SAP‐TRANSMISSIBLE MOSAIC DISEASES OF SOLANACEOUS CROPS IN TRINIDAD

Abstract

Four sap‐transmissible viruses were isolated from cultivated Solanaceae in Trinidad: (1) tobacco mosaic virus, from tobacco, tomato and sweet pepper; (2) cucumber mosaic virus, from tobacco and petunia; (3) ‘pepper vein‐banding virus’, probably related to pepper mosaic viruses in Puerto Rico and Brazil, from peppers and tobacco; (4) ‘egg‐plant mosaic virus’, possibly related to the tobacco ring‐spot virus, from egg‐plant and tomato. Pepper vein‐banding virus causes leaf‐crinkling and vein‐banding in Physalis floridana, petunia, various Nicotiana spp. and most peppers; the Large Bell Hot pepper is killed; tomato and egg‐plant are immune. Egg‐plant mosaic virus produces mosaic, ring‐spotting, or both, on different solanaceous species. It also gives local and systemic ring‐spotting on Chenopodium hybridum and necrotic local lesions on the primary leaves of cowpea (var. Black‐eye); cucumber is a symptomless carrier. Only cucumber mosaic virus was found naturally infecting non‐solanaceous hosts, cucumber and certain common wild plants.The thermal inactivation point of pepper vein‐banding virus is 62° C, its dilution end‐point 2×10‐5 and its longevity in vitro 6 day s at 23–30° C.; corresponding values for egg‐plant mosaic virus are 78° C., 10‐6 and over 3 weeks. Aphisgossypii transmits cucumber mosaic and pepper vein‐banding, but not egg‐plant mosaic, of which Epitrix sp. is an occasional vector. Tobacco mosaic, as elsewhere, probably has no regular insect vectors in Trinidad.