With the British climate offering an ideal habitat for disease pathogens to thrive, Greenkeepers face a year round battle against fungal turf disease. This year has been exceptionally challenging, with pockets of heat followed by extremely heavy and, at times, prolonged rainfall, not to mention the severe flooding in some regions. Bayer's Field Sales Support Manager, Dorin Pop explains why gaining a clear understanding of disease development is vital when trying to gain control this autumn.
"The first step in disease management is to identify the true nature of the problem," says Dorin. "When a variety of environmental factors come together, the likelihood of an outbreak is greatly increased." Fungal turf disease is almost certain to develop when susceptible grass species interact with a disease producing organism and an environment favourable to disease development.
Environmental factors such as temperature, the intensity of light and moisture are key elements to consider from the outset. "Areas of the green that are cast in shadow caused by the angle of a slope or nearby trees and buildings will be damp either after rainfall or from morning dew, and will remain so for a considerable time," notes Dorin. "These wet conditions provide a habitat more conducive to disease. Other factors include air and water drainage, with aerated soil both drying and draining more efficiently."
As we head further into autumn, there is the added risk of an outbreak of Microdochium nivale. This strain of the disease will be triggered by lower temperatures and wet weather. In the event of a snowfall later on this winter there will be an added risk of pink Microdochium nivale or grey snow mould (Typhula incarnata) which commonly develops during prolonged periods of snow cover, with symptoms of the disease becoming evident as thaw sets in."
When trying to protect turf, the environment can be altered in many ways, depending on the disease. For example, effective cultural approaches include dew removal and a reduction in the amount and/or frequency of irrigation. Air and water movement within the sward, fertiliser levels and appropriate mowing practices are further factors affecting overall sward health. "Successful control of turf disease relies on incorporating these practices alongside a turf fungicide programme," notes Dorin. "We refer to this as an integrated disease management programme."
While a preventative approach could be considered, it's important greenkeepers recognise symptoms when they do have disease. Symptoms can often be seen as visible patterns on the turf and can appear as spots, patches, rings, circles. Symptoms to look for on individual plants include leaf spots, wilt, yellowing, stunting, and root rot. Dorin states that leaf spots can be very good diagnostic 'signs'. "The leaf spots of different diseases are usually unique in shape, colour, and size."
For most greenkeepers the most practical way of identifying and controlling turf disease is to frequently monitor greens for the first signs of infection and relate that to the past and future weather conditions. It is important to identify any disease early before it has had the chance to develop and scar the turf especially as we go into the winter.
The final aspect of disease management is the application of a fungicide. Dorin explains that this approach forms the backbone of Bayer's Turf Fungicide Programme which utilises both Chipco Green® and Dedicate®. "Chipco Green® has preventative, curative and early eradicant properties; its dew switching properties complements the other cultural activities by reducing the need for switching on turf up to two weeks after application," states Dorin.
He adds that Dedicate® is Bayer's newest fungicide and forms the other half of the fungicide programme. It has both a contact and systemic mode of action which offers long-term preventative and early curative control of turf disease.
Both products are rainfast within an hour of application and are therefore well suited to the unpredictable weather.
"A programme of this nature is designed to offer the most effective solution to turf fungicide problems, and is recommended to all greenkeepers who want to quickly and effectively gain control of a sudden disease outbreak," concludes Dorin.