SPRING DEAD SPOT

Causal Agent

Leptosphaeria korrae      

Susceptible Turfgrass

Common couch grass, South African couch grass and their hybrids 

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 centimetres 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 of 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 than15 C.
• This disease is typically found where thatch is more than 1.2 centimetres 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. 

General Comments

• Spring Dead Spot is typically a disease of mature turfs that are intensively managed.

Distribution

All states of Australia

 

Management practices 

• Preventative systemic fungicide applications during late summer and autumn.
• Good fertiliser management expecially 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.

Fungicidal control

The following products have label recommendation for Spring Dead Spot control in Australia:  

Parameter	Banner MAXX	Heritage
Mode of action	Systemic	Systemic
Optimum timing	When conditions favour disease development	When conditions favour disease development
Dose rate	10 l/ha	6 l/ha
Ideal water volume	600-1000 l/ha, wash in after application	600-1000 l/ha, wash in after application

Suggested Programme

 

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