Studies on the occurrence of tomato bushy stunt virus in English rivers

SUMMARY Tomato bushy stunt virus (TBSV) of unknown source was isolated from water of the River Thames, near Oxford. The isolate designated TBSV‐T was mechanically transmissible to several tomato (Lycopersicon esculentum) cvs and to other species including Petunia hybrida , pepper (Capsicum annuum). eggplant (Solanum melongena), Nicotiana clevelandii, Chenopodium amaranticolor and C. quinoa in which it caused systemic symptoms. It caused no infection of globe artichoke (Cynara scolymus) or Pelargonium domesticum. The virus was not adsorbed to soil and could be isolated from leachate of soil in which systemically‐infected tomato or C. quinoa plants were grown. Tomato plants became infected when grown in soil watered with virus suspensions. TBSV‐T was infective after 10 min at 80°C but not at 90°C and when diluted to 10 ‐5 but not to 10 ‐6 . Purified virus preparations contained C. 30 nm isometric particles. In gel‐diffusion serological tests, TBSV‐T reacted with homologous anti‐serum and with antiserum to petunia asteroid mosaic virus but not to pelargonium leaf curl virus. Seed‐borne infection (50–65%) of TBSV was demonstrated in plants grown from seed of symptomlessly‐infected tomato fruit. TBSV was isolated from symptomlessly‐infected tomato fruit imported from Morocco during October‐April 1981. One of the isolates (TBSV‐M) was indistinguishable from TBSV‐T in host range, symptomatology and serological reactions. TBSV was also found in tomato plants growing extraneously in primary settlement beds at sewage works; such plants having been derived from undigested seeds in sewage. Because of its ‘alimentary‐resistance’ in man, it is possible that one ecological route whereby TBSV enters rivers is by man's consumption of TBSV‐infected tomatoes and eventual sewage dispersal into rivers.