This could point to a way of reducing the use of glyphosate, which is going to eventually cause resistance in grass and weed species as it has overseas, Foundation for Arable Research (FAR) maize project manager Mike Parker said.
“It’s especially a problem along paddock boundaries, under fence lines, roadsides and around sheds where the same spray is regularly used.”
Two ryegrasses are known to be resistant to glyphosate in New Zealand, Lollium multiflorum and L. perenne.
“It’s about thinking how to do things a bit differently,” he said.
“Hopefully in time the need to put on these herbicides should be less and less.”
FAR hosted a field day at Geoffrey Peake’s dairy farm near Te Awamutu in December to showcase a two-year maize trial using perimeter weed suppressive plantings around the maize crop. He milks 275 cows on 75ha producing 1800kg milksolids (MS)/ha. He grows 6ha maize annually in the same effluent paddock.
He had started to notice yellow bristle grass along the edges of the maize paddock and was keen to take part in the trial to get on top of the problem early. The research involves a 1.5m perimeter strip of different species planted around the maize crop, to find which suppress weeds best. Those used included a Nui ryegrass and white clover mix, lucerne, red clover, white clover, prairie grass and Feast II ryegrass.
They weren’t sprayed out between the maize harvest and annual grass crops during the last two years.
Peake said he was impressed with the trial so far and more than happy with his maize crops despite the potential loss of two outside rows, reducing drymatter by four tonnes.
“Four tonnes of feed could cost me about 320kg (MS) or at the current payout of $8.30/kgMS about $2500,” he said.
The benefits, however, included a saving of $450 in planting costs, a premium for a clean crop which doesn’t have yellow bristle grass and feed immediately available when the maize crop is harvested. There was also a better opportunity to control weeds around the maize crop because of easier access for spray application.
The first rows of the maize grew better without the weeds hampering growth because there was more light and moisture available. The clovers also fixed nitrogen further aiding maize growth, Parker said.
Different herbicides were used to eliminate weeds, establish the suppressive species and monitor the herbicide reactions. The biggest impact was on the red clover which suffered temporary leaf scorching while the white clover was fine.
The lucerne, prairie grass and white clover crops gave very good cover to suppress weeds.
