Bacterial wilt is caused by the bacterium Curtobacterium flaccumfaciens subsp. flaccumfaciens. This pathogen grows throughout the water conducting tissues of the plant and impedes water movement, resulting in a wilt. Symptom development is favored by temperatures greater than 90°F. Infection is often caused by the planting of infected seed, but the pathogen may also survive in infested crop debris. Wilt bacteria are more confined to internal infection of plant vascular tissue, and apparently are not spread as readily by rain or movement of machinery through wet plants as compared to the halo or common bacterial blight pathogens of bean. Infection through natural openings on the plant are rare, but hailstorms and wounding favor infection. The bacterial wilt pathogen is disseminated among fields by irrigation water and movement of infested crop debris or contaminated seed.
Bacterial wilt infection of young seedlings causes stunting, wilting, and eventual death of the plant. Larger plants that become infected may survive the entire season and produce seed. Leaves of older infected plants will wilt, especially during moisture stress and the warmer parts of the day. Golden brown, irregularly shaped leaf lesions occur, and affected leaves may drop off. Infection can occur on pod sutures similar to that caused by common and halo blights, but it seldom causes circular water-soaked spots. The bacteria may cause a bright yellow, orange, or purple color under the seed coat, depending on the strain of wilt organism present and the market class of bean that is infected. The disease occurs infrequently in the High Plains, but can be damaging when it occurs.
No biological control strategies have been commercialized for bacterial wilt.
Plant only high quality, certified seed free from the bacterial wilt pathogen. Varieties differ in their susceptibility to bacterial wilt, and resistant or tolerant varieties should be planted if available. Practice a two year rotation to non-hosts such as small grains. Avoid reuse of irrigation water, if possible. Practice strict sanitation of crop debris and volunteer beans to reduce pathogen survival between bean crops.
Antibiotic seed treatment can reduce surface contamination of seed, but chemical controls are most effective when integrated with sound cultural practices.
Product List for Bacterial Wilt:
Pesticide |
Rate per Acre |
Application Frequency |
Remarks |
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Streptomycin: not all formulations listed |
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Agri-Strep 500 |
13 oz (6.6) |
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Slurry seed treatment (50,000 ppm) |
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The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Dry Bean, Disease, Bacterial Wilt
Date: 04/01/2007