Published on 22/10/2026
Dr Lauren Jones, UPL Regional Manager Central South Island, says forage brassicas are a hugely important winter crop, contributing 5-20% of feed in Canterbury alone.
“But weed pressure can result in yield losses of up to 60%.”
She recommends a three-pronged attack.
“While all actives have their particular strengths; the combination of three products with four actives — Merit, Monarch, and Major — give you really good weed control pre-emergence and they’re compatible.
Brassicas are also important in Southland. UPL Regional Manager Otago and Southland Greg McIntyre says a big investment goes into getting them right, and they require heavy inputs.
He says it’s also vital to monitor the paddock and consider its history.
“It can be two weeks from a potentially good crop to disaster. If not controlled early, then salvaging crops post-emergence can turn into a nightmare.”
Like Jones, he emphasises looking to the future of the paddock and consulting field reps or agronomists.
“You don’t want weeds dumping seeds that will impact the next rotations. Farmers always have to be looking a couple of years’ ahead.
“It’s not just the current season’s forage brassica crops that are at risk. Weed seedbanks can build up quickly in the soil. That threatens future crops and long-term production outcomes.”
The power of the three herbicides combined is firmly grounded in science.
Merit (alachlor, Group 15) controls a range of certain annual broadleaf and grassweeds in forage brassicas. Proven and effective, Merit extends the weed spectrum in a pre-emergence application.
Major (clomazone, Group 13) is a residual pre-emergence herbicide controlling a wide range of annual broadleaf and grassweeds in forage brassica crops. It provides outstanding control of problem weeds such as shepherd’s purse, chickweed and cleavers.
Monarch (clopyralid and picloram, Group 4) is a specially formulated herbicide for pre-emergence and post-emergence weed control and treads the balance between crop safety, efficacy, and affordability.