Fusarium Patch Disease

It is acknowledged that Fusarium patch also known as Microdochium patch is the most common and damaging turfgrass disease of parkland golf greens. It was first recorded on golf greens in 1931 and was described as being the commonest, most disfiguring and damaging disease of turf known at that time. Ninety years later and this statement still holds true.

Reducing the number of Fusarium patch disease outbreaks and the severity of any disease is aligned with creating conditions for a healthy sward. Pathogenic fungi that attack the grass plant are usually present, however it is only when the environmental conditions are favourable to them that they cause disease of turf. These soil fungi rely on a weakened grass plant to be able to take hold and cause visible damage to turf quality and playing surface performance.

Recognition

Fusarium patch is favoured by cool, wet weather and was typically a disease of autumn and early winter months. With changing, wetter, weather patterns over the past 12-18 months this disease can occur at any time of year. It usually first appears as small, up to 50mm diameter, orange/brown, water-soaked circular spots which, under favourable conditions, may increase rapidly and coalesce together to form larger circular patches of damage. Correct diagnosis of these early signs is important as the best possible control will be achieved if the disease is treated at an early stage.

Care should be taken in identification as chemical or fertiliser scorch may appear surprisingly similar. An incorrect disease diagnosis may lead to wasteful and expensive applications of fungicide.

Under prolonged humid conditions, sparse white or pink mycelium may be seen around the edges of each patch which tends to mat the green leaves together. A pale straw colour at this time indicates that the disease has become less active, perhaps due to a drier climate. Eventually scars are formed which, particularly in the winter months, heal slowly and are consequently prone to invasion by moss, undesirable grass species and weeds.

Conditions that Favour the Disease

The disease is typically damaging on close-mown, intensively managed turf such as golf or bowling greens where the sward contains annual meadow-grass (Poa annua), as this grass is highly susceptible to damage.

High fertility conditions often created by fertiliser applications can promote outbreaks of this disease.

Fusarium patch is favoured by the presence of thatch, due to moisture retention and the dead plant material providing a natural substrate for the disease.

Turf that is shaded from the sun or in a sheltered location, e.g. due to the close proximity of tall trees or buildings, will be more susceptible to disease.

Note the disease is most active in alkaline turf, potentially triggered by the use of top dressing sands with a high lime content.

Recommendations for Control

The ready availability of fungicides in past years made control of this disease relatively straightforward, especially if disease activity was spotted and treated early.

However as access to effective fungicide products is and will become increasingly difficult the emphasis has to be on year round cultural techniques to improve grass plant health, manage thatch, improve rates of moisture infiltration and maintain appropriate fertiliser and sand top dressing inputs.

Management practices that helps to keep the turf surface dry, such as switching, aeration or appropriate soil surfactant applications will also reduce the likelihood of fusarium patch activity. In addition promote improved air circulation and shade reduction by tree removal wherever possible.

The better the environment for growing strong healthy turf the less potential there will be for Fusarium patch disease activity at any time of year.