Pest Alert №8 — Summer Patch
Golf greens with a high proportion of annual bluegrass or Poa annua are susceptible to a fungal root disease known as summer patch (Magnaporthe poae). This is the same disease that can be problematic in Kentucky bluegrass lawns each summer. There’s a famous photo (if you are a turf disease fan) in at least one turfgrass disease textbook of President Johnson speaking outdoors with the White House lawn front and center. You can’t help but notice that in the foreground the Kentucky bluegrass is totally decimated by large, brown, dead patches/summer patch. It tells a story. Would’ve been a wet summer in Washington DC. And the cameraman didn’t use a green filter.
This year Chicago’s especially dry conditions that began in spring were interrupted by a series of rain events that began during the second half of June. Saturated soils about midsummer resulted. This was all that was needed to trigger root rots. Once started, the effects can be long lasting.
Fungicides. Many fungicides are labeled for control of summer patch. Just remember to read the label AND water-in immediately after application. If you don’t water-in it may never reach the roots. How deep do I position the fungicide? To the depth of your green’s roots. This is a dynamic system and about midsummer roots are at their shortest for C3 (cool-season turfgrasses). But you will need to check it out.
Cultural Practices. Do anything that can reduce turfgrass stress. That brings to mind a few things: Raise the mowing height, reduce equipment compaction if possible, use all portions of the green for pin placements, monitor and rotate the on/off traffic to greens, practice midday wilt stress mitigation via hand watering (especially on weekends… I dare say).
