This week's weather prediction for more rain and cooler temperatures increases the potential for melting-out/leaf spot on Kentucky bluegrass. Last week's rain saturated the soil profiles and has set the stage for this disease to become more widespread. Melting-out attacks Kentucky bluegrass roughs and fairways during cool wet weather. This disease can cause thinning of the turf. Control measures depend on the situation. In many instances the disease is considered a minor disease and is allowed to run its course. Nitrogen applications are usually not recommend unless the turf is "starving". In this case nitrogen can reduce the severity. If the disease is severe enough to warrant of fungicide applications, several products are available.
Melting-out/leaf spot can occur on creeping bentgrass. I have noticed however where mefluidide (Embark®) applications have been made for Poa annua seedheads that the creeping bentgrass can turn off-color (bluish), which may be confused with melting-out.
For more information on melting-out and its control:
Mean daily soil temperatures (F) at the 2" depth on May 20, 2001 for: Kingsville - 63.8, Wooster - 64.9, Hoytville - 65.3, South Charleston - 67.3, Oxford - 74.5, and Jackson - 71.0 Authors: DrD
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