Lawn Problems and How to Solve Them
Prevention is better than cure where lawn weeds, pests and diseases are concerned, since a thick covering of healthy grass with few bare patches will resist the onset of such infestations. It is also more resistant to prolonged drought. If your lawn looks more like a roadside verge, however, with weeds, toadstools, mole hills and moss patches, there are still many ways of renovating it to a bowling-green finish.
Controlling Lawn Weeds
Check surface-creeping weeds such as clover and yarrow by raking or brushing them upright before each mowing. This ensures that their leaves and stems are cut off by the mower blades. Some annual weeds, such as trefoil and mouse-ear chickweed, may also be controlled to some extent by this treatment.
Use the grass box when mowing, and destroy the clippings —they invariably contain weed seeds and fungal. Isolated weeds can be removed by hand before they develop into a serious infestation. Use a daisy grubber or small hand fork and try to remove as much of the root system as possible intact, since broken sections of root often regrow, especially those of dandelions and thistles. Selective weedkillers, in the form of powders or liquids, are effective against most weeds. They are best applied in late spring to mid summer, but can be used up to early autumn
Apply a lawn fertilizer a fortnight before the weedkiller to give the grass an extra boost. Mow the lawn two or three days before applying the weedkiller and try to pick a warm, still day for application, when the grass is dry and thebelow it is moist. Follow closely the manufacturer’s recommendations for application rates and timing.
Chemicals frequently used for lawn weedkillers include 2,4-D, dicamba, dichlorprop and mecoprop. Often two or more of these chemicals are combined as ‘cocktails’, giving a more thorough weed-killing action, They may be formulated as concentrated liquids, soluble powders, granules or foams
Selective weedkillers are based on a hormone substance which over-stimulates weed growth, causing the leaves to twist and curl. Finally, the weeds die and rot away. The amount of hormone absorbed by the grass is not enough to do any harm — grass leaves are narrow with a waxy surface and a longitudinal channel-like mid-vein, so liquids tend to run off the surface before they are absorbed.
Do not mow the lawn for at least three days after using the weedkiller. Compost the clippings for at least six months before using them to allow time for the weedkiller to decompose completely.
Weedkillers can be bought as combined formulations with lawn fertilizers, though the weedkiller may be slightly less effective than when applied after a fertilizer. Spot weedkillers can be used to treat isolated weeds in a lawn. Nowadays, the most popular spot weedkillers are formulated as foams and are sold in aerosol cans. Spray the chemical directly on to the crown of each weed. The active ingredient is usually 2,4-D with dicamba.
Lawn sand preparations are also available as alternatives to hormone weedkillers for controlling daisies and other broad-leaved weeds. Lawn sand is also an effective moss killer, though special moss killers give more long-lasting control.
The chemical ingredients of lawn sand are sulphate of ammonia and sulphate of iron. Mixed with sand, these have a corrosive effect on broad leaves, but are absorbed to a much lesser extent by the narrow-leaved grasses.
Apply lawn sand in spring or early summer, Follow the manufacturer’s instructions and do not overdose. The best time is when the grass is moist with dew and the soil damp.
Water the lawn if rain has not fallen after two days. After three weeks, rake up dead undergrowth.
Apply a further dressing of lawn sand if necessary.
Temporary blackening of the older grass often occurs. However, once the chemicals have been washed down, the grass will recover rapidly.
Other Lawn Problems
Broad-leaved weeds are by no means the only causes of lawn problems. Certain pests and diseases attack even the best-kept lawns.
Algae may appear in damp turf. These simple plants are usually black, slippery and jelly-like. Spike the lawn to improve, then apply a mercurized lawn sand, sulphate of iron or copper sulphate. Top-dress and feed the lawn to build up the grass’s strength.
Ants make small hills of soil as part of their nest-building activities. These are most frequent on sandy soils and generally appear in summer. Brush off the soil hills before mowing. Dust the affected area with a proprietary ant destroyer or place gel-type ant baits around the nests.
Chafer grubs may kill small patches of turf by gnawing at the roots in spring and summer The grass turns brown in colour and breaks away from the surface. Roll the lawn in spring to crush the grubs. Earthworm and leather-jacket control measures also destroy chafer grubs.
Dogs, especially bitches, urinate on lawns causing scorching —grass turns yellow, then brown. Once killed, the grass must be dug out and replaced, but isolated troubles can be avoided by flooding with water immediately to-dilute the urine.
Earthworms push small, irregular mounds — casts — of soil to the surface. On heavy soils, and when flattened down hard by walking or by the mower roller, these can stifle the smaller grasses and make an uneven surface.
Remove worm casts by regular sweeping. Fewer large cast-forming worms are found in acid soil, so dressing the lawn with sulphate of ammonia, sulphate of iron and organic substances such as leaf-mould will help to prevent this trouble. In severe cases, apply a worm killer, such as chlordane, according to the manufacturer’s instructions.
Leatherjackets cause yellowish patches in a lawn, and damage may be more extensive after a wet autumn. These pests are the grubs of crane flies — daddy-long-legs. Improve the drainage of the soil and dust with HCH.
Moles can ruin a lawn by excavating large heaps of loose soil. These are joined just under the turf by long, interlinking tunnels. The tunnels, leading to the nest chambers, sometimes collapse, causing sunken channels across the lawn.
Eradication of moles is rarely successful unless carried out by a professional mole catcher, and I can tell you this from personal experience. Traps and poisons are the most effective means, but smoke pellets placed in the runs may deter some moles.
Moss is a common enemy. It is a symptom of run-down turf, primarily associated with over-compacted soil, poor drainage, excess shade and under-feeding. Dichlorophen is the most effective chemical for moss control and may be bought as a liquid concentrate or ready-to-use spray.
Apply moss killers in spring and autumn. Rake out the dead moss a few weeks later and re-seed any bare patches — moss infestations often take over entire areas of the lawn. Keep the remaining grass in good condition by feeding in spring. Avoid cutting the lawn too closely since this weakens the grass, allowing low-growing mosses to thrive. Lawn sand also burns out moss at the same time as boosting the grass.