Our understanding of the nature, origin, and biological roles of double-stranded RNA found in fungi, plants, and animals has advanced greatly during the last five years. Because these genetic elements are capable of replication, they can be used to manage fungal diseases of crops, vegetables, turfgrass, fruit, and forest trees using genetic means rather than by environmentally hazardous chemicals. And recent evidence suggests that the presence of small amounts of dsRNA elicits sequence-specific gene silencing, which may lead to the development of treatments aimed at silencing harmful genes...