Causal Agent:
Bacterium (Xanthomonas campestris pv. campestris)
| Characteristic Symptoms: | |
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Infected plants first exhibit 1-3 cm of irregular, dull yellow lesions along the leaf margins that expands towards the midrib creating a V-shaped lesion with broad yellow margin and dry brown center. |
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Leaves defoliate and vascular tissues become dark |
| Conditions for Disease Development: | |
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The pathogen infects a wide range of brassica crops and weeds |
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Warm, humid conditions and temperatures not exceeding 25°C are favorable for the bacterial growth
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Early infection of seedlings can result in severe stunting and plant death |
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Infected transplants, seedbeds, heavy rain or overhead sprinkler/ irrigation water can rapidly spread the bacteria many meters from the infected plant |
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The pathogen is seedborne and can survive on plant debris and in the soil |
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Infection is more likely to occur before transplanting, during late flowering and seed maturation |
| Management and Control: | |
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Use of pathogen-free seeds
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Hot water treatment of suspected seed lots at 50 °C (25 min for cabbage, broccoli and Brussels; 15 min for cauliflower, kohlrabi, kale, turnip and rutabaga) |
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Strict field sanitation and monitoring for early symptoms
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Remove infected plants from seedbeds and close monitoring of the remaining plants |
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Avoid overhead watering and furrow irrigation |
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Disinfection of tools and equipment after use |
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Remove volunteer and weedy crucifers that may serve as alternate hosts for the pathogen. |
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Spray with protective copper-based fungicides (e.g. Cupravit®, Vitigran Blue®, Nordox 50®). |
References
Agriculture and Natural Resources Publication, FSA7549. Diseases of Turnip and Mustard Greens
https://www.uaex.edu/publications/PDF/FSA-7549.pdf
Compendium of Brassica Diseases by APS (2007)
To view other diseases, click here.
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