P&PDL Picture of the Week for
November 15, 2004

Taking Preventative Action

Glenn Hardebeck, Turfgrass Research Agronomist, Department of Agronomy , Purdue University

Summer patch is an infectious disease that can become a problem in sodded lawns for several years after sodding, especially where sod has been laid over compacted soil.  The visual symptoms show up during summer drought/heat stress due to a deteriorated root system infected by the disease.  Patches of droughty turf 6-12” in diameter can develop with green turf in the center forming a classic “frog eye” appearance.

One of the primary cultural practices to reduce the incidence of summer patch is to reduce the soil compaction through core aerification.  True aerification involves physically removing a core of soil not just pushing a hole into the ground with a spiker.  While aerification is best performed in the spring and fall during active growth, it is still beneficial to aerify a compacted lawn well into late fall.  Therefore, a lawn that has had summer patch or newly sodded lawn that has rooted down well enough so that it won’t roll up on the aerifier could be aerified yet this fall and again next spring.  Aerify aggressively by running the core aerifier 2-3 directions across the lawn.  The rain will break up the soil cores with time and the Kentucky bluegrass roots will breathe a sigh of relief.  The healthier root system will better fend off the effects of potential summer patch infections.  More information on summer patch can be found at http://www.ces.purdue.edu/extmedia/BP/BP-115-W.pdf

Click image to enlarge

Typical frog eye pattern due to summer patch during July and August.

Pull type core aerifier

Walk behind lawn core aerifier

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service