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Taro leaf blight
Phytophthora colocasiae · Fungal
Taro leaf blight (Phytophthora colocasiae) is the most damaging disease of taro. It is not a true fungus but a water mould — a germ that swims. In warm, wet weather it makes swimming spores that ride on splashing rain, dew and wind and reinfect fresh leaves within days, so a healthy field can be stripped bare almost overnight. It rides between crops on infected corms (the underground food store) and on stray volunteer taro plants.
Why it matters
Taro leaf blight is the number-one killer of taro. In warm wet weather it moves so fast it can strip your leaves in a matter of days, and once the leaves are gone the plant cannot feed its corm — a bad attack can cost you up to 9 in every 10 tubers (90%), and rot the corms you do dig up. It is hard to beat once it takes hold because it spreads invisibly in every splash of rain and drop of dew, and it hides in the soil on old corms and volunteer plants to strike your next crop. That is why stopping it starts before you see it — with a resistant variety and a dry, open canopy — not after.
When to act
Begin protective sprays and sanitation at the first water-soaked lesions, particularly in warm wet weather with a susceptible variety, because the disease can defoliate a crop within days.
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full taro leaf blight field guide
- Identify it
- Scout for it
- Control it
13 field-guide sections in the app
The full guide to taro leaf blight — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify taro leaf blight?
The first thing you see: small dark, water-soaked spots on the leaf — they look wet, greasy and slightly sunken, as if a drop of oily water soaked in. They often start at the leaf edge or tip where dew sits longest.
When should I take action against taro leaf blight?
Begin protective sprays and sanitation at the first water-soaked lesions, particularly in warm wet weather with a susceptible variety, because the disease can defoliate a crop within days.
How do I control taro leaf blight?
Prevent it first — plant a resistant variety (your strongest tool): grow a blight-resistant or tolerant taro variety. This is the foundation of control and works far better than anything you spray on later — a good resistant variety stops most of the disease before it starts.
Which crops does taro leaf blight affect?
Among the crops covered here: Cocoyam / Taro.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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