Halo blight of bean is a bacterial disease caused by Pseudomonas syringae pv. phaseolicola. Halo blight is affected by environmental factors and enters through plant injuries or natural openings. The development of the Halo blight is highly favored by cool temperatures (such as 20–23 °C), unlike other common bacterial blights. Halo blight causes small water-soaked spots on leaves. These spot progressively turn dark brown and are surrounded by a wide greenish-yellow halo. The necrotic spots remain small unlike that of common blight. Similar to foliage symptoms, halo blights cause water-soaked spots on vegetative pods. It also causes streaks along pod sutures. If lesions become severe on the pods, it may penetrate the pod walls or expand into the pod sutures which causes the seed to be wrinkled and discolored (yellow patches on the seed coat). Systemic infections are not common, but occur more favorably in some dry bean varieties. If the disease develops a systemic infection, it will cause curling, yellowing and death of young leaflets.