Necrosis in field beans (Vicia faba) induced by interactions between bean leaf roll, pea early‐browning and pea enation mosaic viruses

Abstract

SUMMARYMixed infections with two or three viruses ‐ bean leaf roll (BLRV), pea early‐browning (PEBV) and pea enation mosaic (PEMV) ‐ were detected in plants showing leaf curling, stunting and necrosis in a crop of field beans grown for seed in 1980. In glasshouse tests, field bean plants infected with any one of these viruses showed no necrosis, and plants infected with PEBV and PEMV together showed symptoms of PEMV only. However, mixed infection with BLRV and PEMV almost invariably induced severe stunting and leaf necrosis, and infection with BLRV and PEBV often induced both leaf and stem necrosis and sometimes caused early death. Thus it seems that the necrotic symptoms seen in the field were induced by interactions between BLRV and the other viruses.No transmission of PEBV was detected through seed harvested from the crop, but up to 5% transmission was detected through seed from experimentally‐infected plants. The infected seedlings were symptomless.