Dry Edible Beans: Bean Common Mosaic Virus

Excerpt from Agronomy Guide for Field Crops (Chapter 7)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Incidence
2. Appearance
3. Disease Cycle
4. Management Strategies
5. Updates on Dry Edible Beans: Bean Common Mosaic Virus
6. Related Links

Incidence

Bean common mosaic virus has been found wherever edible beans are grown in the province. In some years, the disease can be severe in individual fields.

Appearance

Infection of edible beans with the virus can cause various symptoms. Leaves of infected plants have a mosaic of light yellow-green and dark green patches that are puckered. The leaves curl downward along the margin. Plants are stunted and if infection occurs early, they may flower but not produce seed. Another symptom referred to as "black root reaction" is displayed in varieties containing a specific gene (dominant resistant gene I). These varieties are resistant to all strains of bean common mosaic virus except when plants that are growing at high temperatures react to the virus (hypersensitive response), causing the "black root reaction." The result is a browning or blackening of the vascular tissue inside the stem, wilting and plant death. The obvious symptom of "black root reaction" is the discolouration or streaking of the outer stem (water-conducting tissue), which produces a black or brown outer streaking of the stem from the soil line up. This blackening may only be visible on one side of the stem.

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Disease Cycle

The virus is primarily spread from field to field through infected seed. Aphids can then spread the virus within the field. Severe losses occur when susceptible varieties are infected early either through infected seed or from being close to other infected plants or fields that have high aphid populations. There are several strains of the virus, but the predominant one in Ontario is strain 1.

Management Strategies

Do not plant seeds harvested from diseased plants. For a list of disease-resistant varieties, consult the OMAFRA Factsheet, Performance Trials for Dry Edible Beans, or visit the Web site at www.omafra.gov.on.ca/english/crops/index.html each year. Avoid damaging the plants during cultivation.

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Updates on Dry Edible Beans: Bean Common Mosaic Virus

No updates available at this time.

Related Links

• Disease
• Dry Edible Beans
• Field Crop Protection Guide - Publication 812

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