Abstract

The study was conducted to screen local and improved bean varieties for resistance to halo blight disease caused by Pseudomonas syringae pv. phaseolicola. A total of eight improved (Sokoine University of Agriculture (SUA) 90, Rojo, Zawadi, Mshindi) and local (Mwasipenjele, Masusu, Kabhaya, Mabula) bean varieties were collected from breeders at SUA and farmers at Ileje district in Songwe region. Isolation of P. syringae pv phaseolicola from bean seeds was conducted using Liquid Assay method. Results indicated that, bacterial isolate L1 from local bean variety Mwikala produced similar characteristics as those obtained from reference strain of P. syringae pv phaseolicola in the biochemical and pathogenicity tests on host plants. Using bacterial isolate L1, there was significance difference (P < 0.05) on incidence and severity of halo blight disease. The highest disease incidence had (89%) was on local bean variety Mabula, while the lowest had (67%) was on improved varieties Zawadi and Mshindi. Disease severity of improved varieties zawadi and mshindi when compared with other varieties were at low severity (disease score 4). It was concluded that the Zawadi and Mshindi were less susceptible to halo blight disease. This study needs to be repeated if same results were obtained aside these two improved varieties (Zawadi and Mshindi) of bean which could be recommended to farmers.

Key words: Assay, incidence, inoculum, isolate, Pseudomonas syringae pv. phaseolicola, disease severity.