In the monsoon my colocasia leaves develop water-soaked brown spots that spread fast and kill the leaves. How do I manage this taro leaf blight?
2 Answers
Fast-spreading water-soaked brown to black leaf spots in wet weather are typical of taro leaf blight (a Phytophthora disease), which is severe in high humidity and rain. Management is mainly cultural and preventive: use clean planting material, grow on well-drained beds, avoid waterlogging, give wider spacing for airflow, remove and destroy badly infected leaves, and rotate. Use tolerant varieties where available. If a protective fungicide is justified in a high-pressure season, use only a product labelled for this disease and crop and follow the label dose and pre-harvest interval, and confirm the current recommendation with your KVK or State Agriculture University since approvals change. Do not rely on spray alone, the drainage and clean material matter most.
In Nagaon the blight hits every monsoon. Raised beds and not crowding the plants made a big difference for me. I also pull off the first infected leaves quickly before it runs through the field.