Publicação on-line; 25 ref.; 3 tables; 3 illus.; Summary (En)

ABSTRACT
Background: Inconsistent control of Barnyardgrass has been reported
repeatedly by farmers in major rice growing areas of Iran and Turkey.
Objective: Thus, a greenhouse study was conducted to investigate the
resistance of Barnyardgrass to acetyl CoA carboxylase (cyhalofop-butyl)
and acetolactate synthase (penoxsulam, bispyribac-sodium) inhibiting
herbicides.
Methods: The seeds were sown in pots in a greenhouse and after
screening, were sprayed with various rates of cyhalofop-butyl, penoxsulam
and bispyribac-sodium herbicides at 3-4 leaf stage. Four weeks later, the
above ground biomass was cut, dried in an oven and weighted. The
results were then analyzed in the R software (drc package) using a four
or three parameter log-logistic function. All experiments were repeated
twice.
Results: While 30% of biotypes collected from Turkey were not controlled
by ACCase inhibitors at twice the recommended rates, no resistance was
observed in Iran’s samples. Only one biotype exhibited cross-resistant to
penoxsulam and bispyribac-sodium in Iran, which was due to consecutive
application of herbicides with modes of action similar to these herbicides.
In contrast, several Turkish biotypes showed cross-resistance as well as
multiple resistance to ACCase and ALS inhibitors.
Conclusions: The rapid expansion of herbicide resistance in both
countries indicate the necessity of adopting integrated weed management
practices to hinder the further evolution of resistance in future

Keywords:
dose-response
Echinochloa crus-galli
multiple-herbicide resistance
rice