Divisi
Yam anthracnose
Colletotrichum gloeosporioides · Fungal
Photo: Glysiak · CC BY-SA 4.0
Yam anthracnose is the most damaging leaf-and-stem disease of yam, caused by the fungus Colletotrichum gloeosporioides. It carries over on old infected vines and crop trash, then splashes onto new leaves in rain. In the warm, wet weather it loves (25-30C with leaves staying damp for hours), it blackens leaves and stems, kills the growing shoots (dieback), and strips the vine bare so the plant can no longer feed the tuber underground.
Anto Rashwin · CC BY-SA 4.0 
USDA Forest Service · CC BY 3.0 us
Why it matters
Anthracnose is the number-one leaf disease of yam, and a bad attack in a wet year can take up to 70% of your harvest - more than two of every three tubers you were counting on. It kills the leaves and shoots that feed the tuber underground, so even though the rot is up top, the loss is felt at digging time as small, poor tubers. It is hard to beat once it takes hold because the fungus hides in old vines and dead leaves on the ground and comes back with every rain, so the only real win is stopping it before it settles in.
When to act
Dark leaf and stem lesions appearing on the vines during the rainy season, especially on a susceptible variety.
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 yam anthracnose field guide
- Identify it
- Scout for it
- Control it
19 field-guide sections in the app
The full guide to yam anthracnose — 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 yam anthracnose?
The first thing you see: small dark brown to black spots on the leaves, each about the size of a pinhead to a match-head. Look closely and many have a pale or yellowish edge around the dark centre.
When should I take action against yam anthracnose?
Dark leaf and stem lesions appearing on the vines during the rainy season, especially on a susceptible variety.
How do I control yam anthracnose?
Prevent first - grow a tougher variety (your strongest single tool): plant a tolerant/resistant yam variety and avoid the highly susceptible types in wet, humid zones. This is the most effective thing you can do because it slows the disease before it ever starts.
Which crops does yam anthracnose affect?
Among the crops covered here: Yam.
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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