Confirmation and control of glyphosate-resistant biotype of goosegrass (Eleusine indica L.). In Sumatran oil palm

Abstract

Glyphosate has been used as the main tool for weed control in an oil palm plantation for about four decades. In the last five years, in an oil palm plantation of PTP Nusantara III, a population of Eleusine indica was reported to have been difficult to control using glyphosate. The objectives of this study were first, to confirm whether the population of E. indica in the oil palm plantation has evolved resistance to glyphosate. Secondly, to evaluate post-emergent alternative herbicides, premixed 39.5% MSMA + 7.8% diuron, glufosinate ammonium, topramezone and glyphosate as a comparison, which were all of them applied at field rates of 1975 g + 390 g, 450 g, 41,25 g, and 1080 g a.i. ha−1, respectively. While pre-emergent herbicides, indaziflam, diuron, and flumoxiazin were applied 75, 1500, and 160 g a.i ha−1, respectively. The results showed that the suspected glyphosate-resistant E. indica population has been confirmed to have developed resistance to glyphosate. The population is highly resistant with level of resistance 28-fold of the susceptible population. No resistant plant was killed at the rate of 4320 g. a.e. ha−1 glyphosate (four-fold field rate for E. indica control) whereas the susceptible plant was killed 77,5%. Alternative herbicides tested effectively suppressed glyphosate-resistant E. indica population when applied at field rate. The alternative herbicides could be used to overcome glyphosate-resistance in the oil palm plantation.