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Rust

The majority of turf diseases are caused by fungal pathogens but some fungi are more strongly pathogenic than others. Many of the common cool season turf diseases are caused by fungi that rely on a weakened plant and therefore reducing disease incidence and severity is often aligned to maintaining a strong sward. With on-going changes to European Legislation relating to pesticide use, it is more important than ever that an integrated approach to disease management is employed and central to this is an understanding that the cultural conditions can limit disease development. Making use of the genetic variation that exists between grass types and cultivars can also minimise disease development through a sward. By managing rootzone quality and using weather information services, it can also be possible to pre-empt disease outbreaks and plan an efficient integrated management strategy.

Pathogen:    Puccinia & Uromyces spp.

Susceptible Species: Can affect all turfgrasses, but commonly seen on Perennial Ryegrass (Lolium perenne), Smooth-Stalked Meadow Grass (Poa pratensis) and Yorkshire Fog (Holcus lanatus).

Rust can develop on turf surfaces through the summer and can be a concern when large outbreaks occur in late summer.  The disease-causing fungi associated with rusts are obligate parasites which are species that require the plant cells to be alive for infection, therefore damage to the plant is rarely severe when rust alone is the issue.

Often seen in late summer/early autumn when conditions are right for disease development: – dew forming on the leaves for 10+ hours and temperatures of 10 -15oC.

Cultural & Chemical Prevention:

Fungicide applications are rarely warranted for Rust so cultural methods are preferred.  Control and improvement can usually be achieved by correcting any soil moisture deficiencies and applying nitrogen.

Where irrigation is not available, consider an application of a wetting agent prior to any rainfall event to maximise the plant usage of the water if drought is the problem.

If compaction is leading to reduced growth look at spiking, vertidraining or air injection treatments to relieve plant stress.  Shade can also contribute to poor growth and rust development, so selected tree, shrub and limb removal should be employed to maximise light availability whilst also improving air movement and reducing leaf wetness.  This work should be adopted for all sports turf surfaces as high levels of light and airflow are vital for producing a good quality surface.

Different cultivars within the same species can often have very different levels of rust susceptibility, so overseeding with different cultivars will give you the best chance of avoiding damage across the whole surface.

If the turf affected is not thinning or causing an issue with playability, then it is often the best solution to simply let the disease run its course.  Where budgets are limited this is often the only option.

Example of Rust

Symptoms

Initial symptoms are a slight discolouration of leaves which develop into the familiar orange/rust coloured pustules on the leaf surface.  These will produce spores which can often be seen as orange dust covering footwear and machinery when walking/operating on the infected turf surface.

Rust generally only infects slower growing turf that is mown above 10mm.  A sward stressed by drought is also more liable to infections.

Non-Pesticial Rust prevention

  • Maintain adequate soil moisture
  • Ensure sufficient nitrogen is available
  • Identify irrigation issues and remedy
  • Apply a wetting agent to reduce drought stress
  • Maintain shrubs and trees to reduce shade and increase airflow
  • Collect clippings to reduce spread of disease spores

Rust is not a severe disease and many sites can simply wait until conditions change and the disease disappears.  If rust is an ongoing problem year after year, then look at the under lying causes and be prepared to invest in solutions such as irrigation systems or fertiliser programmes.