Yellow suckling clover identification and control

Yellow suckling clover Trifolium dubium

Also known as Lesser trefoil it is an annual weed that is a member of the clover family.  Sometimes confused with Black medic (Medicaga lupulina) to which it looks very similar, the only difference being that the seed pods of black medic turn black at the back end of the season

Appearance

Miniature clover-like leaves, each with three leaflets, are borne on short stalks.  On very close inspection the leaves are also toothed at the edges but this can be very difficult to see.

Leaf size comparison

Clusters of self-pollinating flowers are produced throughout the summer (May-September). The flowers, which are usually about 12 mm in diameter, are a vivid yellow turning brown later in the season.

Growth habit

Yellow suckling clover has a central taproot from which creeping runners (stolons) spread to form a dense, low-growing mat over the surface of the lawn that, eventually chokes out and smothers the grass if left unchecked.  Also reproduces by seed.

Trifolium dubium

Conditions that favour its development

Will grow in almost all soil types but tends to favour non-acidic, nutrient deficient soils, typical of dry sandy rootzones where its ability to fix nitrogen from the atmosphere gives it a competitive advantage.

Cultural control

Ensure that turf is strong and healthy.

• Remove small plants by hand before they become too widespread.
• Ensure that grass plants receive adequate nutrition, applying a suitable lawn fertiliser at regular intervals throughout the growing season to create a dense, healthy sward to minimise spaces for weed invasion and to maintain competition against the clover.
• Avoid fertilisers containing phosphorous that can favour the growth and development of clover.
• Rake the clover plant into an upright position prior to mowing to help maximise the amount of plant material being removed and help weaken it. Always box-off clippings to retain plant debris and seeds.
• Mow regularly and at an appropriate cutting height for the conditions to remove flower heads prior to the clover setting seed and to maintain turf density. As yellow suckling clover is an annual, reducing the amount of seedheads will prevent it returning in subsequent years.

Chemical control

Yellow suckling clover is more difficult to control using selective herbicides compared with white clover, however, it is still possible to control with a single application if applied correctly.

For best results opt for products containing the active ingredient mecoprop-p which have proven to be the most effective against plants in the clover family.

Always apply in strict accordance with the manufacturer’s instructions and when the grass and weeds are growing strongly (usually April-September).