Bacterial Blights of Beans

Bacterial Blights: Xanthomonas campestris pv phaseoli

  • There are two widespread bacterial blights that affect most types of beans, common blight (Xanthomonas campestris pv phaseoli) and halo blight (Pseudomonas syringae pathovar phaseolicola).
  • The stems, leaves and fruits of bean plants can be infected by either disease. Rain and damp weather favor disease development.
  • Halo blight occurs primarily when temperatures are cool.
  • Light greenish-yellow circles that look like halos form around a brown spot or lesion on the plant. With age, the lesions may join together as the leaf turns yellow and slowly dies. Stem lesions appear as long, reddish spots.
  • Leaves infected with common blight turn brown and drop quickly from the plant.
  • Common blight infected pods do not have the greenish-yellow halo around the infected spot or lesion. Common blight occurs mostly during warm weather.
  • Both of these diseases come from infected seeds. The diseases spread readily when moisture is present.
  • Avoid overhead watering and do not touch plants when the foliage is wet. The bacteria can live in the soil for two years on plant debris.
  • Do not plant beans in the same location more frequently than every third year. Buy new seeds each year.
  • Fixed copper can be applied at ten-day intervals. Wait one day between spraying and harvest.




  • TamilNadu Agritech Portal
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