Designing mixtures to suppress airborne pathogens (ReMIX Practice abstract)

Summary

Outcome
Pathogens are slowed down and less likely to adapt to all mixture components. Pesticide use is reduced, and varieties will be useful for a longer time.
Practical recommendations
- Variety mixtures: use varieties that can be harvested and used together but differ in their resistance to the pathogen in focus. Because over time the pathogen may adapt and overcome plant resistance mechanisms (Fig. 1 lower right), change the mixture and resistance composition over time.
- Species mixtures: use species that are not susceptible to the same pathogen. Choose species that either can be grown and used together (e.g. for feed) or that are easily separated (e.g. with different seed sizes). Alternatively, use a service species (e.g. undersown) in addition to the species to be harvested. In species mixtures, there is less risk for pathogens adapting. If species mixtures are too difficult, strip intercropping of different species is a good option.
Practical testing/ Farmers’ experiences
Variety mixtures of cereals work very well against rusts, mildew and Septoria tritici, or rice blast in rice. Similarly, species mixtures of cereals with beans or peas usually reduce airborne pathogens in both crops. Undersowing clover in cereals can reduce Septoria.