Dry Bean – Diseases

Research underway with Dr. Syama Chatterton, a Plant Pathologist with Agriculture and Agri-Food Canada is looking at spore trapping to help predict disease risk in bean fields.  Please see the one page research summary document “Better Tools in Sight for Dry Bean Disease Management“.  

Disease Prevention

Dry beans are very susceptible to a number of diseases and few chemical control measures are available – it’s important to use an integrated management program in dry bean production. Disease prevention recommendations include:

• Crop Rotation– Follow a diverse rotation with at least four years between dry bean crops which can reduce pathogen loads in the soil. There may be no safe rotation length for some diseases. Avoid planting adjacent to last year’s bean field because many diseases are wind-borne and very mobile (shorter rotations are acceptable as long as diseases are not a problem).
• Field Preparation: Plow residue into the soil to avoid it scattering. Burying it will reduce survival of the pathogens, but take care to avoid erosion issues.
• Seed Source and Handling – Plant clean seed that is disease free, in particular, avoid seed with Bacterial Blight. Planting certified seed produced in arid regions is an effective technique for controlling Bacterial Blight. Seed should be handled gently both in storage and seeding operations to avoid damage to the seed coat. Mechanically damaged seed is prone to fungal diseases during germination, and young seedlings are less vigorous and more susceptible to fungal diseases – Baldhead is also a symptom of mechanically damaged seed.
• Seed Treatments – Seed treatments will help protect seeds and seedlings from seed-borne and soil-borne pathogens and help ensure good establishment of a strong, vigorous crop.
• Variety Selection – Resistance to Common Blight and White Mould is minimal. However, growth habit can affect how wet the canopy stays, greatly influencing the development of diseases like White Mould. Choosing varieties that are more upright may result in a drier canopy with less disease.
• Weed Control – Keep the crop weed free, which will help reduce canopy cover and provide a drier canopy. Some weeds can host pathogens, increasing disease pressure.
• Proper Fertilization – Balanced nutrition is important to avoid nutrient deficiencies that may stress the plant and make it more susceptible to disease. In particular, zinc deficiencies can result in more disease concerns. Over application of nitrogen can also increase disease risk, as a lusher canopy can create a favourable environment for disease.
• Row Spacing and Tillage – Wider row spacing in row crops, compared to solid seeding systems, will have more airflow through the canopy, reducing disease pressure. If soil is compacted and hard, root diseases can be more problematic. Tillage near bean rows to break soil up and allow improved root growth can reduce the severity of root diseases.