Jul 27

Summer Drought Stress – Watch Out for Anthracnose Foliar Blight

Although a change from the recent blisteringly hot, dry weather is certainly welcomed, changeable milder weather with some rainfall will undoubtedly see a spike in the turfgrass disease Anthracnose foliar blight (Colletotrichum graminicola).

Anthracnose typically attacks annual meadow grass plants when they are under stress. It is triggered by environmental stresses including heat and drought, low nutrition and compaction which lead to reduced plant health. Symptoms include a yellowing to reddish brown discoloration of leaves and a general thinning of the turf. Turf deterioration can be rapid under certain conditions. Available fungicides are not particularly effective and the best approach is typically to reduce all turf stresses and ensure balanced nutrition to help the sward recover from damage.

Pro Tips from Aquatrols Europe

Short Term Strategy

  • Reduce drought stress and ensure sufficient moisture content with the use wetting agent products as necessary to remoisten dry soils uniformly to depth.
  • Irrigate in the morning to minimise long periods of leaf wetness particularly overnight.
  • Use a penetrant wetting agent to move water through the upper soil profile and to keep the surface dry. An application of Dispatch Sprayable @ 1.75 L/Ha or equivalent will work well.
  • Relieve turf stress by raising the height of cut and reduce mowing frequency. Replacing mowing with rolling can be beneficial.
  • Avoid mechanical treatments such as verti-cutting and grooming as these cause further stress to the already weakened grass plants.
  • It is usually appropriate to make an application of fertiliser to aid turf recovery. Address this as appropriate with applications of Super Concentrate Super N @ 20L/Ha or equivalent.
  • Aerate to relieve compaction and to improve air exchange within the profile taking care to avoid further turf surface damage or stress.
  • Fortnightly tank-mix applications of TurfRx OxyCal @ 4.5kg/Ha and TurfRx NatureCur @ 10L/Ha can be used to promote turf recovery once disease activity has lessened.
  • Take advantage of any sward thinning by overseeding as soon as conditions suit growth.
  • Use fungicides as part of an Integrated Turf Management (ITM) programme, however fungicides may give only limited control of anthracnose foliar blight. Resistance management should always be practiced and include the rotation of fungicide chemistry.

Longer Term Strategy

  • Revisit the fertiliser programme to ensure under or over applications of nitrogen are avoided.
  • Improve the micro-climate by increasing light levels in shaded environments and by promoting better air movement.
  • Applications of the Tough Turf tank-mix can be beneficial through autumn and winter – 10L Ferrosol, 10L CalSea Xtra and 10L Premium K/Ha.
  • During periods of hot, dry weather minimise mechanical turf stresses to avoid increasing vulnerability to anthracnose foliar blight and other turfgrass diseases. 
  • Implement a programmed approach to water management with the use of proven Aquatrols wetting agent products to reduce potential for drought stress and maintain healthy, strong turf surfaces.
  • Fortnightly tank-mix applications of TurfRx K+ Micro Crystal @ 4.5kg/Ha and TurfRx Ca @ 5L/Ha will improve abiotic stress defences and cell wall strength while disease pressures are high.
  • Improve sward composition through overseeding to reduce the amount of annual meadow grass in the sward.  Sward composition gains can take time but persevere.

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