ABSTRACT

Polyculture cropping systems are important parts of the agricultural landscape in many areas of the world. Although farmers often use polycultures without applying fertilizers or pesticides, polyculture yield advantages are not restricted to low-input conditions. Much more research is needed before increased yield stability can be assumed to be a general characteristic of polycultures; in cases where stability does increase, more research is needed to understand the causal mechanism. Burdon noted that without appropriate experimental designs, it is impossible to tell whether improved resource use efficiency or decreased incidence of disease symptoms is responsible for higher yields in polycultures. Little research has yet been done on the ecology and management of plant pathogens in polycultures. The task for the future is to better understand the dynamics and complexities of polycultures so that these systems may be refined, transferred, and adapted, and so that benefits can be gained predictably.