Thursday, 01 August 2019 13:55

Growing resistance worries arable sector

Written by  Nigel Malthus
Phil Rolston. Phil Rolston.

Initial results from the first national survey of herbicide resistance in arable farming have shown surprising resistance to glyphosate.

Foundation for Arable Research (FAR) senior research advisor Phil Rolston says nine of the 48 farms sampled – nearly 19% -- showed some resistance to glyphosate.

“We had some haloxyfop and pinoxaden resistance turning up, and that’s not a surprise because we’ve had farmers self-reporting some problems before. But finding glyphosate turning up on some of them was a surprise.”

The MBIE funded survey is a five year project in which FAR takes weed seed samples from farms randomly chosen from its database, and the samples are germinated then tested against a variety of herbicides by AgResearch Ruakura.

The survey started last summer on farms between the Waimakariri and Rakaia Rivers. FAR staff collected wild oat, brome and ryegrass plants from wheat and clover paddocks on the 48 farms, which represent about 20% of all cropping farms in the district. 

Resistance has so far been identified in ryegrass on 13 of the farms (27%). 

No resistance was found in any of the bromes and the results from the wild oat testing are not yet available.

The survey showed a wide range of resistance, Rolston says.

“Some farms showed [resistance in] more than 90% of the plants being tested, but others were down as low as 5%.”

The survey identified ryegrass resistant to Group A, Group B and Group G herbicides. Group A includes clethodim, haloxyfop-P and pinoxaden. Group B includes iodosulfuron-methyl and pyroxsulam. Group G is glyphosate.

“The results of this survey, particularly on glyphosate resistance, are causing us some concern,” said Rolston. 

“We are now working to understand how to manage such resistance on cropping farms.”

The survey will probably move into South Canterbury next summer and Ashburton district the year after. It should eventually cover all major cropping districts including in the North Island.

The facts

What to do if you are concerned about resistance on your farm:

❱❱ Check paddocks after herbicide application and remove any plants which have ‘escaped’ treatment

❱❱ Do not allow any ‘escaped’ plants to go to seed

❱❱ Contact your agrichemical rep or FAR if you believe that ‘escapes’ are the result of resistance, rather than application conditions

❱❱ Consider the use of non-chemical weed control.

More like this

FAR researcher of the year

The Foundation for Arable Research (FAR) says it has named one of its own as their 2019 Researcher of the Year.


Report highlights good pay packets

A report confirming a sharp rise in pay for dairy sector workers will help attract more New Zealanders to farming jobs, says Federated Farmers dairy chair Chris Lewis.

Saving livestock and lives

With $1 million now behind them, Hawkes Bay Rural Advisory Group is working to get as many farmers and livestock through winter as possible.


» The RNG Weather Report

» Latest Print Issues Online

The Hound

Dirty water

The Hound understands that Federated Farmers has been cut out of the information loop, for the past year, on the…

Who’s paying?

Your canine crusader noticed a full-page ad recently run in a farming paper calling on meat companies SFF and Alliance…

» Connect with Rural News

» eNewsletter

Subscribe to our weekly newsletter

Popular Reads

Drop in payout looms

Dairy farmers are being told to brace for a big drop in milk payout next season.