Diseases of Field Beans

Anthracnose | Bacterial blight and Halo blight | Root rot. | Stem rot (White mold).| Mosaic virus

Anthracnose.
Colletotrichum lindemuthianum

What to look for?
Total crop loss can occur with susceptible cultivars. There are very many races of the fungus and very many genes in the host plant for resistance. Brown to red lesions can occur on all parts of the plant - see bean under vegetable crops.

Photo: Seaman

Picture description
Anthracnose lesion on bean stem.

Photo: Seaman

Picture description
Anthracnose damaged seed.

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Management strategy
The fungus survives on crop residue and on infected seed. Effective control is using resistant cultivars along with disease-free seed and a systemic fungicide seed treatment to reduce, prevent or minimize the introduction of new races of this pathogen.

Bacterial Blight and Halo Blight
Xanthomonas campestris pv. phaseoli , X. phaseoli var. fuscans, Pseudomonas syringae pv. phaseolicola

What to look for?
Common, fuscous and halo blights are frequent and destructive diseases of dry beans. All three diseases are difficult to distinguish from one and other in the fields.

Photo: Zimmer

Picture description
Severe blight on beans.

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Management strategy
Some cultivars are resistant to halo blight but none to the Xanthomonas blights. Control is via clean seed, avoidance of working fields when the foliage is wet and copper based fungicides.

Root Rot.
Fusarium solani f.sp. phaseoli

What to look for?
Lesions caused by Fusarium are elongate and red brown. This is a soil-borne fungus favored by cold wet soil conditions.

Photo: Platford

Picture description
Fusarium infection on lower stem.

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Management strategy
Resistant cultivars grown on well drained soil with good tilth will reduce disease levels along with 3 - 4 year crop rotations.

Stem Rot (White Mold).
Sclerotinia sclerotiorum

What to look for?
Sclerotinia causes major crop losses wherever beans are grown. All above ground parts can be attacked especially old flowers. Most, if not all, infection arises from ascospores. Mycelium on old flower parts move in to infect pods and leaves and extends to adjoining plants.

Photo: Zimmer	Picture description	Photo: Platford	Picture description
. Photo: Evans	. Picture description Sclerotinia harvested along with the beans.	. Photo: Evans	. Picture description Pod infection that move quickly to other parts of the plant in contact with the pods.

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Management strategy
The only effective control is fungicide application during flowering to protect the flowers. Crops with dense canopies and a field history of this disease benefit most. Some resistance in beans is related to their upright growth habit.

Mosaic Virus.
Bean Yellow Mosaic Virus

What to look for?
Bean yellow mosaic is aphid transmitted but is not seed transmitted as is the case with common mosaic - see bean under vegetable crops for further information. Bean yellow mosaic is rare in Alberta bean crops.

Photo: Platford

Picture description
Yellow mosaic infection.

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Management strategy

Photographs and information assembled and prepared for ARD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd.

Diseases of Field Beans

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