Chlorothalonil (Bravo) was the backbone of disease control programmes in wheat and barley for many years, until its regulatory demise in 2020. Most growers applied the principle that Bravo was ‘the first thing into the tank’ where Septoria was the target disease on wheat or Ramularia was in the mix on barley.
The loss of chlorothalonil left a void in disease control programmes, but the rationale for using chlorothalonil can now be applied to alternative multi-site chemistry, principally Folpet.
Syngenta’s Billy Cotter explains multi-site chemistry - Folpet - and how it performs two tasks in disease control programmes.
Folpet – the essential multi-site fungicide
“Firstly Folpet’s inherent fungicidal properties deliver disease control benefits on top of whatever partner fungicides it is applied with, explained Billy.
“We have seen this clearly for Septoria on wheat and Ramularia on barley, and it can also be observed with other diseases like rusts and net blotch. The disease control and the associated yield benefits are sufficient justification for adding Folpet to programmes.”
Beyond this, Mirror, which is Syngenta’s main Folpet brand, performs a higher function.
“As a multi-site interfering with several biochemical pathways in the fungus, Mirror is not prone to the resistance or reduced sensitivity threats that apply to most of the other single site fungicide chemistry being used. This is critical to protect these other fungicides from sudden swings in performance,” said Billy.
Essentially Folpet acts as a sweeper, picking up and controlling mutations or strains of disease that might have escaped the partner single site fungicide.
“It’s not perfect but will at least slow the pace of resistance development to the partner chemistry. It is very important to protect the current fungicide toolbox because replacement modes of action are not easy to find,” Billy added.
Syngenta have been working with Folpet in Ireland since 2019, when it became apparent that chlorothalonil did not have a long term future.
“Our trials programme over three years indicates yield benefits in the order of 0.4 to 0.5 tonnes per hectare on wheat. This is from two applications of Mirror at 1.5 litres per hectare at T1 and T2,” he said.
“On barley, the yield response is a little more variable. We see on average a 0.3 to 0.4 tonnes per hectare benefit however, we have seen yield responses multiples of this, where we have had high pressure on Ramularia susceptible varieties,” explained Billy.
The final application on barley, when the awns are emerging, is the critical timing, stressed Billy.
However, winter barley will also benefit from a flag leaf application of Mirror.
The 1.5 litre per hectare rate is also appropriate on barley.