Weed Control Tips

Common turf weeds such as Lesser Trefoil can be difficult
to control at the best of times. However by following the
advice on this page, optimum results can be achieved

For gardeners who want a fine turf lawn that is weed free, then selective herbicides will at some point play a role in keeping the lawn free of broadleaved weeds. Although hand weeding is recommended, there comes a point when chemicals have to be used in the fight against weeds, to prevent them taking over the lawn.

When you reach this point and are ready to treat the weeds with a selective weed killer, then the advice below will help you get the best results.

Choose the correct weed killer

• There are various weed killers available for weed control, with most of the products containing at least 2 active ingredients. For example Product A may contain the ingredients 2,4-D + mecoprop-p and Product B may contain dicamba + MCPA + clopyralid. Certain weeds are more susceptible to certain ingredients, E.G. As White clover is very susceptible to mecoprop-p, choose a product that contains mecoprop-p. 
  
  Therefore it is advisable to do a little homework on the weeds you are treating, to find out what products contain the most effective ingredient/s for your situation.

Timing of weed control

• Weeds in the lawn should be controlled when they are actively growing. This is usually between April & September with the months of May & June being the ideal period, as growth during this time is usually at it strongest. Many turf care professionals apply a nitrogen based fertiliser a week or so prior to treating weeds to encourage growth.  This helps them get optimum results from weed treatment.

Weed Treatment

• Cut the lawn and then then leave it for 3 days (this will allow the leaf of the weed to grow back and it gives the spray a larger target area to stick to).

• Spray the selective weed killer

• Leave the lawn a further 3 days before mowing it (this allows the chemical to travel from the leaf into the whole plant, ensuring optimum results. Cutting the lawn, after application will remove much of the chemical before it has had a chance to travel into the weed, reducing the effectiveness.

• Always apply the weed killer when the lawn is dry as this helps the weed killer stick to the leaf. Spraying during damp conditions only causes the chemical to run off the weed and the results will be poor.

Avoid treating weeds during periods of drought as you may damage to your lawn.

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Doves Foot Cranesbill

Common name: Doves Foot Cranesbill

Botanical name: Geranium molle

Family: Geraniaceae

Life cycle: Annual

Habitat: Doves foot cranesbill prefers nutrient deficient, dry, free draining soil and is commonly found on waste areas and grassland.

Leaf: The leaves form in a rosette and are round in shape, with each leaf having 5 - 7 lobes. The surface is covered in fine hairs.

Flower: The small pink - purple flowers bloom from May to September.

Removal & control:  Hand weed individual plants before they become a problem.

Doves foot cranesbill is another weed that is difficult to remove with a selective herbicide, fortunately it is not common in managed turf.

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Common Sorrel

Common name: Common Sorrel

Botanical name: Rumex acetosa

Family: Polygonaceae

Life cycle: Perennial

Habitat: Common sorrel is common in most types of grassland. It will grow in most types of soil but prefers a low pH. It is a member of the 'Dock' family and is sometimes called the 'Garden Sorrel'.

Leaf: This weed has long, arrow leaves.

Flower: The flowers are borne on long spikes, initially they are a greenish red colour before they turn a purple colour.

Removal & control: If the weeds are few in number, then hand weeding my suffice, taking care to remove the root system. Regular mowing will help discourage and eventually remove common sorrel.

A difficult weed to control with a selective weed killer. In all most all cases more than one treatment will be required.

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Procumbent Pearlwort

Common name: Procumbent Pearlwort

Botanical name: Sagina procumbens

Family: Caryophyllaceae

Life cycle: Perennial

Habitat: Procumbent pearlwort will grow in most types of soil. It is particularly troublesome on turf that has suffered through being mown too short, as it tolerates very close mowing. This weeds forms as a low growing mat.

Leaf: The leaves are fine and narrow and they form a tightly knitted mat, often giving a moss like appearance.

Flower: Tiny white flowers bourn on short stalks can be seen between may and September.

Removal & control: If the plants are few in number then hand weeding can prove successful. Mow the lawn at a sensible height, as pearlwort will take advantage of thin or bare areas caused by very close mowing.

If a selective weed killer is going to be used for control then more than one application may be needed, as pearlwort can be a stubborn weed to remove.

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Yarrow

Common name: Yarrow

Botanical name: Achillea millifolium

Family: Asteraceae

Life cycle: Perennial

Habitat: Yarrow, sometimes called 'Milfoil' is a very common weed in fine turf. It favours light, dry, sandy soils that are often undernourished. It can be a good indicator that a soil is lacking in nutrients and needs feeding. Yarrow is very resistant to drought.

Leaf: The long, narrow leaves are fern like and feathery to touch. If they are rubbed together or crushed, they give off a strong fragrant scent.

Flowers: The white coloured flowers are borne in clusters. They are commonly seen between July and October.

Removal & control: Yarrow is a difficult weed to control, both culturally and with chemicals. Hand weeding may only be practical is the weed is low in numbers.

This weed is resistant to most selective weed killers and in almost all cases, further applications will be necessary. Even then success may be somewhat limited.

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Bristly Ox Tongue

Common name: Bristly Ox Tongue

Botanical name: Picris echioides

Family: Asteraceae

Life cycle: Annual or Biennial

Habitat: Bristly ox tongue is very common on waste areas, grassland and occasionally on lawns. In turf it forms as a lowing growing rosette type weed and will grow in most types of soil.

Leaf: The narrow lanceolate leaves are covered in swollen pimples of bristles (hence the name of this plant).

Flower: Bristly ox tongue produces multiple dandelion like flowers. The yellow flowers can be seen between June and September.

Removal & control: Individual plants can be removed by hand. Encourage a healthy lawn with adequate feeding and good lawn care practices.

A selective weed killer can be used, however a second treatment may be needed for complete control.

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Smooth Hawksbeard

Common name: Smooth Hawksbeard

Botanical name: Crepis capillaris

Family: Asteraceae

Life cycle: Annual

Habitat: Smooth hawksbeard is often found on roadsides, waste areas and grassy land. This rosette type plant will grow in most types of soil but prefers dry sites, especially on coastal sites.

Leaf: Dandelion type leaf that is long, narrow and heavily toothed.

Flowers: The yellow flowers are bourne on branched stems and cane be seen between June and September.

Removal & control: Hand weed taking great care to remove the whole plant including the long taproot.

If the infestation is severe then a selective weed killer may be needed for control. More than one application may be needed for effective control.

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