Divisi
Striga (witchweed)
Striga hermonthica · Parasitic Weed
Photo: United States Department of Agriculture: Agricultural Research Service · Public domain
Striga, or witchweed, is a parasitic weed — a weed that lives by driving a sucker into the roots of a cereal crop underground and drinking off its water and food. Its dust-fine seeds lie in wait in the soil and wake up only when they sense the roots of a crop they can feed on; the young parasite then attaches below ground and bleeds the plant for weeks before it ever breaks the surface. Unlike most root parasites it does carry small green leaves and pretty pink-purple flowers, so above ground it looks like an innocent flowering weed standing between the crop rows — but a single plant sheds tens of thousands of seeds that stay alive in the soil for many years, so it builds up fast where maize, sorghum or millet are grown season after season on tired, low-nitrogen ground.
Ethan Bass · CC BY-SA 4.0 
Aneth David (SLU) · CC BY-SA 4.0
Why it matters
Striga is a parasitic weed (a weed that lives off your crop and gives nothing back) — it fixes onto your cereal's roots underground and drinks its water and food, so your plants starve from below while they still look like they are only growing badly. A heavy attack can take up to 80% of your harvest — as much as four of every five plants' worth of grain, and on the worst fields almost the whole crop. The cruel part is that most of the damage is done underground before you ever see the weed — by the time its purple flowers show between the rows, your maize is already robbed. And a single Striga plant left to flower drops tens of thousands of dust-fine seeds that stay alive in your soil for many years, ready to attack every cereal you plant, so beating it is a multi-season job of starving those seeds in the soil, not a one-time spray.
When to act
Any emerged Striga plants, or a known infested field; act pre-emptively because most damage is done underground before the weed emerges, and each plant sheds tens of thousands of long-lived seeds.
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 striga (witchweed) field guide
- Identify it
- Scout for it
- Control it
17 field-guide sections in the app
The full guide to striga (witchweed) — 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 striga (witchweed)?
The first warning, before you see the weed: a patch of crop that is stunted, yellowing and wilting in the afternoon heat even though the soil is still moist. The parasite is drinking your plant's water and food from below, so the crop shows a thirst and a hunger it should not have — leaves may redden or scorch at the edges, plants stay short, and cobs or heads fill poorly. It shows in spreading patches, worst on the poorest, driest parts of the field. Mark these weak patches — Striga is at work underground right there.
When should I take action against striga (witchweed)?
Any emerged Striga plants, or a known infested field; act pre-emptively because most damage is done underground before the weed emerges, and each plant sheds tens of thousands of long-lived seeds.
How do I control striga (witchweed)?
Best defence — feed your soil. Striga thrives on poor, hungry, low-nitrogen soil, so a well-fed crop is your strongest weapon: it attacks far fewer plants where the ground is rich. Work in manure or compost, add nitrogen, and a strong, well-fed cereal will shrug off Striga that would cripple a starved one. This is the single most important thing you can do.
Which crops does striga (witchweed) affect?
Among the crops covered here: Cowpea, Maize, Pearl millet, 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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