Empty Core Holes?

Question: Dr. Shetlar I have been on a couple of golf courses the last week that have cored and filled the holes with sand. I have noticed that a few to many of the holes are not "filled"(photo to the left). I assumed that birds have pecked in the holes and "kicked-out" the sand. If this is true, what are the birds pecking for?

Dr. Shetlar:It has been my experience that birds will peck at almost any imperfection to the surface of greens and tees. I'm a bit surprised that this would be happening this early, as new fledgling starlings haven't arrived yet. Fledglings take awhile to develop a good search image and they will even peck at dollar spot symptoms!

At this time, in Ohio, the overwintered sod webworm larvae should have come to the surface and resumed feeding. These sod webworms usually make a small crescent-shaped brown mark, just below the mow line (photo 2). This mark is actually webbing with top dressing and grass clippings. Birds commonly figure out what these are and that there can be a tasty tid-bit just below the webbing. If a superintendent has these and the coring holes, the birds may be picking at the core holes, filled with topdressing, thinking that they may be a sod webworm mark.

Authors: Dave Shetlar & Karl Danneberger