Divisi
Turcicum leaf blight
Exserohilum turcicum · Fungal
Photo: Chroanch · CC BY-SA 4.0
Turcicum leaf blight (also called northern corn leaf blight) is a fungal leaf disease of maize and sorghum. The fungus survives the dry season on old maize stalks and leaves lying in the field, then wind and rain-splash carry its spores onto the new crop. In cool, wet, humid weather (18-27C with long dews or drizzle) it spreads fast, killing the green leaves the plant needs to fill its grain.
Jerzy Opioła · CC BY-SA 4.0 
Wanich Khampanich, Department of Agriculture, Thailand · CC BY 3.0 au
Why it matters
This disease eats the green leaves that feed your grain, and once the plant is losing its leaves during cob-filling a heavy attack can cost you up to half your harvest (50%). It is hard to stop once it takes hold because the fungus is already living on old maize trash in your field, spores blow in from far away, and by the time the leaves look badly scorched the damage to your yield is largely done. Your best defence is set up before the disease is bad, not after.
When to act
Lesions appearing on leaves below the cob before or at tasselling, especially in a susceptible variety under wet weather.
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 turcicum leaf blight field guide
- Identify it
- Scout for it
- Control it
15 field-guide sections in the app
The full guide to turcicum 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 turcicum leaf blight?
The first thing you see: long, narrow spots on the leaves shaped like a cigar or a canoe — pointed at both ends, roughly the length of your finger (2-15 cm). They start grey-green and watery-looking, then dry to a pale tan or straw brown in the middle.
When should I take action against turcicum leaf blight?
Lesions appearing on leaves below the cob before or at tasselling, especially in a susceptible variety under wet weather.
How do I control turcicum leaf blight?
Prevent first — resistant variety (your strongest tool): plant a resistant or tolerant maize hybrid wherever you can. This is the most reliable and cheapest protection, because the plant fights the fungus for you and you may never need to spray. Ask your seed dealer or extension officer which hybrids resist leaf blight in your area.
Which crops does turcicum leaf blight affect?
Among the crops covered here: Maize, Sorghum.
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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