2 Weed of the Week: White Clover (Trifolium repens)

Weed of the Week: White Clover (Trifolium repens)

By Laurence Gale

What is a weed? By definition a weed is a plant that is growing in the wrong place. Weeds take valuable space, water, sunlight and nutrients that may otherwise be accessible to important crops, in our case turf grasses. Weeds not only compete for these resources they can disfigure and cause problems to playing surfaces.

Weeds are very good competitors and take advantage of any opportunities to colonise turf situations, particularly when the sward is under stress and weak, leaving bare soil areas for weeds to populate. Weeds have many mechanisms and characteristics that enable them to do this, having thick waxy cuticle leaves that can be resistant to some chemicals, fast reproduction methods, the ability to reseed in 6 week cycles and deep tap roots enabling the weed to survive in compacted dry ground conditions.

Weeds have one of three life cycles: annual; biennial or perennial.

  • Annual weeds: Live for a single season. These weeds germinate from seed in the spring or summer, flower and then die.
  • Biennial weeds: Live for two seasons. During the first growing season, these weeds remain in a vegetative stage and, in the following year, produce flowers, set seed and die.
  • Perennial weeds: Live for multiple seasons and flower more than once. Perennial structures (rhizomes, stolons, crowns, entire plants or roots) survive from year to year.

Some weeds may be harmful to the environment or noxious to your regional ecology. For example Japanese Knot weed (Fallopia Japonica) is fast becoming a major weed problem on road side verges and urban landscape areas, a very difficult weed to eradicate. It is very important to recognise weeds and seek effective controls methods to eradicate them from our facilities.

Weeds can also be used as an indicator of soil conditions. For example, knotweed and plantains both indicate soil compaction because they can maintain adequate root respiration at lower oxygen diffusion levels than other plants. Different weeds tolerate different soil conditions, some are alkaline loving and others acid loving. Getting to understand and recognise the physiology of these plants will help you become better turfgrass managers.

This week's weed is: Trifolium repens (White clover)

Scientific name

Family

Life cycle

Common name

Trifolium repens.

Fabaceae, pea

Perennial

White clover

Form / Appearance

White clover (Trifolium repens L.) is a short-lived perennial that can reseed itself under favourable conditions. It grows rapidly and spreads via stolons. Clover has leaves that are usually palmately to semi-pinnately, divided into 3 leaflets. The leaflets are entire or shallowly toothed. Stems are low-growing, prostrate, usually without hairs but sometimes with short hairs, ranging from 100-400mm in height. Stems root at the nodes. The trifoliate leaves and white flowers are both key features that help in the identification of white clover.

clover-pic.jpg
Roots A fibrous root system with stems that root at the nodes. White clover has a shallow root system, which makes it intolerant of droughty soils. It grows best during cool, moist weather on well-drained, fertile soils with a pH between 6 and 7.
Flowers The clover family has flowers in mostly dense, rounded clusters, with colours ranging from white, yellow, or pink to red or purple. Trifolium is fertilized through pollination by insects such as the honeybees and bumblebees. clover-flower.jpg
Leaves Leaves are composed of 3 leaflets (trifoliate). clover-leaf.jpg
Reproductive method The fruit is a legume, round to elongated, usually shorter than, and included within the calyx, not splitting, with 1 to several rounded seeds.
Habitat This weed occurs in most turf grass situations especially in moist, low-fertility soils throughout growing season cloverwclover1.jpg
Miscellaneous info There are nearly 300 species of clovers worldwide, mostly of the N. Temperate Zone, especially in Western N. America, less abundant in S. America and Africa. The word Trifolium means three leaflets on each leaf.
Cultural Control Established clover colonies are difficult to remove by hand. Care should be taken to assure that all roots are thoroughly removed. Close mowing prevents seed head formation, whilst maintaining a dense sward will deter or prevent clover from establishing. Good soil fertility is essential, maintaining a soil pH of 6 to 7. clover-clump.jpg
Chemical Control Apply selective broadleaf herbicides when plant growth is active. There are a number of products available for controlling broad leaf weeds in established turf.

These chemicals are best used when the weeds are actively growing, usually between April-October.

  • Tritox (Contains 178g/L (16.2%w/w) MCPA 54.g/L(4.9%w/w) mecoprop-p and 15g/L (1.4%w/w) dicamba and potassium salts. Scotts.
  • Intrepid 2. (Contains 20.8g/L dicamba,166g/L dichlorprop-p ans 166.5g/L MCPA). Scotts.
  • Greenor. (Contains: 40g/L fluroxypyr, 20g/L clopyralid and 200g/L MCPA). Rigby Taylor.
  • Bastion T. (Contains: 72g/L fluroxypyr and 300g/L mecoprop-p ). Rigby Taylor.
  • Clovertox (Contains 142.5g/L(13% w/w) mecoprop-p as the potassium salt. Bayer Environmental Science.
  • Supertox 30(Contains 95g/L (8.8%w/w) mecoprop-p and 93.5g/L(8.7%w/w) as the diethanolamine salts). Bayer Environmental Science.

These herbicides are usually applied as a liquid using watering cans, knapsack sprayers and vehicle mounted sprayers.

Ensure you follow manufacturer's directions, health & safety and product data sheets, and comply with COSHH regulations, when using these chemicals.

Herbicides are an effective tool where high quality turf is desired. However, they must be applied with care and accuracy and in the context of a good overall turf management program. Before using any herbicide, carefully review the label for conditions of use including rates, methods of application, and precautions. Never use an herbicide in any manner contrary to its label and be sure that the herbicide will not injure the turfgrass species

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