Patch Disease

Summer Patch and Necrotic Ring Spot in Kentucky Bluegrass Lawns

Summer patch disease and necrotic ring spot are significant root-infecting diseases affecting Kentucky bluegrass. These diseases, differing slightly in their development phases, typically activate pathogens from late spring to early summer. They impair the roots’ water absorption and transfer capabilities, leading to distinct symptoms under drought stress. Affected turf commonly exhibits yellow-tan arcs, rings, or “frogeyes.”

Identifying Summer Patch and Necrotic Ring Spot Symptoms

The severity of symptoms increases in lawns with more than 0.75 inches of thatch. In these lawns, roots tend to grow in the thatch, which doesn’t retain much water, leading to quicker symptom manifestation. Sodded lawns with poor initial preparation (such as insufficient tillage) are particularly susceptible. In these cases, roots fail to penetrate deeply, making the lawn vulnerable to drought stress. Wet spring conditions exacerbate the problem by promoting shallow rooting in waterlogged soils. These symptoms usually appear two to three years post-sodding, while seeded lawns may take even longer to show signs.

Effective Management of Summer Patch and Necrotic Ring Spot

Professional intervention is recommended for chemical control of these diseases. For lawns that frequently suffer from these diseases, overseeding with perennial ryegrass can be an effective strategy to mask symptoms. This solution works well as long as the lawn can also manage other potential diseases like dollar spot, red thread, and brown patch.

Preventative Strategies for Kentucky Bluegrass Health

In addition to these measures, maintaining a healthy lawn through proper mowing, watering, and fertilization can help prevent the onset of summer patch and necrotic ring spot. Regular aeration to reduce thatch buildup and improve soil structure also plays a crucial role in disease prevention. By creating a robust and resilient turf environment, the impact of these diseases can be significantly minimized.