Late summer and autumn is the well-known time for applying Spring dead spot fungicides to prevent infestation of SDS the following Spring. Building a strong defense against SDS is now easier with the launch of VELISTA turf Fungicide from Syngenta.

The disease does not become active until temperatures are around 15 Degrees C in the winter time.  The issue with this is, that the couchgrass cannot compete with the fungal growth as the turf is dormant, and as we know the results can be catastrophic in the spring when the couchgrass breaks dormancy and attempts to reestablish itself as temperatures rise in the spring.

In order to maintain the couchgrass growth for as long as possible and to bring the couchgrass back after dormancy as quick as possible it is recommended that the surface be fertilized late in the season to maintain growth and to allow for carbohydrates to be stored in the plant over winter.  This storage then allows the turf to break dormancy when temperatures return to optimum, generally in the late spring. When adequate nutrition is applied in the late summer/ Autumn combined with an effective fungicide program, the levels of control is increased.

A successful preventative program is designed around providing as much active ingredient as possible into the plant. Hence a traditional program can often include up to 4 applications. A typical low-pressure program will include 3 applications (Table 1).

VELISTA contains a powerful new mode of action that is well suited for the prevention of SDS. VELISTA when washed into the root zone will move into the roots and lock into the root system offering long term protection. Importantly VELISTA does not have any growth retardant effects so will not slow down growth late in the summer season.

For SDS VELISTA offers several benefits over older technologies:

  • NEW mode of action Group 7 SDHI, offering excellent control
  • No phytoxicity to the plant. Suitable for late summer applications
  • VELISTA is locked in the root zone, it won’t translocate through the plant
  • Suggested low pressure SDS program
  • Easy to use available in 500Gram bottles

 

Table 1

Spring Dead Spot Control Options

March April May Application rate Irrigation  
BANNER MAXX X   10L/ha YES  
VELISTA   X 1.5Kg/ha YES  
  X 1.5Kg/ha YES  
VELISTA            

 

Symptoms

  • Circular patches of bleached, straw coloured dead grass appear in spring as the dormant grass regrows.
  • Patches are also visible in autumn and winter after a series of unusually cool days or wet, cold weather.
  • Patches are a few cm to 1 m in diameter.
  • Patches reappear and expand in the same spot for 3 or more years.
  • After 2 to 3 years, the centres of active patches may remain alive, and the patch takes on a “ring-like” appearance.
  • Roots of affected plants turn dark brown to black and are severely rotted.
  • Regrowth of grass into affected patches is slow and patches may remain barren or fill with weeds.

Conditions Favouring Disease

  • Most active when temperatures are cool (12°C to 14°C) and soil is moist.
  • Roots of Couch grow most rapidly at 24°C to 29°C and extremely slowly at 15°C, thus the fungus has a competitive advantage at low temperatures.
  • Spring Dead Spot favours cool, wet weather in the spring and autumn and daily temperatures of less than 15°C.
  • This disease is typically found where thatch is more than 1.2 cm thick and in locations with poor drainage and low potassium levels.
  • Heavy applications of nitrogen in late summer often increase disease severity the following spring.
  • Spring Dead Spot is more severe on turf that is over three-years old and in locations with long dormancy and cold temperatures.

Management Tips

  • Preventative fungicide applications during late summer and autumn.
  • Good fertiliser management especially nitrogen and potassium.
  • Control weeds in affected turf to enhance recovery from Spring Dead Spot.
  • Apply moderate to high levels of phosphorous, potash and minor elements.
  • Improve drainage of turf and reduce thatch.