Integrated route to tackle threats of turf diseases

Turf managers across the UK had the opportunity to learn the very latest techniques in Integrated Turf Management (ITM) at a series of seminars organised by Syngenta and Scotts.

UK turf managers could learn valuable lessons from colleagues in the US to tackle the increasing problems of turf diseases, Anthracnose and Dollar Spot. Syngenta US Turfgrass Technical Manager, Mike Agnew, warns experience in Philadelphia, where conditions are very similar to the UK, indicates Anthracnose will become a year-round problem.

Speaking to green keepers and turf professionals at a series of meetings organised by Scotts and Syngenta across the UK last week (19 - 23 March), Dr Agnew highlighted that Anthracnose can be the most devastating disease encountered, and that it had increased in incidence from a summer problem, to now affect turf from February to November.

Some strains of the disease only affect the leaf and cause little damage, unless the turf is physically damaged when disease can get in; control with Daconil Turf is easy and highly effective, he advised. However, Dr Agnew advocates turf managers carry a pocket microscope to closely inspect suspected Anthracnose infections: "If you see the disease fruiting bodies, however, there's a real chance that it will attack the base, stem and crown and cause basal rot and requires urgent action; if you are seeing black stems the plant's vascular system has already gone and it may be too late."

Low cutting height, low N fertility and environmental stress all favour the development of Anthracnose, according to Dr Agnew. "If you can raise the cutting height by 0.5 mm it can make a real difference, even if that means rolling more frequently. Alternatively, the use of Primo MAXX to create a denser sward can allow cutting height to be raised, whilst maintaining or improving the speed of play."

Growth regulation

But Dr Agnew warned that not all plant growth regulators (PGRs) will help the situation. "PGRs that simply stop growth, such as maleic hydrazide, means turf can not recover from disease infection and can exacerbate the effects. With gibberellic inhibitors, such as Primo MAXX, vertical growth is slowed and energy diverted into lateral and root growth - to create a stronger, healthier sward base that is better able to resist disease attack, and able to recover faster."

He also reported trials have shown that by maintaining appropriate nitrogen levels it is possible to reduce the incidence of Anthracnose. "You won't eliminate it by fertility alone, but it can significantly reduce the level of infection and allow fungicides to work more effectively in controlling the disease," advised Dr Agnew.

New Integrated Plans

Nick Martin of Scotts reported nitrogen input has been falling over recent years, resulting in increased stress on turf and an increased incidence of disease. "Nutritional solutions could help other control measures work more effectively in future Integrated Turf Management (ITM) programmes to counter newly emerging disease problems," he said.

"Just a few years ago Dollar Spot was only a minor problem for isolated courses in the far south west. Now it has been reported from Cornwall to Scotland, and the incidences are becoming worse and more difficult to control," he added. He highlighted that Scotts and Syngenta will be developing new ITM plans for turf managers that will pull together all the facets of cultural management, nutrition and chemical control techniques, and can be tailored to specific conditions on individual courses and holes.

As turf is managed ever more intensively the incidence and intensity of turf disease is increasing with the Sport Turf Research Institute (STRI) and The Turf Disease Centre reporting an increasing number of samples submitted for testing every year, according to Simon Barnaby, Syngenta UK Technical Manager for turf.

Predicting disease

He highlighted the new Syngenta fungicide, Banner MAXX, has given turf managers an extremely fast acting and entirely new active ingredient for broad-spectrum disease control, including Fusarium (Microdochium Patch), Dollar Spot, Anthracnose and Brown Patch.

"For best results with Integrated Turf Management (ITM), turf managers need to implement appropriate cultural management practices and then be able to select the most appropriate product and to alternate the product chemistry to maintain good results and minimise risk of resistance. With the introduction of Banner MAXX - propiconazole - we now have three different fungicides with three different modes of action that gives turf managers the complete package for a three pronged attack on disease - all within the Syngenta range."

Allied to the web-based decision support system - www.greencast.co.uk - Mr Barnaby said fungicide applications can now be timed more effectively than ever before. "The latest evaluation of GreenCast by STRI has confirmed up to a 95% accuracy of disease prediction. It's now a valuable tool that can help make better decisions as to when and where to spray, with the proven potential to reduce overall fungicide applications by up to 25%, whist still delivering improved disease control."

Spray Nozzle Technology

Sprayer nozzle selection can make a significant difference in the efficacy of fungicides, according to extensive research in the US, according to Dr Mike Agnew. He reported that when many greenkeepers switched to nozzles with large orifices creating big drops to minimise the risk of spray drift, results in terns of disease control fell dramatically.

"Larger droplets may work OK for systemic herbicides or broadleaf weed control, but for disease control you need a medium to fine spray pattern," he advised. "Remember, that when droplet size is halved, the number of droplets increases eight-fold, which significantly improves leaf coverage."

Dr Agnew believes the XR flat fan nozzles commonly used by UK turf managers are essential for spraying greens and fine turf, to get spray penetration to the stem base. "Research has shown they can achieve very good results, but don't be tempted to go for too large a nozzle size to apply higher water volumes at faster speed, if it will compromise droplet size and spray quality," he warned.

A further new development in nozzle technology which has achieved very good results has been the introduction of air induction nozzles, added Dr Agnew. Air-induction nozzles are especially designed to incorporate a bubble of air into each droplet, which increases the drop size to minimise spray drift, yet burst when it hits the target to give good spread and leaf coverage. "They are an excellent technical solution to give green keepers more spraying opportunities, as well as improving the results achieved," he said.

Photo Cation:- R-L Nick Martin, Dr Agnew, Simon Barnaby and Simon Elsworth.

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