Barnyardgrass resistance to quinclorac in paddy rice in Santa Catarina State

Abstract

Barnyardgrass (Echinochloa spp.) infestation is very high and results in significant yield losses in
paddy rice in Santa Catarina State. The objective of this study was to evaluate quinclorac resistance of Echinochloa spp. ecotypes in rice fields and to test the susceptibility of these populations to herbicides bispyribac-sodium and
cyhalofop-butyl. Three barnyardgrass populations were evaluated: ECH 33, ECH 37 and ECH 38, compared to a resistant (ECH 13) and a susceptible (ECH 17) ecotype. The experiment was carried-out in a greenhouse. Herbicide treatments were: quinclorac, cyhalofop-butyl and bispyribac-sodium. The ecotypes ECH 38 and ECH 13 are resistant
to quinclorac, but ECH 17, ECH 33 and ECH 37 are susceptible. Ecotypes ECH 38 and ECH 13, resistant to
quinclorac, are controlled by cyhalofop-butyl and bispyribac-sodium.