Copper Spot --- Can be confusing at first glance!

First reported case of copper spot (Gloeocercospora sorghi) occurred this week from a central Ohio golf course green. The turf affected was creeping bentgrass. This is one of the few confirmed cases of copper spot that we can remember. Historically, copper spot is not a widespread problem in Ohio.

Symptoms: At a glance the overall symptoms appeared similar to anthracnose. The color of the turf is rust to reddish-orange color (remember a pathologist description of colors may not be what you may picture in your mind so look at the photos) and affected turf is in spots that are 1-3 inches in diameter and can run together to cause decline of large area(s). Leaves may have small spots / lesions that are reddish or brown and entire leaves rapidly die. Under the microscope there are abundant long multiseptate conidia which make identification rather easy.

Environment: Occurs in warm 70's to 85 F, wet weather, with long periods of wet leaf tissue. Not a wide spread disease and often occurs with dollar spot (see photos). High rates of fertilizer increase the disease.

Management: Avoid excessive fertilization. Maximize the time foliage is dry. Recommended fungicide information is some what limited but - chlorothalonil, iprodione, thiophanate methyl, myclobutanil, and triadimefon have been reported as materials to use.

Authors: Joseph Rimelspach & Nancy Taylor