The Plant Viruses formatIsbn:Softcover 9781468449396 Notwithstanding past achievements formatIsbn:Hardcover 9781441907714 Notwithstanding past achievements Frameworks Others such as prunus necrotic ringspot or prune dwarf viruses are more restricted in their host ranges but never theless infect important perennial hosts such as stone fruits and reduce productivity considerably Among these are viruses belonging to four groups recognized by the International Committee for Virus Taxonomy: the Bromovirus and Cucumovirus groups whose genomes are encapsi dated in small icosahedral particles or the Ilarvirus and alfalfa mosaic virus groups with spheroidal or bacilliform particles