Bean Halo Blight – Pseudomonas syringae pv. phaseolicola

Bean halo blight Common name Bean halo blight Bacterial blight of bean Grease spot of bean Causal agent It is a bacterial disease of beans caused by bacteria belonging to the genus Pseudomonas. It destroys both the leaves and the pods. Scientific name Pseudomonas syringae pv. phaseolicola Symptoms & Signs Bean halo light symptoms initially include water-soaked spots on the underside of the leaves, which spread to the upper side as the disease progresses. The water-soaked spots are surrounded by a yellow, chlorotic halo giving the disease its name. With time, the chlorosis spreads to the whole leaf with necrosis of the damaged tissues. The pods also exhibit red and brown lesions with bacterial ooze. Transmission It spreads majorly through infected seeds and debris. The bacteria on the seedlings and plant debris are transmitted to other healthy plants by means of animals, water, and wind. High humidity favors the spread of disease. When the temperature drops, it produces a toxin called phaseolotoxin that causes chlorosis in the foliage. Time of concern Throughout fall and spring Common hosts Lima beans Red kidney beans cranberry yellow eye field beans snap beans scarlet runner