Symptoms
Oval greenish-grey water-soaked lesions on the leaf sheath near the water line that enlarge with irregular brown margins. Lesions climb up the plant in dense, over-fertilised stands and can cause lodging.
Prevention
Avoid excessive nitrogen and overly dense planting; both favour the disease. Maintain good drainage, balanced potassium, and clear weed hosts on bunds.
Treatment
Organic
Apply Trichoderma or Pseudomonas fluorescens to the soil and seedlings. Drain the field intermittently to reduce humidity at the plant base.
Chemical (last resort)
Apply hexaconazole, validamycin or a propiconazole-based fungicide at early lesion stage and at booting. Rotate groups and observe PHI.
Affects 1 crop
Sources
MARDI Rice Disease Guide; DOA IPM Manual