Pests & Diseases


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Overseeding with species such as Bents or Fescue is commonly undertaken in the spring and autumn to break up the


dominance of Annual Meadow-grass


growth when the disease pressure is high. When approaching autumn, it is advisable to use slow release forms of fertiliser. Use iron prudently to harden plant cells off and make them less susceptible to disease. Though care must be taken when applying iron in the form of iron sulphate, as swards that are dominated by Annual Meadow-grass tend to have received an abundance of fertilisers that contain a high proportion of ammonium sulphate. High levels of sulphur can lead to "black layer". Black layer is a deposit of metal sulphides caused by the activity of anaerobic bacteria. The anaerobic bacteria produce hydrogen sulphide which is highly toxic to turf.


Because Fusarium can survive within the


thatch layer, it is good cultural practice to minimise this layer through aeration. Monitor thatch levels and aerate to achieve desired levels of oxygen within the sward. Air flow over the turf can also help reduce the incidence of disease. Drainage will help facilitate the flow of moisture away from the


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surface. Regular topdressing can help dilute existing thatch levels, however heavy applications of topdressing are to be avoided as this can engender stress which can lead to an outbreak of Fusarium.


Biological Methods Of Control


Biological fungicides have been shown to suppress diseases that can occur in turf. Research has shown that biological controls can be effective in suppressing certain turfgrass diseases when used on a preventive basis, but they have not been shown to effectively control turf diseases on a curative basis or when conditions are conducive to severe disease development.


Chemical Methods Of Control Professional Fungicides


An array of fungicides has historically been used, although this armoury has been reduced in recent years as products have been taken off the market. There has also been an increase in disease resistance due to


the over-reliance upon specific groups of fungicides. Therefore, it is useful to adopt a strategic approach when utilising fungicides to derive the best use for what is a relatively expensive resource. Consider utilising good cultural practice to minimise reliance upon fungicides, the code of practice states that you should “ask yourself whether you need to use a pesticide or whether there is another method of control or combination of methods you could use”. Appropriate use of the correct fungicide at the most effective time will minimise the potential damage done by Fusarium. Fungicides target Fusarium at different stages and use different modes of action.


Preventative


Preventative fungicides are particularly effective at inhibiting Fusarium before it becomes firmly entrenched. Where a history of disease exists and the potential for disease is high, preventative fungicides can be used to stop Fusarium becoming a problem. This can


Implementing fertiliser and aeration


programmes that favour species such as Bents and Fescues is necessary in order to ensure they are favoured over Annual Meadow-grass


Outbreak any time of the year when conditions are favourable - warm temperatures, slow growth, adequate moisture, heavy dews, light rain or fog


Growth and reproduction of pathogen fungus in dead or infected grass begins to grow


Dormant period - sclerotia remain dormant until


conditions are favourable


Sclerotia (red threads) produced in dead and infected tissue


Infection - damaged grass tissue, discolouring and death


Grass infected with mycelium is dead within two days


stomata spread over leaves or stems, binding them together


Anthroconidia produced on dead tissue


Wind and water spreads the spores


Dissemination of pathogen carried to uninfected grass by foot traffic, equipment, animals - adheres to leaves when temperatures and moisture conditions are favourable


124 I PC FEBRUARY/MARCH 2017 Infects living plants through


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