Yellow wood sorrel (Oxalis corniculata)
A low, clover-like weed whose seed pods burst open and fling seed, common in coffee plantations.
- Type
- Broadleaf weed (creeping, mat-forming)
- Life cycle
- Perennial; regrows from roots and spreads by seed
- Spreads by
- Seed pods that burst and fling seed; also creeping stems
- Main harm
- Forms a spreading mat that competes with young plants
Overview
Yellow wood sorrel (Oxalis corniculata) is a low, creeping weed with three heart-shaped leaflets on each leaf, similar in shape to a small clover, and small, five-petaled yellow flowers. It has a sour taste if chewed, which is where common names like "sour grass" come from in some areas. It is common in coffee plantations and other shaded, moist ground.
Its slender, upright seed pods burst open when touched or ripe, flinging tiny seeds away from the plant, so timing its removal before the pods form matters more than for most weeds. It also regrows readily from root and stem fragments, so shallow hoeing that leaves pieces behind does not fully remove it.
How to identify it
- Low, creeping plant with three heart-shaped leaflets on each leaf, similar in shape to a small clover.
- Small, five-petaled yellow flowers.
- Slender, upright seed pods that burst open when touched or ripe, flinging tiny seeds away from the plant.
- Has a sour taste if chewed, which is where its common name "sour grass" comes from in some areas.
Why it is a problem
- Forms a spreading, mat-like ground cover that competes with young coffee plants for nutrients and moisture.
- Its seed pods burst open and fling seed a good distance, so a small patch can spread across a plot faster than most weeds.
- Regrows readily from root and stem fragments, so shallow hoeing that leaves pieces behind does not fully remove it.
- Tolerates regular mowing or light weeding better than many broadleaf weeds, so it can persist under routine upkeep.
Cultural & preventive control
- Hand-pull it carefully before the seed pods form or ripen, since ripe pods burst at the slightest touch and scatter seed.
- Mulching around young coffee plants suppresses it well and reduces how much light reaches the soil for it to establish.
- Remove pulled plants from the site rather than leaving root or stem fragments on moist soil, since these can regrow.
- Repeat removal through the season, since a single weeding round is rarely enough for a persistent, low-growing weed like this.
Herbicide control
- Herbicide use in coffee is limited because of the crop's shade requirements and sensitivity, so hand removal and mulching are the main methods.
- Where a spot herbicide is used between rows, keep it well away from young coffee plants and the root zone.
- Confirm any herbicide product suitable for use around coffee with your local KVK before spraying.
Integrated management
- Mulch well, hand-pull before seed pods form, and repeat through the season rather than expecting one weeding round to finish it.
- Handle pulled plants carefully near ripe pods, since disturbing them can scatter seed exactly where you are trying to clear it from.
- Combine this with the coffee plantation's normal shade-canopy management, since a well-closed canopy eventually shades out much of the ground weed growth on its own.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
What is this low, clover-like weed with yellow flowers in my coffee plot?
A low, creeping weed with three heart-shaped leaflets per leaf (similar in shape to clover) and small yellow, five-petaled flowers is yellow wood sorrel (Oxalis corniculata). It has a sour taste if chewed, which is where common names like "sour grass" come from. Its seed pods burst open at the slightest touch and fling seed some distance, so pulling it before the pods ripen matters more than for most weeds.
Why does this weed keep spreading even though I weed regularly?
Its seed pods burst open on their own or at the slightest touch, flinging tiny seeds a good distance from the parent plant — so a patch you missed by even a few days can reseed a wider area before you notice. It also regrows from root and stem fragments left behind by shallow hoeing. Pulling it carefully before the pods form, and mulching to suppress new growth, works better than routine light weeding alone.
Should I use a herbicide against this weed in my coffee plot?
Herbicide use in coffee is generally limited because of the crop's shade needs and sensitivity, so hand-pulling before the seed pods form and good mulching are the main effective methods. If a spot herbicide is used between rows, keep it well away from coffee plants and their root zone, and confirm a suitable product with your local KVK first.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.