Category Archives: Bean Diseases
Powdery mildew
(Erysiphe polygoni) Credits:Biovision-Infonet A white powdery mould appears on the upper leaf surfaces. Severely diseased leaves turn yellow and die. Leaf petioles, stems and pods can also be affected. What to do: Plough under bean debris after harvest. Practise a 2-3 year crop rotation without legumes. Avoid continuous bean cropping.
Anthracnose
(Colletotrichum lindemuthianum) Credits:Biovision-Infonet Symptoms of anthracnose can appear on any plant part. Pale brown sunken spots may appear on the cotyledons of infected seedlings. Water may spread the disease to the hypocotyl, which if girdled, kills the seedling. Lesions on leaves are dark brown. They are restricted to the veins on lower leaf surface. On stems, lesions are […]
Bean Common Mosaic Virus
Symptoms of bean common mosaic virus (BCMV) are cupping and twisting of leaves with a light and dark green mosaic pattern. The dark green tissue is often bubbled and/or in bands next to the veins. Affected plants produce smaller, curled pods with a greasy appearance, and yields are reduced. The virus is seed borne. It […]
Root-knot Nematode
Credits: Biovision-Infonet They cause stunting and yellowing of plants with a tendency to wilt in hot weather. If infested plants are pulled out from the soil, the roots can be seen to be distorted, swollen and bearing knots of various sizes. Infested roots under severe infestation decay. These knots should not be confused with legume […]
Angular Leaf Spot
Credits: Biovision-Infonet Symptoms consist of small dark brown spots with angular edges and are often numerous to give the foliage a checker-board appearance. The spots may increase in size, join together, and cause yellowing and necrosis of the affected leaves. This may lead to premature defoliation. When humid, the fungus produces a grey mould on the lower […]
Halo Blight
Credits: Biovision-Infonet The most characteristic halo blight symptoms occur on bean foliage. Initially, small water-soaked spots resembling pin pricks appear on the lower leaf surface. These spots turn brown in a few days, and the surrounding tissue gradually become yellow-green. This zone of yellowed tissue around the spot resembles a halo, hence the name of […]
Bean Rust
Credits: Biovision-Infonet Rust spots (pustules) appear on all parts above the ground. They are most numerous on leaves, particularly on the underside. They are less abundant on stems and occur sparingly on pods. Initial symptoms are minute, slightly raised yellow pustules, which later become distinct circles, reddish brown in colour and surrounded by a yellow […]
Fusarium Root Rot
Credits:Biovision-Infonet Seedlings infected with Fusarium root rot appear dwarfed. The primary leaves are often yellow, later turning necrotic and finally the seedlings wilt. Fusarium species infect bean roots when the soil is too wet, or too hot for good bean growth. The fungus survives in soil for long period.What to do: Plough deeply bean debris after harvest. Practise a 6 to […]
Common Blight
(Xanthomonas axonopodis pv. phaseoli) Credits: Biovision-Infonet This disease is a constraint to bean production in Kenya. Crop losses of between 10 and 75% have been reported. The common blight produces similar symptoms on leaves, pods, stems and seeds. Small water-soaked spots are the first symptoms observed on leaves and appear within 4 to 10 days of infection. […]