DISTRIBUTION OF GLYPHOSATE-RESISTANT GOOSEGRASS (ELEUSINE INDICA) POPULATIONS AND AN ALTERNATIVE HERBICIDE (INDAZIFLAM) TO CONTROL THEM

Abstrak

Goosegrass (Eleusine indica) in rubber plantations in Rambutan Estate, PTPN III has been controlled by using glyphosate continuously for 28 years. It has recently been reported that glyphosate is no longer effective for controlling E.indica in the area. How large the area of glyphosate-resistant goosegrass in the Rambutan Estate and what alternative herbicide as control options can be implemented is never reported.  This study aims to determine the distribution of E. indica populations that have evolved to be resistant to glyphosate and the possibility of indaziflam as alternative herbicide to control glyphosate-resistant goosegrass population in the Estate. Seed samples from more than 50 plants in each population which had continuously been exposed to glyphosate for 28 years were collected from 14 different rubber plantation blocks. The fourteen putative glyphosate-resistant goosegrass populations were tested for glyphosate resistance along with sensitive population that was never sprayed with herbicides, for comparison, (collected from the Campus Universitas Sumatera Utara in Medan)).  Each population is planted as many as 12 plants per pot with three replicates.  Plants at 4- to 5- leaf stage were sprayed with glyphosate with a dose of 480 g a.i. per hectare. Each population is arranged in a complete randomized design. The results of spraying goosegrass collected from 14 different populations indicated that eight populations are "highly resistant" and six are "resistant" to glyphosate.  Thus, it was concluded that fourteen goosegrass populations at Rambutan Estate have developed resistance to glyphosate.  To determine the effectiveness one of indaziflam as alternative herbicide, one population of the goosegrass was applied with indaziflam (PRE) at doses of 50, 75, 100, 150 g a.i per hectare and a plot without control as a comparison. Indaziflam, at all the rates tried, effectively controlled the glyphosate-resistant population.

Keywords: Eleusine indica, distribution, glyphosate, goosegrass, resistance