particular thanks is given to Ronald Ritter for providing detailed information.
Herbicide Resistant Velvetleaf Globally
(Abutilon theophrasti)
Herbicide Resistant Velvetleaf Globally
(Abutilon theophrasti)
Drag a column header and drop it here to group by that column
Herbicide Resistant Velvetleaf Globally
(Abutilon theophrasti)
#CountryFirstYearSituationActive IngredientsSite of Action
1 United States (Maryland) United StatesMaryland1984 Corn (maize), and Cropland atrazine 45 PSII inhibitors - Serine 264 Binders (C1 C2/5)
1Abutilon theophrastiVelvetleaf425
2 United States (Wisconsin) United StatesWisconsin1990 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders (C1 C2/5)
1Abutilon theophrastiVelvetleaf410
3 United States (Minnesota) United StatesMinnesota1991 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders (C1 C2/5)
1Abutilon theophrastiVelvetleaf244
4 United States (Michigan) United StatesMichigan2004 Corn (maize), Nurseries, and Soybean atrazine 45 PSII inhibitors - Serine 264 Binders (C1 C2/5)
1Abutilon theophrastiVelvetleaf5289
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Wednesday, December 8, 2021 .  Available  www.weedscience.org
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