Thursday, October 4, 2012

Thailand: IRRI offers first workshop on herbicide-resistant rice

IRRI conducted the first herbicide-resistant rice (HRR) workshop for Asia in Bangkok, Thailand, on 19-20 September 2012.

HRR is a cultivar of rice that is resistant to a particular herbicide or herbicides that would otherwise damage the rice crop. Herbicides can be sprayed on the resistant rice cultivar and destroy weeds without affecting the rice.

To date, three herbicide-resistant rice systems have been developed: imidazolinone-, glufosinate-, and glyphosate-resistant. Glufosinate- and glyphosate-resistant rice cultivars were developed through transgenic technologies. Imidazolinone-resistant rice cultivars (Clearfield®) are non-transgenic.

Clearfield rice was first commercialized in Asia in Malaysia in 2010 and may be introduced soon in other Asian countries.

HRR is typically used where weedy rice infests rice fields, as weedy rice is not controlled by selective herbicides. Weedy rice is a problem in Asia, particularly in Sri Lanka, Vietnam, the Philippines, Thailand, Malaysia, and parts of India.

The HRR technology is effective and simple, but comes with the risk of the herbicide-resistant weedy rice evolving via gene flow or herbicide selection pressure.

While HRR may help solve weed control problems in rice in the short term, without good stewardship its widespread use may become a threat to the sustainability of the Asian rice industry.

IRRI organized this workshop on HRR with these aims:
  • make farmers aware of options on the use of HRR in rice production systems
  • identify potential problems related to HRR
  • record lessons learned from the introduction of HRR in Latin America and North America
  • identify steps to be taken to minimize any negative effects of HRR
Twenty-six participants attended from IRRI, Bangladesh, Brazil, Costa Rica, India, Malaysia, Philippines, Sri Lanka, Thailand, USA, Vietnam, and BASF.

For more information, please contact Bhagirath Chauhan, weed scientist at IRRI (

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