Which of the following is a root-infecting turf disease?

• A. Summer patch
• B. Fairy ring
• C. Necrotic ring spot
• D. Take-all patch

Answer: (C)

Root-infecting turf diseases attack the plant where it takes up water and nutrients—through the roots and crown—so the grass collapses under stress and patches form as the plant can no longer support healthy growth. Necrotic ring spot fits this heavily because its fungus invades the roots and crowns of cool-season grasses, causing necrosis and reduced root function. That root invasion leads to patches that may show circular or ring-like dead tissue within otherwise stressed turf, and the roots themselves often show decay or weakness, which aligns with a root-focused disease.

In contrast, fairy ring stems from soil fungi producing a visible ring of lush growth around a ring of dead turf, driven by nutrient and moisture effects on the grass rather than direct, consistent root invasion. Summer patch tends to present as drought-like symptoms and patchy dieback related to leaf and crown health rather than the root system itself. Take-all patch is also a root-infecting disease, but the hallmark rings and necrosis associated with necrotic ring spot make it the most characteristic example of a root-targeting turf disease in this set. Managing it involves improving drainage and soil conditions, avoiding prolonged drought and compaction, and applying appropriate fungicide treatments when necessary.