Anthracnose – Ever Present Risk In Edible Beans

Edible bean producers have experienced above average yields and excellent quality on all bean types in 2003. However, the year was marked by the appearance of anthracnose in a number of white bean and black bean seed and commercial fields. This is a warning to stakeholders in the industry to follow practices to ensure anthracnose never becomes a problem here, as it has been in other regions of North America.

Anthracnose is not a new disease to Ontario. The introduction of races of the disease not yet present in Ontario caused sudden and severe outbreaks in 1976 and 1993 . A thorough seed inspection program, use of DCT seed treatment, and the development of resistant varieties has practically eliminated the disease. This disease can infect all bean types. If severe, anthracnose causes major yield reductions or loss in quality. Yield and pick losses of over 70% have been documented.

The most striking symptom is rusty brown spots on infected pods that can spread to seed. This causes discolouration and results in reduced grades. Anthracnose overwinters in infected seed and then develops in the next year’s crop. Further development of the disease is favoured by prolonged periods of moderate temperature, high humidity and /or rainfall during the growing season. Rainy weather favours this disease, as spores are splashed from diseased areas and carried in wind-borne water droplets or by surface water throughout the field. The disease can be spread by the movement of people, animals and equipment when plants are wet.

There are over 20 known races of anthracnose. All races of the disease cause the same plant symptoms. Plant breeders have developed varieties resistant to the most prevalent races present in Ontario. Variety reaction to the races of anthracnose are listed annually in the OMAF factsheet, "Performance Trials for Dry Edible Beans".

Growers are encouraged to follow these accepted practices for the control of anthracnose:

• Plant certified seed treated with DCT. Use DCT seed treatment on untreated seed.
• Planting clean seed, no matter what the source, is critical to controlling the disease.
• Avoid entering edible bean fields with equipment or on foot when plants are wet.
• Clean equipment with bleach solution between fields. This is extremely important for seed growers.
• Follow recommended crop rotations with a minimum of two years , but preferably three or more years between edible bean crops.
• Scout fields during the late vegetative to pod fill stage, and if signs of the disease are present, apply a protectant fungicide. "Headline" is a new fungicide registered by BASF, for control/protection of anthracnose on dry beans. Refer to the product label for information on application and use.
• Any suspicious seedlots can be tested for anthracnose for a nominal fee of $35 + GST per sample. A 1 lb. representative sample should be sent to:

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