The causal agent for red thread or pink patch is Laetisaria fuciformis and Limonomyces spp. It is generally noticed as brown patches appearing in the lawn. Closer inspection particularly at the outer edges of these brown areas will reveal the characteristic red threads of mycelium growth. This is the most common disease exhibited on lawns comprised particularly of ryegrass or fine fescue, however, it can affect all other turf species. It is primarily a function of nitrogen deficiency and can occur at any time of the year, but tends to be more common from autumn until spring when consistently moist leaf blades provide ideal conditions for its propagation. It can be very site specific particularly in areas that are well sheltered or shady. Red thread can be prevalent on new sites particularly when the topsoil has been removed and replaced. The base saturation fertility level on these soils is low and as a result the plants struggle to uptake sufficient nitrogen to meet their requirements. It can take some time to build this fertility back to desirable levels. Therefore, during this period of time a regular balanced fertilizer regime is recommended.
- Apply a nitrogen fertilizer such as Turf Supreme at 40gms/m2 or 4.0kgs per 100m2. Follow up with an application of Turf Gold in 3 weeks time at a rate of 35gms/m2 or 3.5kgs per 100m2. Thereafter continue applications every 8 -10 weeks until the problem abates. As the soil fertility increases the likelihood of a red thread outbreak will decrease, however, this may take some time to occur particularly on sandy soils or soils containing low levels of organic matter. Ensure that mower blades are sharp to provide a clean cut to the leaf blades, because leaf exudates formed at mowing wounds form favourable media for spore germination and mycelial growth. Restrict foot traffic on the lawn until symptoms desist. If irrigating or watering the lawn ensure that this occurs in the morning rather than the evenings. If conditions persist then a fungicide such as Taratek or Chlorotek should be applied at label rates. This should generally take place as two applications 14 days apart. Thereafter continue with the regular nitrogenous fertilizer applications.
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