INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE
Italian Thistle (Carduus pycnocephalus) is a dicot weed in the Asteraceae family. In New Zealand this weed first evolved resistance to Group 4 (Legacy O) herbicides in 1997 and infests Pastures. Group 4 (Legacy O) herbicides are known as Auxin Mimics
). Research has shown that these particular biotypes are resistant to 2,4-D, MCPA, and MCPB and they may be cross-resistant to other Group 4 (Legacy O) 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.
HRAC Group 4 (Legacy O)
|2,4-D, MCPA, and MCPB
|Contributors - (Alphabetically)
|Field, and Greenhouse trials comparing a known susceptible Italian Thistle biotype with this Italian Thistle biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.
|Genetic studies on HRAC Group 4 resistant Italian Thistle 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
|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.
|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 4 (Legacy O) resistant Italian Thistle from New Zealand please update the database.
|Associate Professor in Weed Science
School of Agriculture
Private Bag 11-222
Palmerston North, 4442, Manawatu
Email Kerry Harrington
Web : Web Site Link
|Drag a column header and drop it here to group by that column
2,4-D, MCPA, and MCPB
( HRAC Group 4 (Legacy O)
PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I. The International Herbicide-Resistant Weed Database. Online.
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