In droughty areas under heavy wear perennial ryegrass leaves have turned yellow (in other areas the perennial ryegrass looks great). The leaves often appear yellow from the tip back (tip die back). In many instances the perennial ryegrass has undergone drought stress causing the "leaf firing" often associated with moisture stress (Photographs 1 and 2). The lack of rainfall, low humidity, wind and relatively low moisture have enhanced the leaf symptoms. In addition, rust can cause yellowing of the turf and might occur on perennial ryegrass that is under moisture stress. Given the rain that fell across most of Ohio the last couple of days active growth should resume and improvement in the perennial ryegrass should be observed.
I have also observed leaf spot on perennial ryegrass. The disease appears to be of minor importance occurring in isolated patches. The patches appear reddish in color and have the typical leaf spot lesion.
Authors: Karl Danneberger
Copyright OSU Buckeye Turf Program. Website manager: Dr. Tim Rhodus