Bean Diseases
Bean diseases can be seen in different forms. These diseases can be caused by various microorganisms, fungi, bacteria, or viruses. Here are some common diseases that can affect bean plants:
Alternaria Leaf Spot (Alternaria alternata) Disease in Beans
Alternaria Leaf Spot Disease in Beans is a common fungal disease in bean plants. This disease is caused by the Alternaria alternata fungus. Alternaria Leaf Spot usually forms brown, irregular spots on the plant's leaves.
- Symptoms: Initially, symptoms are seen as small yellow/white spots on the leaves. Later, the spots enlarge and raised tile-red rust pustules (uredinia) are seen. Normally, these pustules are surrounded by a yellow halo. If the disease is severe, early leaf drop may occur.
- Causative Agent: Fungus
- Disease development conditions: Spores (urediniospores) spread from one area to another by air. Black teliospores formed at the end of the crop season overwinter in the field and serve as inoculum for the next season's crops.
- Control method: Available resistant varieties should be preferred. Infected crop residues should be removed. The field should be cleared of weeds. If the disease is severe, appropriate fungicide is sprayed.
Anthracnose (Colletotrichum lindemuthianum) Disease in Beans
Anthracnose disease in beans is a fungal disease affecting bean plants. The cause of this disease is usually the Colletotrichum lindemuthianum fungus. Anthracnose is commonly seen especially in humid and warm weather conditions.
- Symptoms: Small, dark brown to black lesions on cotyledons; oval or eye-shaped lesions on stems, which turn sunken and brown, with margins ranging from purple to red; if cankers weaken the stem, stems may break; pods dry and shrink above areas with visible symptoms; reddish-brown spots on pods that become circular and sunken with rust-colored margins.
- Causative Agent: Fungus
- Disease development conditions: Disease transmitted through infected seeds; The fungus can survive in crop residues in the soil and re-infect the crop the following season.
- Control method: Plant resistant varieties; certified disease-free seeds should be used; avoid sprinkler irrigation and water facilities at the base; bean crop residues can be plowed into the soil.
Bean Rust (Uromyces appendiculatus) Disease
Bean rust is a fungal disease affecting bean plants and is usually caused by the Uromyces appendiculatus fungus. This disease is commonly seen especially in humid and cool weather conditions.
- Symptoms: Initially, symptoms are seen as small yellow/white spots on the leaves. Later, the spots enlarge and raised tile-red rust pustules (uredinia) are seen. Normally, these pustules are surrounded by a yellow halo. If the disease is severe, early leaf drop may occur.
- Causative Agent: Fungus
- Disease development conditions: Spores (urediniospores) spread from one area to another by air. Black teliospores formed at the end of the crop season overwinter in the field and serve as inoculum for the next season's crops.
- Control method: Available resistant varieties should be preferred. Infected crop residues should be removed. The field should be cleared of weeds. If the disease is severe, appropriate fungicide is sprayed.
Black Root Rot (Thielaviopsis basicola) Disease in Beans
Black root rot Thielaviopsis basicola disease in beans is a plant disease caused by the Thielaviopsis basicola fungus. This disease specifically affects the root system in bean plants and usually spreads in warm and humid conditions. Black root rot can be seen in all growth stages from young seedlings to mature plants.
- Symptoms: Elongated red-purple lesions in root tissue turning dark gray to black; lesions merge to form large dark areas on roots and stems; deep lesions can cause growth stunting, leaf wilting, leaf drop, and plant death.
- Causative Agent: Fungus
- Disease development conditions: Fungi survive in plant debris in the soil.
- Control method: Crops can be used in rotation with non-susceptible grasses; excessive irrigation or drought stress should be avoided.
Fusarium Root Rot Disease in Beans
Fusarium root rot disease in beans is a plant disease caused by the fungus called Fusarium solani. This disease is usually transmitted by Fusarium solani spores found in the soil. It can cause root rot and general growth weakness on bean plants.
- Symptoms: Young plants stunted with chlorotic leaves; older plants with chlorotic leaves and some leaf drop; hollow and dry, severely rotted roots.
- Causative Agent: Fungus
- Disease development conditions: The fungus can stay alive in the soil for several years.
- Control method: Long-term crop rotation is applied; avoid over or under watering the plants; some bean varieties show some tolerance.
Halo Blight (Pseudomonas savastanoi pv. phaseolicola) Disease in Beans
Halo Blight in Beans is a plant disease caused by the bacterium Pseudomonas savastanoi pv. phaseolicola. This bacterium usually manifests itself by forming spots on the leaves and branches of bean plants. Halo Blight is commonly seen especially in humid and rainy weather conditions.
- Symptoms: Small, water-soaked spots on the underside of leaves that become necrotic and visible on the upper surface; lesions may develop an area of chlorotic tissue around the spots; lesions on expanding leaves may cause deformation of the leaves; red-brown lesions may be seen on pods; pod lesions may ooze or turn bronze in color.
- Causative Agent: Bacteria
- Disease Development Conditions: The bacterium survives in seeds and crop residues and enters plants through natural openings such as stomata and spreads through splashing water and soil movement.
- Control Method: Disease-free seeds are planted to reduce bacterial levels or seeds can be treated with an antibiotic; after harvest, bean residues can be plowed deep into the soil.
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