Divisi
Groundnut rust
Puccinia arachidis · Fungal
Photo: LandCare Ltd., New Zealand · CC BY-SA 3.0
Groundnut rust is a fungal disease (Puccinia arachidis) of groundnut that raises small orange-brown blisters (pustules) on the leaves. Each pustule bursts to release rusty, wind-borne spores that ride the wind to fresh leaves and multiply fast in warm, humid weather. Badly rusted leaves dry up and hang dead on the plant, so the crop cannot fill its pods. It usually travels together with late leaf spot, and the two together do the most damage.
LandCare Ltd., New Zealand · CC BY-SA 3.0 
LandCare Ltd., New Zealand · CC BY-SA 3.0
Why it matters
Groundnut rust eats away the green leaves your plant needs to fill its pods, and a bad attack can take up to half your harvest (50%) — fewer, shrivelled nuts and useless dry haulm (the leafy stalks you feed to livestock). Once the orange pustules are spreading up the plant they throw out clouds of wind-blown spores, so it jumps from plant to plant and field to field within days. That is why it is almost impossible to "cure" a field that is already covered — the only real win is to catch it on the lower leaves and act before it climbs.
When to act
First orange rust pustules found on lower leaves during pod development, particularly under warm humid conditions.
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 groundnut rust field guide
- Identify it
- Scout for it
- Control it
13 field-guide sections in the app
The full guide to groundnut rust — 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 groundnut rust?
The first thing you see: turn a lower leaf over and look at the underside. Rust starts there as tiny orange to reddish-brown raised bumps (pustules) — like flecks of rust or brick dust, each smaller than a pinhead. Rub one with your thumb and an orange powder comes off on your skin — that powder is the spores.
When should I take action against groundnut rust?
First orange rust pustules found on lower leaves during pod development, particularly under warm humid conditions.
How do I control groundnut rust?
Prevent it first (your strongest, cheapest defence): plant a rust-tolerant groundnut variety — many also resist leaf spot, so one good seed choice fights both. Use clean, healthy seed, and don't plant a new crop right beside an older, already-rusted groundnut field.
Which crops does groundnut rust affect?
Among the crops covered here: Groundnut.
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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