Timing Is Everything March 17, 2017 By Zachary Nicoludis, agronomist, Central Region

The emergence of Poa annua seedheads during spring can make putting greens slow and bumpy, frustrating golfers and turf managers. 

Many golf facilities could not avoid the temptation to open their doors during a recent stretch of balmy February weather. This was good news for golfers, but there were some concerns for turf managers. The potential for turf injury is one issue, but warm weather also creates concern about successful Poa annua seedhead suppression.

A surge in Poa annua seedheads during spring will make putting greens slow and bumpy. To prevent this problem, turf managers apply plant growth regulators (PGRs) to suppress seedhead emergence. Most use growing degree day (GDD) models to time initial PGR applications for seedhead suppression. However, GDD models assume a slow, steady temperature transition from late winter to early spring. Warm weather during late winter makes it difficult to determine the ideal time to initiate PGR applications.

Common sense and local knowledge may provide better guidance when GDD model predictions are compromised by warm winter weather. Monitor Poa annua located on a south-facing slope where soil temperatures rapidly increase during spring. Seedhead emergence on putting greens will lag behind seedhead emergence on south-facing slopes. When you see seedheads on south-facing slopes it is your cue to initiate PGR applications.    

Be sure to record the timing and success of PGR applications. Even if seedhead control is not ideal, the experience can provide a valuable resource for timing future applications.


Central Region Agronomists:

Bob Vavrek, regional director –

John Daniels, agronomist –

Zach Nicoludis, agronomist –

Information on the USGA’s Course Consulting Service 

Contact the Green Section Staff

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