Understanding Prosaro

Prosaro combines a mixture of prothioconazole and tebuconazole. Prothioconazole is the active ingredient in fungicides such as Proline, Aviator Xpro and Delaro and is often thought of as the most effective DMI fungicide, while tebuconazole is the active ingredient in Bayer's well established wheat fungicide, Folicur.

Mixing DMI fungicides in ready formulated products is an approach that brings many benefits, both in terms of effective disease control and in the management of disease resistance, something which has been common practice in Europe for many years. It is commonly referred to as “DMI Stacking”.

To understand why Prosaro is so effective it is important to explain a little about resistance and DMI fungicides.

DMI (DeMethylation Inhibitors) fungicides such as Prosaro act in a disruptive manner within the fungus causing the enzyme pathway responsible for the production ergosterol to malfunction. Without ergosterol, an essential component of fungal plasm membranes, many types of fungi cannot survive.

As DMI fungicides like Prosaro (along with all other DMI fungicides) act on one biochemical chain they are at risk of resistance developing. However, for resistance to develop to DMI fungicides several mutations have to occur within the fungus, making the development of resistance more difficult.

But however difficult, it isn’t enough to stop some fungal strains outwitting the fungicide. Fungal strains which carry the genetic make up allowing them to shrug off the impact of using a DMI fungicide do occur. This is where DMI Stacking or the mixing of two different DMI fungicides is so powerful.

Extensive work carried out by Dr. Andreas Mehl, one of Bayer's leading experts in fungicide resistance globally, has proved that different populations of Septoria leaf blotch exist and that they tend to form clusters characterised by their susceptibility to DMI fungicides.

What Dr. Mehl discovered is that when strains of Septoria leaf blotch develop showing a level of decreased sensitivity to prothioconazole they can be susceptible to tebuconazole instead. Therefore applying Prosaro ensures they are effectively controlled before they start to become a practical problem in the paddock.

What Dr Mehl found for Septoria leaf blotch can also help with the control of other diseases, devastating diseases such as scald and net blotch. This means that Prosaro can serve as a very effective part of your fungicide programmes, not only in wheat but in barley and ryegrass seed crops as well.

When should I use Prosaro?

Prosaro was introduced in 2014 and it has quickly become established as a “foundation fungicide”, a critical and flexible component of New Zealand fungicide programmes. This has been made possible due to the comprehensive Prosaro label which carries recommendations to control many key diseases in wheat, barley and ryegrass seed crops.


  • Prosaro is the ideal fungicide for wheat, controlling all of the main diseases - Septoria leaf blotch, stripe rust, leaf rust and ear diseases
  • Together with Aviator Xpro, Prosaro, Prosaro allows fungicide programmes to be devised for all wheat crops
  • Prosaro is an easy-to-use, ready mixed fungicide containing two different DMI fungicides. These are combined in the ideal ratio to help slow down the development of Septoria leaf blotch intolerance to DMI fungicides
  • Prosaro is very convenient with just one dose rate for use on all wheat varieties
Prosaro Spray Programmes Arable Fungicides Bayer