ABSTRACT
Efforts to develop new cultivars and varieties of tropical pasture plants have been accompanied by growing lists of associated pests and diseases. This situation is not surprising because most of these emerging cultivars are being developed from recently domesticated plant species, and their pests and diseases are only of recent concern. The greater productivity of tropical pastures “improved” by these new plants compared to that of native grass communities is unfortunately being gained at the expense of greater vulnerability to pests and pathogens due to genetic uniformity. However, this potential for genetic vulnerability is ameliorated somewhat by the diversity of available grass and legume genotypes that can be deployed spatially or temporally to reduce the risk of catastrophic loss due to a single biotic constraint. Some tropical forage genera and species have severe biotic constraints to their utilization, but it is hoped that the growing number of commercial varieties developed from diverse genera and species of tropical forages can replace these.
