Lawn Problems

Many lawns suffer from the presence of weeds and other lawn problems. The most common are listed below, click for more information.

  • Earth Worms

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    Earthworms have an important role in helping to aerate soils, reducing compaction, improving water penetration and infiltration rates, processing organic matter and reducing thatch. They surface under moist soil conditions (e.g. in late autumn and winter) and retreat downward in dry weather.

    However, some species of earthworms leave casts on the turf surface and this has many negative effects:

    1. Aesthetics
    2. Uneven surface levels
    3. Weed invasion more likely as casts may bring dormant weed seed to the surface or by wind blown seeds landing on casts and geminating
    4. Mole activity increase in proportion to worm populations

    Approach

    1. Reduce thatch in programmed approach to minimise food source for earthworms.
    2. Minimal use of organic amendments.
    3. Lower soil surface pH to discourage earthworm activity by using acidifying fertilizers.
    4. Encourage drier surfaces through aeration and verticutting etc.
    5. Minimise amount of clippings returned to soil (organic material) by use of slow release fertilizers and/or Plant Growth Regulators.
    6. Using a wetting agent with strong penetrant activity will ensure that moisture moves from the surface and down the soil profile and make surface casting less likely.

  • Fairy Rings

    fairyRingAlthough it is not always necessary or appropriate to control Fairy rings, they can be particularly troublesome on many different turf types. Decayed organic matter and high levels of thatch can favour disease development, usually caused by infrequent watering and fertilizer regimes.

    The rings of stimulated grass growth are the result of nitrogen released in the soil by the Fairy Ring activity under ground breaking down organic matter to release ammonia that is processed by soil micro-organism into nitrates.

    The 3 main types of Fairy ring:

    1. Marasmius oreades – ring of dead turf bordered by stimulated turf growth. Causes turf death by soil water repellence and/or toxic substances.
    2. Agaricus & Lycoperdon spp – stimulated grass growth with no fungal bodies. Rarely causes excessive damage to turf.
    3. Hygrophorus & Psilocybe spp – no affect on turf grass except when fruiting bodies are present (normally in autumn).

    Approach

    1. Try to minimise those conditions which favour disease development.
    2. Control thatch in a programmed approach.
    3. Apply wetting agents that have a penetrant activity will help to move water through the hydrophobic layer to help cure the symptoms of the disease.
    4. Wetting agents should be used in combination with deep aeration.
    5. To prevent spreading pathogen use solid rather than hollow tines.
    6. If required, Nitrogen fertilizers can be used to mask the visual symptoms of light and dark green rings.

  • Leatherjackets

    The adult Crane Fly has long legs with a body about 25mm long, commonly active in the late summer to autumn period with each female laying 200-300 eggs.

    The egg hatch into larvae, called a Leatherjacket, in about 14 days and remain in the soil for about 9 months before pupating into next season’s Crane Fly.

    The Leatherjacket exists in the soil from the autumn to the following spring on the turf and roots, biting off stems at or just below ground level resulting in the turf dying back often in clumps. Damage generally becomes noticeable during the spring caused by the feeding that occurred the previous autumn and winter. Secondary damage from birds, badgers, foxes, moles and other small mammals searching and pecking for larvae can rip up the turf.

    Approach

    1. Keep a look out for Crane Fly activity throughout the summer.
    2. Monitor the turf in the autumn for larvae activity and secondary damage.

  • Moss

    Mosses are normally found in cool, shady moist conditions, little soil is required by the moss for nutrient extraction. Turf with poor density is susceptible to moss infestation. Causes of poor density could be under fertilization, over-watering, scalping from mowing and shady conditions. Moss damages turf in terms of performance, aesthetics, and competition, creating vulnerability to wear and allow conditions for weed invasion.

    Approach

    1. The first strategy should be to create an environment, which is not naturally suitable for the growth of moss.
    2. Increase airflow and light.
    3. Increase water movement and infiltration, adjust irrigation practices to allow surface to dry out.
    4. Using wetting agents with a good penetrant activity will help to remove surface moisture.
    5. Ensure turf is healthy via good nutritional programme so that is has a competitive advantage over the moss.
    6. Use fertilizers containing ferrous sulphate will act directly upon the moss.
    7. Control thatch in a programmed approach.
    8. Once environmental conditions have been adjusted then use an approved Plant Protection Product.
    9. Physically remove dead moss through scarifying.

  • Red Thread

    Red Thread occurs mostly on turf where there is a low soil nitrogen level however, there are cases of nutrient independent Red Thread attacks. Light brown spots can be seen on turf, which have a reddish appearance. Compacted soils or conditions where poor rooting is likely can increase disease occurrence.

    Approach

    1. Red thread is an indicator of low nutrition, especially nitrogen.
    2. The first approach should be to prevent this situation arising by applying adequate nitrogen fertilizer as part of a programmed approach.
    3. Apply the correct fertilizer according to turf situation and height of cut.
    4. Aerate soil to encourage good root growth.
    5. Select resistance grass cultivars.

  • Shading

    Low light reduces photosynthesis which in turn reduces carbohydrate production and rooting. In low light conditions, plants naturally grow upwards in order to out compete other plants and capture more light. When the low light is caused by permanent shading (not caused by competing plants) then this can also cause etiolation, that causes long, stretched out growth producing weak plants.

    The causes of shading (trees/buildings) are also likely to reduce air movement therefore meaning the turf surface stays wet for longer meaning potential increase in disease occurrence. Turf growing in shade also has a thinner leaf cuticle which can make the plant more susceptible to disease attack.

    Approach

    1. Where possible manage the environment to reduce the amount of shade.
    2. Encourage the turf to grow without excessive vertical growth and encourage better rooting.
    3. Reduce nitrogen inputs versus full sun areas
    4. Reduce irrigation compared to full sun areas
    5. Dry surface with use of penetrant wetting agent
    6. Aerate well to encourage good rooting and movement of surface water
    7. Increase carbohydrate levels in plant.
    8. Select shade tolerant grass cultivars

  • Thatch

    Thatch is the organic layer below the green leaf material of the turf and above the soil itself. Excess thatch occurs when new tissue develops at a rate quicker than soil microbes can break it down. Thatch can hinder root development and provides a good environment for turf pathogens and insect pests. It also removes the buffering effect of soil on rapid changes of air temperature around the crown of the plant.

    Thatch becomes hydrophobic when it dries out and it can cause water holding problems. Over-seeding can be less successful if thatch creates a barrier between seed and soil.

    Approach

    1. Control should be via an integrated approach of cultural practices and sensible product use.
    2. Aerate to encourage soil microbial action
    3. Scarify to remove dead plant material
    4. Apply topdressing to dilute thatch
    5. Use correct levels of nutrition. Excess nitrogen will encourage thatch.
    6. Use the correct types of nutrition
    7. Wetting agents to aid water management
    8. Use soil biostimulants to encourage microbial breakdown of thatch
    9. Box off clippings to limit build up of dead plant material in soil.

  • Water-logging

    High rainfall events and winter flooding are becoming more common. The risk of water-logging and flooding are more likely due to a number of factors such as poor soil structure reduces water holding capacity of soil and poor ground cover increases potential for surface run-off.

    Approach

    1. Aerate the soil to encourage water infiltration.
    2. Select grass seed cultivars with improved root growth
    3. Encourage good rooting through good nutrition and managing soil structure.
    4. Ensure strong growing turf that will take up water efficiently,
    5. Use slow and controlled release fertilizers to avoid nutrient losses and to avoid the need for re-application in wet conditions.
    6. Raise height of cut prior to likely flood event to increase sward canopy and also to encourage deeper rooting.
    7. If possible, use cut off drains to protect sensitive areas.
    8. Contouring of surface levels (where possible) can help to control movement of water away from problem areas.
    9. Aerate the soil to encourage water infiltration.
    10. Encourage good rooting through good nutrition and managing soil structure.

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