Symptoms
Diamond-shaped (spindle) lesions with grey centres and brown margins on leaves. Infected nodes blacken and snap; neck rot at the panicle base causes whiteheads and empty grain.
Prevention
Plant resistant varieties and avoid excessive nitrogen. Keep good field drainage, maintain wider spacing for airflow, and destroy infected stubble after harvest.
Treatment
Organic
Apply silicon (rice husk ash) to strengthen leaf cuticle. Spray Trichoderma- or Pseudomonas-based biocontrol and remove infected debris promptly.
Chemical (last resort)
Apply tricyclazole or isoprothiolane at early symptom onset and again at booting. Rotate fungicide groups and observe the pre-harvest interval (PHI).
Affects 1 crop
Sources
MARDI Rice Disease Guide; DOA IPM Manual