First Record of Faba bean necrotic yellows virus and Beet western yellows virus Infecting Faba Bean in Tunisia.

Abstract

A survey was conducted in April 2000 to identify viruses infecting faba bean (Vicia faba L.) in seven regions (Beja, Bizerte, Cap-bon, Jendouba, Kairouan, Siliana, and Zaghouan) of Tunisia. Around 4,000 random samples were collected from 34 fields (100 to 200 samples per field). Samples were tested by tissue-blot immunoassay procedure (2) at the Virology Laboratory of INRAT for the presence of 14 different viruses. All antisera used were specific, including those for Faba bean necrotic yellows virus (FBNYV) (1) and Beet western yellows virus (BWYV) (ATCC-PVAS-647). Broad bean mottle, a beetle-transmitted and seedborne virus, was the most abundant with an average incidence of 2.3%. The highest disease incidence occurred with BWYV, which was in 20 and FBNYV in 4 of 98 random samples from a field in the Siliana region; and with BWYV in 7 and BBMV in 21 of 120 samples from a field in the Jendouba region. Other viruses such as broad bean stain, cucumber mosaic, and bean leaf roll were detected rarely (<1%). This is the first record of FBNYV and BWYV infecting faba bean in Tunisia. BWYV was detected in 1.2% of the samples tested collected from 20 fields comprising all seven regions. FBNYV was detected in 0.9% of the samples tested collected from 13 fields comprising all except the Capbon region.