Investigation of herbicides tolerated by Stevia rebaudiana crops

Abstract

A pot trial and two field trials evaluate the safetyto stevia plants of 25 herbicides, manyof which have been used for selective control in other Asteraceae crops. Pre-emergence herbicides that show potential for use in transplanted stevia include trifluralin, pendimethalin, oryzalin, bromacil, terbacil, linuron, methabenzthiazuron and alachlor. Post-emergence treatments that are tolerated reasonablywell bystevia include manyof the herbicides listed above plus clethodim, haloxyfop, propyzamide, thifensulfuron, flumetsulam and pyridate. Other postemergence herbicides that cause some crop damage but maymerit further research include bentazone, ethofumesate, MCPB, picolinafen, chloridazon and metribuzin. Terbacil and bromacil are the most effective herbicides for weed control, although some crop damage did occur. Controlling weeds through frequent hand-weeding allowed a 30-fold increase in stevia production in one trial, although the best result obtained byherbicides was a 19-fold increase using bromacil immediatelybefore transplanting stevia. © 2011 The Royal Society of New Zealand.