Figure 39. Deployment strategies for major resistance genes. A) The traditional "plug, plant, and pray" approach of deploying single R genes one at a time in a sequence that matches the boom and bust cycle. B) Rotations of R genes in time or space. Each R gene is deployed over a limited number of years or limited area, and is withdrawn before the corresponding virulence allele achieves a high frequency in the pathogen population. C) R gene pyramid. All R genes are placed together in one plant genotype. D) Regional deployment. Different R genes are grown in different regions. This can be part of a gene rotation as indicated in B. E) Cultivar mixtures and multilines. Individual R genes are grown as an intimate mixture in the same field. 

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