Which disease is a cool-weather disease of Kentucky bluegrass and creeping bentgrass, with infected blades pale green and long black streaks?

• A. Stripe smut
• B. Fairy rings
• C. Microdochium
• D. Leafspot and melting out

Answer: (A)

The feature being tested is matching symptoms to a specific cool-season turf disease.

Stripe smut fits because it targets cool-season grasses like Kentucky bluegrass and creeping bentgrass and produces the characteristic look described: blades that stay pale green while the infection travels as long, dark black streaks along the leaf. The streaks are spore-filled smut that stains the blade black as the disease progresses, which is a hallmark of stripe smut under cool, wet conditions.

Other diseases don’t match this pattern. Fairy rings create circular rings of lush turf with mushroom fruiting bodies, not pale blades with longitudinal black streaks. Microdochium (snow mold) patches and melting-out symptoms look different and are tied more to prolonged cold or wet stress, not the distinct streaking along leaf blades. Leafspot and melting out typically produce spots and patches under different environmental conditions and do not present the long black streaks along blades seen with stripe smut.

So, the described symptoms are most consistent with stripe smut.