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Spring Dead Spot (SDS)

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Shanie McElreath avatar
Written by Shanie McElreath
Updated over 3 months ago

Causal Agent:

  • Ophiosphaerella korrae

  • Ophiosphaerella herpotricha

  • Ophiosphaerella narmari


Susceptible Turfgrasses:

  • Bermudagrass

  • Zoysiagrass

  • Buffalograss


Identification:

Spring Dead Spot (SDS) appears as turfgrass emerges from winter dormancy, presenting the following symptoms:

  • Patch Appearance:

    • Bleached, straw-colored circular patches ranging from 6 inches (15 cm) to several feet (up to 1.5 meters) in diameter.

  • Root Damage:

    • Affected plants display shortened, dark-brown to black roots, impairing recovery.

  • Frog-Eye Symptom:

    • Patches may feature living grass at the center, creating a "frog-eye" appearance.

  • Distribution:

    • Patches can occur in isolation or affect widespread areas of turf.


Favorable Conditions:

The following conditions promote Spring Dead Spot development:

  • Seasonality:

    • SDS pathogens thrive during cool, wet fall weather when soil temperatures drop below 70°F (21°C), followed by a cold winter.

  • Winter Impact:

    • Disease severity increases after mild winters, especially in areas with extended periods of winter dormancy.

  • Soil and Thatch:

    • More common in areas with thatch > 0.5 inches (1.3 cm) thick and in exposed, poorly drained locations.

  • Fertilization:

    • Heavy nitrogen applications in late summer or fall contribute to disease progression.

  • Cultivar Susceptibility:

    • Older bermudagrass cultivars and highly susceptible varieties are at greater risk.


Management Tips:

  • Thatch Management:

    • Dethatch regularly to reduce organic material where SDS pathogens thrive.

  • Proper Fertilization:

    • Avoid excessive nitrogen applications in late summer or fall to prevent disease escalation.

  • Soil Health:

    • Improve soil drainage and aeration to reduce environmental stressors.

  • Cold-Weather Preparation:

    • Strengthen turf before dormancy with balanced potassium applications to improve winter hardiness.

  • Resistant Varieties:

    • Consider planting SDS-resistant cultivars in areas with a history of the disease.

  • Potassium

    • Should also be applied in the fall where the disease is chronic to boost winter hardiness.

  • Apply Ammonium Sulfate

    • Or other acidifying nitrogen sources combined with potassium at spring green-up and thereafter until full recovery has been achieved.

  • Apply Preventive Fungicides

    • In the fall when soil temperatures are below 70°F. Two applications on a 28-day interval are recommended in most cases.


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