Divisi
Leaf blotch
· Fungal
Photo: Clemson University - USDA Cooperative Extension Slide Series · CC BY 3.0
Leaf blotch is a fungal leaf disease of wheat and barley. It makes irregular light-brown to grey blotches on the leaves and leaf sheaths, spreading by rain-splashed spores from the lower leaves upward and from last season's leftover straw. It hits hardest in cool, wet seasons and can rob the crop of the top green leaves that fill the grain.
M. Fernandez-Gamarra et al. · CC BY 4.0 
Mary Burrows, Montana State University · CC BY 3.0
Why it matters
The top leaves of your wheat or barley are what feed the grain. Leaf blotch kills them from the tips down, and a bad attack in a wet season can take up to 40% of your harvest — nearly half. The tricky part is that once the fungus is spreading up the plant in warm, wet weather, sprays only protect the leaves that are still green — they cannot bring back a leaf that is already blotched and dying. That is why you must stop it early, before it climbs to the top leaves.
When to act
blotches appearing on the upper leaves during stem elongation to heading, especially in a wet season
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 leaf blotch field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to leaf blotch — 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 leaf blotch?
The damage you see first: small light-brown to grey blotches on the leaves, often with a yellow edge around them. They are not neat circles — they have ragged, irregular shapes, roughly the size of a grain of rice up to a thumbnail, and they start on the lower, older leaves first.
When should I take action against leaf blotch?
blotches appearing on the upper leaves during stem elongation to heading, especially in a wet season
How do I control leaf blotch?
Prevent it — start with a resistant variety (your strongest single tool): where you can, plant a wheat or barley variety bred to resist leaf blotch. A resistant variety slows the disease down more than any other prevention step, so fewer blotches form even in a wet year. Ask your seed supplier or extension officer which local varieties hold up best.
Which crops does leaf blotch affect?
Among the crops covered here: Wheat.
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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