Common Bacterial Blight (Xanthomonas axonopodis pv. phaseoli) of Beans with Special Focus on Ethiopian Condition

Abstract

Common bacterial blight (CBB) is the most devastating factor that affects common bean crops in all common bean growing areas. This review was to review with an objective of reviewing the biology, economic importance of CBB of common bean crop disease and its management options, with an emphasis on the future research direction and priorities. CBB disease, caused by the gram-negative bacterial pathogen Xanthomonas axonopodis pv. phaseoli (Xap) and its fuscans variant Xanthomonas fuscans subsp. fuscans (Xff) is the major bottleneck in bean production in the world as well as in Ethiopia. It is a serious bacterial disease of common bean which causes lesions on the leaves, stems, pods and seeds of the plant. The disease affects seed quality and can reduce yield by up to 45%, may be more in susceptible cultivars. CBB is very difficult to control due to seed-borne nature of the bacteria and its capacity to produce huge amounts of secondary inoculum. Since the disease is very important in causing economic losses of yields on bean crop, developing and using effective and appropriate management options is unquestionable. Using resistant varieties supplemented with chemical seed treatment and proper cultural practices could be the best alternative options in managing common bacterial blight of common bean and avoiding yield loss. In general, integrated disease management is the preferred strategy because of increased understanding on residual effects of chemical control on non-target organisms and environment as well as the limitation of a single alternative management option to achieve the same level of control and reliability as that of chemical. In the case of Ethiopia, emphasis should be given to developing multi line resistance varieties by suitable breeding practice and developing molecular markers to enhance marker assisted selection.

Common bean resistance to Xanthomonas is associated with upregulation of the salicylic acid pathway and downregulation of photosynthesis

“…Common bacterial blight of bean (CBB) is one of the main threats to bean cultivation with yield losses of more than 40% under favourable conditions [20,21] and up to 75% in the most severe cases [22,23]. CBB is characterized by water-soaking spots on leaves, stems and pods, further evolving into necrotic lesions sometimes surrounded by a chlorotic halo in leaves.…”

Evaluation of Common Bean (Phaseolus Vulgaris L.) Genotypes for Disease Tolerance Under Rain-Fed Conditions

“…Angular leaf spot is not an important disease in most bean producing areas, however, under favorable environmental conditions, disease epidemics can occur. Optimal temperatures for germination of conidia of P. griseola range between 23 to 27°C, and infection occurs from 16 to 28°C with the optimum for infection and disease development at 24°C (Belete and Bastas, 2017) Transmission of pathogens which causes bacterial diseases in common beans is accelerated by low pod clearance. In this study, although there was a significant difference between commercial varieties and breeding lines in relation to pod height, DAB 539, Gloria and DAB 194 had the highest clearance from the ground.…”

Developing Common Bacteria Blight Disease Detection Model for Common Bean Using Deep Learning Approach

“…The gram-negative bacterial pathogen Xanthomonas axonopodis pv. phaseoli (Xap) and its fuscans variant Xanthomonas fuscans (Xff), which causes CBB [2]; is the main obstacle to common bean production globally. CBB is proven to be a major problem in the majority of common bean production areas around the world including Ethiopia.…”

“…Treating the common bean crop disease in its early stages can increase [7], [8] the quality and quantity of the products. Recently many researchers from the agriculture field of study in Ethiopia tried to overcome the impact of this disease on the common bean in many ways like using [2], [8] the most preferred seeds, detecting disease by observation, and also using drugs to prevent disease. This is a very tedious, time-consuming, and costly technique that needs many experts as well as more effort [7].…”