This has forced growers to re-assess their fungicide programmes and include new mode of action fungicides to tackle what is an emerging issue in New Zealand.
 

This approach is already making a difference.
 

Andy Bailey, global expert and cereal fungicides technical specialist at crop protection company Adama UK, has been urging barley growers to consider multisite protectant fungicide Phoenix for several seasons now. He says this is an imperative given the rapid evolution of Ramularia resistance and non-renewal of chlorothalonil in the UK.
 

The key to delivering high yields and good grain quality in barley is to maximise the crop’s green area index – protecting and

retaining tillers for as long as possible – and to maximise grain storage capacity and grain filling by promoting healthy spikelet and ear development.
 

Following on from the success in the UK, which felt the impact of resistance earlier, recent label approvals in New Zealand of

Adama’s Phoenix Fungicide (Phoenix) and Bolide to control Ramularia have provided a boost to embattled farmers in this country.
 

There is no doubting that barley growers were struggling with the disease last season.

High rainfall, up until mid-December, also made conditions ideal for it to flourish.

Andy Bailey recommends spring spray programmes be designed to reduce the effect of infection on tiller numbers early in the season and to keep the entire plant as green as possible for as long as possible.
 

“A well-timed T1 spray, which protects the crop around tillering, is therefore critical and should be followed by an equally effective and long-lasting treatment at T2 to provide continued protection.”
 

He admits that despite their earlier experience with Septoria resistance in wheat, the speed of development of Ramularia resistance in the Northern Hemisphere took everyone by surprise.
 

While resistant strains had been seen in Germany, the rapidity of the spread was unexpected.
 

“We were in a situation where we were struggling to control Ramularia in barley in the UK and Ireland.
 

“Historically, this has been a pathogen which has been confined to Ireland and the north of England and Scotland, but in season 2016/17 it was seen throughout England. Now we have Ramularia resistance to almost all key chemical groups.”
 

Multi-site chemistry Phoenix (phthalimide – Group M4) has come to the rescue, Adama says.
 

Its active ingredient folpet works against the disease at a cellular level using a multisite action; inhibiting spore germination and cell division, and reducing energy production in the mitochondria.
 

Phoenix also does not inhibit DMI uptake, ensuring full availability and speed of activity of the applied dose.
 

There is currently no known resistance to folpet.
 

Phoenix’s efficacy has also been confirmed in NZ by FAR trials (FAR Crop Action Edition 134, 14. September 2018).
 

As part of its Ramularia resistance programme, Adama NZ recommends using Phoenix with Bolide or other triazole chemistry.
 

Bolide is an all-rounder DMI fungicide, which provides broader spectrum control of key cereal diseases. It contains an innovative combination of two powerful Group 3 DMI fungicides – epoxiconazole and prochloraz.
 

For more detail visit www.adama.com.