Abstract
Yield and quality losses due to disease are major factors limiting crop productivity; thus breeding for disease resistance is a primary goal for many plant breeding programmes. Unfortunately, specific sources of resistance are not always available. In cases where sources of genetic resistance are limited or non-existent, manipulating plant architecture to facilitate disease avoidance may be a valuable alternate approach to mitigate disease severity. Modifications of plant architecture can be used to reduce contact with the pathogen, create barriers to pathogen growth and development, or create an unfavourable microclimate for disease development. Architectural variants have long been observed by plant breeders and geneticists, and are frequently utilized to develop new plant types. Key variants that may facilitate disease control include altered plant height, determinacy, branching patterns, branch or leaf angle, flower position, organ coverage or shape, or root structure patterns. Implementing disease avoidance by an architectural approach requires an understanding of both the life cycle of the pathogen and the genetic basis for the desired morphological traits. This review examines examples where modified architecture can be employed to reduce disease. Among the better-documented cases are modified canopy structure to reduce white mould in dry bean and tightly closed ears to reduce Fusarium ear rot of maize. These examples demonstrate that breeding for modified plant architecture can be a valuable component of a broader disease control strategy that also includes genetic resistance and cultural and chemical controls.