Managing turf disease through effective ITM
By Simon Elsworth, Head of Syngenta Professional Products
An outbreak of turf disease can ruin all the hard work put into preparing the best possible playing surface for any sporting event - be it the perfect greens for a prestigious golf tournament, or the pitch for a crucial cup game. Integrated Turf Management (ITM) has an essential role in countering turf disease, through a carefully controlled combination of nutrition, irrigation and maintenance.
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Turf disease problems are undoubtedly on the increase for all turf managers:
Turf disease issues are being exacerbated by:
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Some turf managers and agronomists refer to ITM as an ‘Art’, inferring a level of mystery with little science or technical skill involved. In reality, it takes a greater level of knowledge of all the facets of turf management, and a better understanding of the way they interact - combined with the best practical know-how of the turf manager - to make ITM work effectively.
The fact is that turf quality which was judged as fine by players 10 years ago, would be deemed unacceptable by many today; every golfer wants to play on Augusta quality greens and every footballer on a Premiership pitch - 365 days a year. The pressures placed on turf - and those responsible for its management - have increased accordingly. Furthermore, in many instances, there appears to be limited understanding among greens’ committees and club managers of all the aspects that can contrive to damage turf quality through disease.
The Turf Disease Triangle
The incidence of turf disease will be affected by:·
- Environmental conditions·
- Disease pathogens present·
- The type of turf
All three factors must be present and, with an ITM plan, turf managers must decide which of the factors they can successfully influence to redress problems more effectively, and where the role of fungicides can be most effectively employed to minimise the impacts on turf quality.
The Environment
If environmental conditions are not suitable - if it is too cold or too dry, for example - disease development will be slower, or may cease altogether. Managers must also recognise that turf stress brought on by environmental conditions, such as drought or water logging, can also make turf more susceptible to disease attack.
The weather is the primary factor in the equation and, for the most part, is outside the turf managers’ influence. However, detailed weather forecasting can predict when disease will strike and can enable managers to tailor turf management and fungicide application programmes to prevent damage. The web site www.greencast.co.uk gives local disease forecasts and weather information to support the implementation of an ITM plan.
Furthermore, there are management practices that will influence the local environmental conditions and may, where practical, be adjusted by turf managers, such as
- Irrigation
- Drainage
- Turf nutrition
- Mowing height
- Maintenance programmes
Recognising where there are environmental weaknesses can help predict where disease may be a greater problem, such as a shaded green that lies damp for most of the day that will be more susceptible to Fusarium Patch, for example. Although it may not be practical to cut back surrounding trees for aesthetic reasons, it may be a focus for remedial drainage work, to sweep off dew first each morning and to treat as a priority with Heritage or Banner Maxx as a preventative fungicide if disease is forecast.
Turf managers do also need to understand the environmental conditions which favour each individual turf disease pathogen. Alleviating the conditions conducive to Fusarium, for example, may make the turf more susceptible to Anthracnose.
The Disease Pathogens
Detailed analysis of most fine turf situations will reveal many of the primary disease pathogens are already present in the thatch or basal leaves - awaiting the right environmental conditions to break out. The role of ITM is to minimise the conditions that will enable that to happen. However, disease can also spread from outside sources. Domestic lawns, roadside verges and untreated amenity grass areas can all give rise to aerial infections.
Effective use of fungicide programmes will assure high quality turf in the short term by suppressing the disease pathogens. It will also reduce the disease pressure and the sources of inoculum to enable ITM practices to work more effectively in the long term.
For effective treatment, turf managers must be able to identify the target pathogen and understand the best route for its control - both in the selection of the appropriate fungicide and its application timing, as well as the optimum ITM solutions. The web sites www.greencast.co.uk and www.theturfdiseasecentre.co.uk provide excellent identification and advice guides for ITM plans.
The Turf
The composition of the turf - in terms of grass species and variety - is a key factor in the susceptibility to disease. However, disease is only one element of turf management, and other attributes of the turf use will be the primary factors in selection. In the short term, it will be a matter of managing the turf that is there, although in the longer term it may be possible to change the composition of turf through seed and management.
For most high quality golf and bowling greens, Bent grasses and fescues provide the most consistent playing surfaces and the inherent disease and stress resistance will have an important role in maximising the success of ITM strategies. Whilst they have proven difficult to maintain at the low cutting heights required to achieve satisfactory ball speed on many soil types, the advent of the PGR Primo MAXX to achieve better quality turf at raised cutting height could further extend the attraction of fescues and bent turf.
Poa annua is found in many fine turf situations and, with the right management, can produce outstanding quality playing surfaces. However, Poa is generally far more susceptible to disease attack, which can be made worse with heavy play and low cutting height.
Rye-grass provides the most hard-wearing, resilient sports turf surface of immense value in an ITM regime, but has traditionally proven difficult to create a high quality tight-cut surface. New varieties which can be cut down to 5mm may increase the attractiveness, but will still require intensive management and nutrition to maintain quality; turf managers introducing its use will have to alter their management plans accordingly.
The Role of Fungicides
ITM can help to minimise the effects of disease, but in many practical situations it can not eliminate the problem sufficiently to maintain high quality turf all year round. Fungicides remain a key component of turf disease control within an ITM programme. A good ITM plan will, however, help to achieve the best results from any fungicide application, as well as extending the length of time of protection - which could help to reduce the total number of fungicide applications required over the course of the season.
The key elements of fungicide selection are product choice and application timing. For product choice, the aim is obviously to select a fungicide that will give good control of the primary target pathogen. Secondly, since there will be a number of pathogens present at lower levels, an effective broad spectrum fungicide will help reduce the level of other diseases. An application of Heritage in July where Anthracnose is a problem, for example, will also control Take-all, Leaf Spot, Brown Patch, Rust and Fairy Ring that may occur at the same time, as well as reducing any Fusarium Patch that could flare up when conditions turn cool and wet in the autumn.
More recently, with the advent of more effective preventative fungicides, ITM plans have begun to look at fungicide application prior to disease symptoms breaking out, which can provide better results from lower inputs of modern products with lower environmental impact, and avoid issues of visible damage. U
tilising the knowledge of how different fungicides physically work on the developing fungicide pathogen, STRI trials have shown the best turf quality can be maintained by well-timed applications of Heritage after disease has landed on the turf leaf, but before it has had the chance to germinate and penetrate into the plant. Later applications still have curative activity and will stop disease sporulating and spreading, but prevention is better than cure.
Disease forecasting with www.greencast.co.uk is an integral part of selecting the optimum timing for preventative fungicide application. Where weather conditions may have prevented application and disease symptoms are visible on the leaf, then products such as Banner MAXX or Daconil Weather Stick, will give stronger eradicant activity on turf diseases.
Rotation, Rotation, Rotation
An effective ITM fungicide plan must also include provision for fungicide rotation, using products with different modes of action to minimise the risk of disease developing resistance to any one group of fungicides. If a pathogen population begins to build up resistance to a dicaboximide fungicide, for example, switching to a demethylation inhibitor (DMI) would still offer complete control. The STRI (www.stri.co.uk) provides a valuable list of product groups and activity to minimise risk of resistance developing.
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Top Tips on Managing Resistance
- Avoid repetitive and sole use of a particular fungicide, or those with the same mode of action
- Always try to mix or alternate appropriate fungicides with different modes of action
- Do not reduce rates of strobilurin fungicides in tank mixes
- Integrate fungicide use with cultural control methods
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By rotating fungicides with different modes of action within the ITM plan, turf managers can effectively maintain the performance of fungicides in the long term.
How do you make an ITM plan?
There is no set example of how an ITM plan should look or how it should be set out, it really depends on how much time is available for making and working with the plan. Generally ITM plans build and develop over time, as further experience is gained and new options evaluated. The following points form the basic structure of an ITM plan:
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Site assessment – Identifying what pests and disease are likely to pose a threat and where the risk is highest. Create a map of high risk situations.
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Set thresholds – Decide what level of pest or disease damage is acceptable to managers and players, and when action will be required.
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Identify management options – Look at all available options, including cultural, biological, genetic and chemical. How should each one be used and to what degree?
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Build pest profiles – Record outbreaks on your turf area: type of disease; conditions that favour it; treatments to control etc. Accurate identification of pests and disease is essential to put in place the right plans.
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Create a pro-active turf management plan – How you are actually going to treat the problem. Record work carried out to control the pests and disease.
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Evaluation – monitor the results and continue to update the plan: did the treatments work?; can anything else be done to improve conditions in future?
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ABOUT THE AUTHOR Simon Elsworthis Head of Syngenta Professional Products for the UK and Ireland, including development of the specialist turf business and the web-based decision support system for turf managers, www.greencast.co.uk This article was first published in Greenkeeper magazine, as part of the Toro Continue to Learn series.