The use of host resistance in disease management of rust in common bean

Bean rust, caused by Uramyces appendiculatus, is one of the major diseases in dry and snap bean production world-wide. Numerous advancements in disease management have been made to reduce rust losses. Host resistance is an important component of rust management. However, durability of disease resistance has often been short due to the use of single genes for resistance interacting with extremely high virulence diversity of the bean rust fungus. The challenge to increase durability of resistance has led to strategies such as gene pyramiding of race-specific resistance, selection and use of partial resistance, and investigation and discovery of leaf morphological features that may slow the rust epidemic. Germplasm with multiple sources of rust resistance has been developed in specific bean seed classes and released for public and commercial use in intensive production systems such as those in the United States. However, progress to develop rust resistant germplasm for the subsistence agriculture of Latin America and Africa where intercropping and mixed cultivars dominate the production system has been slow. Incorporation of high yielding, disease-resistant components as partial replacement in farmer's mixtures has the potential to reduce severity in the crop and increase yield in the presence of rust. This strategy would not erode the genetic diversity that is historically known to enhance resistance durability and for many years has given stability in production in the subsistent agriculture systems.