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Bacterial panicle blight in paddy

Bacterial panicle blight (BPB) is a high-temperature, high-humidity disease of rice caused primarily by Burkholderia glumae, with B. gladioli as a secondary contributor. It attacks at heading and grain fill, causing panicle blanking, grain discoloration and milling-quality loss.

Identification and symptoms

Affected panicles show discoloured spikelets with a brown band at the base, blanked grains and uneven panicle exsertion. Sheaths can also show light brown lesions. The pattern is patchy in the field and most severe where canopy humidity is high and night temperatures stay warm during flowering.

Host crops and life cycle

The pathogen is seed-borne and also survives in crop residue and irrigation water. Outbreaks are triggered by hot, humid weather at heading, especially when night temperatures remain elevated. Excess nitrogen, dense planting and rank canopies aggravate the disease by raising in-canopy humidity.

Damage and economic impact

Severe outbreaks have been reported to cause yield losses up to 75%, with additional milling and headrice penalties because of grain discoloration. The disease is increasingly important in subtropical and tropical rice belts, including parts of southern India.

Management

  • Resistance: no fully resistant cultivars are currently available; only partial resistance has been identified, so variety choice provides limited protection.
  • Chemical: chemical control is widely regarded as ineffective; copper-based sprays and oxolinic acid offer only marginal suppression.
  • Biological: seed and foliar treatment with Pseudomonas protegens and Bacillus spp. has shown promise in published trials.
  • Cultural: avoid late-season N flushes, widen spacing, and stagger planting dates to keep flowering windows out of peak heat-humidity periods. Seed treatment and rotation reduce inoculum carryover.

See also: Bacterial Leaf Blight Paddy, False Smut Paddy, Paddy Blast Disease, Paddy Sheath Stem Rot, Paddy Panicle Stage Management.

References

  1. Ham J. H. et al. Bacterial Panicle Blight and Burkholderia glumae: From Pathogen Biology to Disease Control. Phytopathology (American Phytopathological Society).