Can I Apply a PGR to My Greens?

We are receiving calls from southern Ohio asking if it is OK to apply a PGR to slow Poa annua

growth. Before answering that question, we thought it might be of interest to share some "January temperature" facts with you. As of January 25th, the average temperature is 40.4 F roughly 12 degrees above normal. January is on pace to be the second warmest on record. In addition, it is the warmest January in the last 10 years. It is also warmer than any December or February in the last 10 years. As a comparison, the average March 2005 (last year) temperature was 37.4 F.

Regarding applying a PGR to slow Poa annua growth on creeping bentrass/Poa greens the answer is yes. Trinexapac-ethyl (Primo®)would be the PGR of choice.

Although paclobutrazol (Trimmit®) could also be applied, we are hesitant to recommend this for two reasons. First, there is a potential for injury if frost occurs soon after appilcation. The second reason is that a restricted number of paclobutrazol can be made during a growing season. An application at this time would, we think, be a wasted application.

A follow-up question to applying Primo® that has been asked is, "If one or two applications are made now, and then the weather turns cold, will having the turf go in and out of regulation be detrimental?" The answer is no. Research has shown no detrimental responses from intermittent applications of Primo® at this time of the year.

Authors: David Gardner & Karl Danneberger