Symptoms
Small water-soaked spots on leaves that enlarge into large brown blighted zones with concentric rings, often dripping droplets of fluid in the morning. Severe blight destroys the whole canopy and rots the corm.
Prevention
Plant resistant cultivars and disease-free planting material with wide spacing for airflow. Avoid overhead watering and remove infected leaves promptly.
Treatment
Organic
Remove and destroy blighted leaves and apply a copper-based fungicide preventively. Improve airflow and avoid working among wet plants.
Chemical (last resort)
Apply metalaxyl plus mancozeb on a 7-10 day cycle during wet weather, starting before symptoms in high-risk seasons. Rotate groups and observe PHI.
Affects 1 crop
Sources
MARDI Taro Production Guide; DOA IPM Manual