Combining Single-Gene-Resistant and Pyramided Cultivars of Perennial Crops in Agricultural Landscapes Compromises Pyramiding Benefits in Most Production Situations

Summary

This modelling study uses the spatially explicit stochastic model landsepi to evaluate resistance deployment strategies in perennial crops, with focus on grapevine downy mildew. The research demonstrates that pyramiding benefits are substantially compromised when single-gene-resistant cultivars are grown concurrently in the wider landscape (hybrid strategies), particularly when pathogen mutation probability is low. The effectiveness of different strategies is highly dependent on whether pathogen fitness costs apply broadly across all hosts or only for unnecessary virulence, and on the magnitude of that cost, though field size itself does not substantially influence outcomes across a wide range of conditions.

UK applicability

The findings are relevant to UK viticulture and horticultural disease management policy, particularly regarding cultivar deployment recommendations and landscape-scale planning for disease control. However, applicability depends on whether UK grapevine production systems and pathogen genetics match the modelled conditions (primarily downy mildew in perennial crops).

Key measures

Evolutionary control (pathogen adaptation rates), epidemiological control (disease suppression), fitness costs of virulence, mutation probability, field size effects, deployment strategy efficacy

Outcomes reported

The study compared evolutionary and epidemiological control effectiveness across spatial scales and resistance deployment strategies (pyramiding, mixture, mosaic, and hybrid strategies) using spatially explicit stochastic modelling. Results quantified how concurrent planting of single-gene-resistant and pyramided cultivars affects the durability of resistance to downy mildew in grapevine.

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