Identification

Caused by bacteria and may occur during tillering stage. Overwintering occurs in infected seeds, straws, stubbles, crab grass etc. Spread of the disease is facilitated by rain, wind, dew, irrigation etc.. Typhoon, storm or floods can help spread of the disease. Symptoms:

  • Leaf blight – occur at late tillering stage. Starts from apex or edges, scabs are ‘turn V’ shaped and spread along edges (Fig 1). There is yellow bacterial oozing out, turning into bacterial glue.
  • Acute type – these are dark green scabs on leaves, within a few days, the whole leaf becomes grey-green (Fig 2). Leaves are rolled and withered, and with bacterial ooze drops.

Control options

Cultural control: Choose resistant varieties. Remove infected straws, stubbles, wild rice plants and weeds in time. Choose clear and higher located fields for nursery and keep shallow water level in it. Alternate dry and wet fields. Avoid over use of nitrogen fertilization and thus very fast growing plants, and also avoid acidic soil and high water levels because the latter favours the disease.

Chemical control: a fungicide according to recommendations provided in the Green & Yellow List may be sprayed when infected areas are identified in the fields.