Fusarium patch disease, a prevalent turf affliction in the UK, is attributed to the fungus Microdochium nivale (previously known as Fusarium nivale). Recognized as one of the most detrimental lawn diseases in the region, its incidence has been on the rise due to milder, wetter winters which create an environment conducive to its spread. Moreover, the decreasing occurrence of hard frosts, which typically curtail the pathogens causing fusarium, is exacerbating the issue.
Identifying Fusarium Patch
Fusarium patch typically manifests as orange or brown circular spots with a diameter reaching up to 50mm or roughly 2 inches. Under conditions conducive to its growth, these spots can rapidly expand. They are particularly discernible during the early morning dew. Extended periods of humid weather can lead to the appearance of a pink mycelium ring encircling the infected turf area.
Conditions Promoting Fusarium Patch
Several factors can elevate the risk of a fusarium patch outbreak:
- Climatic Conditions: Mild and wet conditions are prime for the disease.
- Grass Type: Lawns with a high percentage of annual meadow grass are especially vulnerable as this type is highly susceptible to the disease.
- Fertility Levels: High fertility, especially if caused by excessive nitrogen application in late summer or early autumn, can encourage the disease.
- Thatch Layer: A deep thatch layer on the lawn can be problematic.
- Location: Areas sheltered from sunlight, particularly those with poor surface drainage or high surface pH, can foster the disease’s growth.
Managing Fusarium Patch
Prevention remains the best strategy against Fusarium patch, especially since fungicides – a common remedy – are not accessible to hobbyist gardeners. Nonetheless, several cultural practices can aid in preventing the disease:
- Nutrient Management: Refrain from applying substantial nitrogen amounts late in the season. An early autumn potash application can bolster the plant’s resistance against the disease.
- Dew Removal: Early morning dews can be cleared using a wide drag brush or a switch, a tool made from cane or fibreglass poles, swept across the lawn to eliminate the dew.
- Grass Type Transition: Since annual meadow grass is prone to fusarium patch, adopting proper maintenance practices can promote the growth of more disease-resistant grass varieties.
- Thatch Reduction: If the thatch layer is excessively deep, aeration and scarification can help in its reduction.
- Sulphate of Iron Application: This compound acidifies the lawn surface, deterring the disease. Lime application should be minimal and only when deemed absolutely essential.
- Improving Drainage: Enhance surface drainage with regular aeration and by adding a sand-based top dressing.
- Addressing Sheltered Areas: If feasible, prune or trim vegetation in areas sheltered from sunlight, as these can become hotspots for the disease.
In summary, while Fusarium patch disease poses a significant threat to UK lawns, understanding its causes and implementing proactive measures can help in managing its spread and impact.
