Annual ryegrass resistance to glyphosate herbicide has been documented in four NSW orchards and one in SA.
With glyphosate resistance on the increase in Australia, Crop Care has investigated annual ryegrass control by herbicides with different modes of action to glyphosate (Group M).
According to Crop Care horticulture business manager Kerrie Mackay, effective control of glyphosate-resistant annual ryegrass was obtained with Alliance (Groups L & Q), and with a combination of Shirquat (Group L) plus Stomp (Group D).
“Stomp provided effective pre-emergent control of resistant ryegrass, with continued control for three to four months after application,” Kerrie said.
“Alliance also provided good control of capeweed, prickly lettuce, sowthistle and medic, as well as resistant ryegrass.”
Kerrie said effective strategies for controlling resistant ryegrass included rotating herbicides from different mode-of-action groups, and minimising resistance spread by preventing annual ryegrass from setting seed.
“We also advise that if you notice single plants or patches of plants surviving a glyphosate application, that you submit surviving weeds for resistance testing.”
For contact details, see Tree Fruit May 2013
