Clarireedia spp.

Dollar Spot

Other common names:

Springy.

 

Description:

Dollar spot is a foliar disease. It occurs as small, circular spots or lesions that can enlarge and coalesce to form large circular or irregular areas of dead turf. The dead leaf tissue is usually straw-coloured. The disease is favoured by low nitrogen levels in the soil and long periods of leaf wetness. Fine, white, webbed mycelium can be observed across the leaves in the presence of high canopy moisture (rainfall, irrigation or dew). Fungal growth occurs above 16°C is optimum between 21-27°C. The disease is normally found on established turf and has low economic significance. Dollar Spot has a worldwide distribution, and also affects cool-season turfgrasses. Content from Loch and Bransgrove (no date).

 

Molecular analysis by Rutgers, Ohio State and NC State Universities has shown that dollar spot pathogen is not a true Sclerotinia and that it is unlike any other fungal genus. They note that there are 4 distinct groups of fungi that cause dollar spot worldwide and the new proposed 4 species names (as of 7 Feb 2018) are:

  • Clarireedia jacksonii - cool-season turfgrasses;
  • Clarireedia monteathiana - warm-season turfgrasses;
  • Clarireedia homoeocarpa - original UK isolate; and
  • Clarireedia bennetti - additional isolates from R. Fescue (UK).

 

Control options:

  • Pesticides:
    • See available tabs below for registered products. Use as per label instructions.
    • If the disease is common to your turf (known history), apply a preventative fungicide application during late summer and autumn.
    • Chemical control measures (currently registered in Australia) include products with the following active ingredients: bitertanol, carbendazim, chlorothalonil, prochloraz, procymidone, propiconazole, thiram, thiram+quintozene, thiram+metiram, thiabendazole and triadimenol.
  • Integrated Pest Management (IPM):
    • Use a combination of approaches listed on this page.
  • Cultural:
    • A disease outbreak such as dollar spot might have been triggered by late afternoon/early evening watering of the lawn. The excess moisture applied by our sprinkler may not seem a problem but at night this moisture takes far longer to dry off the leaf surface and can result in favourable conditions for disease development. 
    • Reduce thatch levels within the turf sward. Maintain turf density and nutrition, especially nitrogen and potassium, to at least an acceptable standard.
    • Control weeds in affected patches to limit competition and enhance recovery.
  • Mechanical:
    • Improve drainage and airflow within the soil profile. Routine decompaction work will assist here.

 

Disclaimer:

Turf Finder or its developer accepts with no responsibility for any consequences whatsoever resulting from the use of any information or product(s) listed herein. Products are to be applied as per label instructions.

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