While conducting a recent Course Consulting Service visit in the Midwest, I was looking at summer patch damage and noticed that some areas of turf were unaffected. Upon further evaluation, I saw that the unaffected turf was perennial ryegrass, which isn’t susceptible to summer patch.
Summer patch (Magnaporthiopsis poae) is a fungal disease that begins to develop once soil temperatures reach 65 degrees F in the spring, but damage isn’t often seen in the Midwest until late July and early August when infected roots are stressed from summer conditions. It impacts Kentucky bluegrass, annual bluegrass, fine fescues and creeping bentgrass. It doesn’t impact perennial ryegrass or tall fescue, both of which are commonly found in cool-season roughs.
Areas that experience summer patch often see infection on an annual basis with the infection slowly spreading from year to year. Interseeding species that are not impacted by summer patch is a good idea for rough areas that are not intensively managed and do not receive preventive fungicide treatment.
If you are interseeding or renovating roughs at your course, there are advantages to incorporating genetic diversity in your seed mix. Seed mixes that contain approximately 85% tall fescue and 15% Kentucky bluegrass by weight (a 1:1 seed count ratio) work well for golf course roughs as that yields a stand that is approximately 50% cover of each species. The tall fescue can mask the effects of summer patch in Kentucky bluegrass, and the Kentucky bluegrass can mask the effects of brown patch in tall fescue.
For additional information regarding turf selection at your course, reach out to your local USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org
Information on the USGA’s Course Consulting Service
Contact the Green Section Staff