White Clover

Biology

White clover a perennial broadleaf weed, that thrives across the United States. Its seeds germinate in moist-cool conditions during spring, early summer, or early fall. Additionally it adapts well to close mowing. It grows in various soil types. This adaptability makes it a common presence in Indiana lawns. Opinions vary: some consider it a weed. As highlighted in this weed of the month series. While others value its role in turf ecosystems.

Identification

White clover spreads through lawns in mat-like patches. Using low-creeping stolons that grow up to 18 cm per year. Its stems may be smooth or have sparse hairs. The leaves, usually in groups of three. Sometimes form a ‘shamrock’ or ‘4-leaf clover’ shape when a fourth leaf appears. These predominantly egg-shaped leaves have a grayish-green underside. a bright-green top, and A distinctive gray-green splotch or watermark at the base. The plant produces white flowers. Often with a pink tinge, in rounded, aggregated heads that can contain up to 85 flowers. White clover seeds have extremely hard coats.

Cultural control

Implementing cultural practices such as increasing mowing height, providing adequate irrigation, and overseeding to boost cool-season turf density and vigor can help lawns outcompete white clover infestations. Since white clover, a legume, can fix its own nitrogen, applying adequate nitrogen fertilizer often reduces clover and promotes a more competitive turf.

In terms of biological control, no specific methods target white clover. However, some organic postemergence herbicides, like pelargonic acid (Scythe) and acetic acid (in 5% or greater solutions), can manage weeds. Eugenol and other products containing medium-length fatty acids and clove oil have shown potential as effective weed control tools. But, as these organic herbicides are non-selective, they should only be used for spot treatments directly on weeds. Most of these herbicides have limited turf applications and are more suitable for areas like parking lots, fence rows, and bare-ground spaces.

Many new organic products include essential micronutrients, such as iron HEDTA (FeHEDTA), as active ingredients. These require multiple applications and generally reduce turf injury, sometimes even darkening the turf, but their long-term weed control efficacy is not well-documented.

For chemical control, typically involves a postemergence approach rather than preemergence, due to the limited availability of preemergence herbicides for broadleaf weeds in cool-season turf and the variable germination times. The most effective selective herbicide strategy involves repeated applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP. Products containing clopyralid, dicamba, florasulam, MCPP, and quinclorac should also provide effective control in cool-season turf.”