Managing concurrent evolution of resistance to fungicides (PhD)

The challenge

Concurrent selection for resistance against two or more modes of action

When two or more single-site acting fungicide modes of action (MOA) are used (e.g. SDHIs and azoles), resistance will evolve to them at the same time. The challenge is, therefore, to use mixtures to maximise mutual protection against resistance. Yet, the UK and global experimental evidence is from studies where selection for resistance against only one of the MOA was measured. We, therefore, rely on inference to derive strategies to manage concurrent evolution.

‘Trade-offs’ between mixtures, alternation and number of treatments

Restrictions on the maximum number of treatments per crop with a MOA are widely used. There is a trade-off, however, because that MOA cannot then be used in a mixture to protect other MOA. Hence, limiting the maximum number of treatments constrains the availability of effective mixtures at some spray timings and moves practice towards alternation or the use of less effective mixtures.

The project

This PhD project will develop modelling approaches, in close collaboration with field experimentation, to develop guidance for fungicide resistance management programs where resistance is evolving to multiple MOA. The student will:

1. Develop epidemiological models and apply them to fungicide resistance dynamics
2. Parameterise models and test model performance
3. Extend models to include new aspects of the biology of pathogens (here: sexual reproduction and initial infection from ascospores)
4. Apply models to study the concurrent selection for resistance to two MOAs
5. Extend the methods of model analyses to systematically compare large sets of application programs
6. Apply this method to study the trade-offs between mixtures, alternation and number of treatments
7. Translate research findings into practical messages

The benefits

The project will:

• Identify management strategies which are most effective at slowing the spread of insensitive septoria isolates to current MOA
• Improve guidance to protect new MOA against development of resistance in septoria and other pathosystems

Student: Isabel Corkley.

Supervisors: Dr Alice Milne (Rothamsted Research) and Dr Alexey Mikaberidze (University of Reading).