1 May 2005 Resistance to ACCase-inhibiting herbicides in sprangletop (Leptochloa chinensis)
Chanya Maneechote, Somsak Samanwong, Xiao-Qi Zhang, Stephen B. Powles
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This study reports evolved resistance to fenoxaprop-P in a population of sprangletop from a rice field in Thailand (BLC1). After eight applications of fenoxaprop-P, the herbicide appeared no longer effective. To confirm herbicide resistance in the BLC1 population, three experiments were conducted. First, glasshouse experiments revealed that the BLC1 population survived 600 g ai ha−1 of fenoxaprop-P without visual injury. Second, the BLC1 population was treated with fenoxaprop-P and other acetyl coenzyme A carboxylase (ACCase)–inhibiting herbicides (quizalofop-P, cyhalofop-butyl, and profoxydim) under field conditions; BLC1 exhibited resistance to all of these herbicides. Third, seeds of susceptible SLC1 and resistant BLC1 were germinated on 0.6% (v/v) agar across a range of herbicide concentrations. The resistant BLC1 population exhibited 61-, 44-, 9- and 8-fold resistance to fenoxaprop-P, cyhalofop, quizalofop-P, and profoxydim, respectively, compared with a susceptible SLC1 population. At the enzyme level, ACCase from the resistant BLC1 exhibited 30, 24, 11, 4, and 5 times resistance to fenoxaprop, cyhalofop-butyl, haloxyfop, clethodim, and cycloxydim, respectively. The spectrum of resistance at the whole plant level correlated well with resistance at the ACCase level. Hence, the mechanism of resistance to ACCase-inhibiting herbicides in this biotype of sprangletop is a herbicide-resistant ACCase. The specific mutation(s) of the ACCase gene that endows resistance in this population remains to be investigated.

Nomenclature: Clethodim; cycloxydim; cyhalofop; fenoxaprop-P; haloxyfop; profoxydim; quizalofop-P; sprangletop, Leptochloa chinensis (L.) Nees LEPCH; rice, Oryza sativa L.

Chanya Maneechote, Somsak Samanwong, Xiao-Qi Zhang, and Stephen B. Powles "Resistance to ACCase-inhibiting herbicides in sprangletop (Leptochloa chinensis)," Weed Science 53(3), 290-295, (1 May 2005). https://doi.org/10.1614/WS-04-164R
Received: 12 September 2004; Accepted: 1 December 2004; Published: 1 May 2005
ACCase-inhibiting herbicides
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