<b>HRAC Group 22</b> <font size='2'> (Legacy D) </font> resistant Youngia japonica from Japan

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 22 (LEGACY D) RESISTANT ASIATIC HAWKSBEARD
(Youngia japonica)

PS I Electron Diversion HRAC Group 22 (Legacy D)

Japan, Saitama, Ibaraki

INTRODUCTION		ASIATIC HAWKSBEARD
Asiatic Hawksbeard (Youngia japonica) is a dicot weed in the Asteraceae family. In Japan this weed first evolved resistance to Group 22 (Legacy D) herbicides in 1986 and infests Chesnut, Mulberry, and Roadsides. Group 22 (Legacy D) herbicides are known as PS I Electron Diversion (PSI Electron Diversion ). Research has shown that these particular biotypes are resistant to diquat, and paraquat and they may be cross-resistant to other Group 22 (Legacy D) 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.

QUIK STATS (last updated Dec 29, 2013 )
Common Name	Asiatic Hawksbeard
Species	Youngia japonica
Group	PS I Electron Diversion HRAC Group 22 (Legacy D)
Herbicides	diquat, and paraquat
Location	Japan, Saitama, Ibaraki
Year	1986
Situation(s)	Chesnut, Mulberry, and Roadsides
Contributors - (Alphabetically)	Yasutumi Imai, Kazuyuki Itoh, Satoshi Iwakami, and Akira Uchino
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Yasutumi Imai

Chestnut. Found in orchards and on riverbanks.

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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Asiatic Hawksbeard biotype with this Asiatic Hawksbeard 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 22 resistant Asiatic Hawksbeard 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 22 (Legacy D) resistant Asiatic Hawksbeard from Japan please update the database.

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CONTRIBUTING WEED SCIENTISTS

YASUTUMI IMAI

Dow Agrosciences Japan Dow Agrosciences 30500 Doe Circle Tokyo Japan

KAZUYUKI ITOH

Professor Kobe University Graduate School of Agricultural Science １-１ Rokkodaicho Kobe, 657-0013, Hyogo Japan Email Kazuyuki Itoh

SATOSHI IWAKAMI

Weed Scientist University of Tsukuba Faculty of Life and Environmental Sciences 1-1-1 Tennoudai Tsukuba, 305-8577, Ibaraki Japan Email Satoshi Iwakami

AKIRA UCHINO

Weed Scientist NARO Agricultural Research Center Faculty of Life and Environmental Sciences 3-1-1 Kannondai Tsukuba, 305-8666, Ibaraki Japan Email Akira Uchino

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Japan have been instrumental in providing you this information. Particular thanks is given to Yasutumi Imai, Kazuyuki Itoh, Satoshi Iwakami, and Akira Uchino for providing detailed information.

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Herbicide Resistant Asiatic Hawksbeard Globally
(Youngia japonica)

Country

FirstYear

Situation

Active Ingredients

Site of Action

China

2009

Unspecified

paraquat

PS I Electron Diversion ( HRAC Group 22 (Legacy D)

Japan

1986

Chesnut, Mulberry, and Roadsides

diquat, and paraquat

PS I Electron Diversion ( HRAC Group 22 (Legacy D)

Literature about Similar Cases

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Hanioka, Y.. 1989. Paraquat-resistant biotype of Youngia japonica (L.) DC. in mulberry fields in Saitama Prefecture. Weed Research (Tokyo) 34 : 163 - 168.

Leaf discs were taken from Y. japonica plants infesting mulberry fields in Saitama Prefecture and examined for their response to paraquat. leaf discs turned brown within 48 h on exposure to 1 p.p.m. of the herbicide. Discs from resistant biotypes, however, remained green even at concn of 10 p.p.m. This response was similar to that of Erigeron philadelphicus and Conyza canadensis plants resistant to paraquat. Y. japonica biotypes resistant to paraquat occurred on 34% of the mulberry field sites surveyed..

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Heap, I. The International Herbicide-Resistant Weed Database. Online. Friday, October 31, 2025 . Available www.weedscience.org Copyright © 1993- 2025 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.