The warm temperatures we've experienced this month tells us spring will be here shortly. Although the turf has not come out of dormancy, I'm already thinking about Poa annua seedhead suppression. Seedheads will not appear until May, but multiple growth regulator applications will be made before then to ensure the putting surfaces are pristine.
One way turf managers try to predict seedhead emergence is by monitoring growing degree days (GDD). GDD models have been developed to determine the best time to apply growth regulators to control the prolific seedheads that Poa annua produces each spring.
What are Growing Degree Days (GDD)?
The sum of the number of degrees by which each day's average temperature exceeds a base temperature (32F).
How are GDD calculated?
GDD = [(maximum temperature + minimum temperature) / 2] - (32)
For example on March 11, the high of 54F and a low of 37F resulted in a GDD of 14.
I keep track of the GDD accumulation and base my seedhead suppression applications on a GDD model I've developed over the last five years. Sprays will not begin until we have accumulated 200 GDD. Below is spreadsheet of the GDD accumulated this month.
One way turf managers try to predict seedhead emergence is by monitoring growing degree days (GDD). GDD models have been developed to determine the best time to apply growth regulators to control the prolific seedheads that Poa annua produces each spring.
What are Growing Degree Days (GDD)?
The sum of the number of degrees by which each day's average temperature exceeds a base temperature (32F).
How are GDD calculated?
GDD = [(maximum temperature + minimum temperature) / 2] - (32)
For example on March 11, the high of 54F and a low of 37F resulted in a GDD of 14.
GDD = [(54+37)/2] - 32
I keep track of the GDD accumulation and base my seedhead suppression applications on a GDD model I've developed over the last five years. Sprays will not begin until we have accumulated 200 GDD. Below is spreadsheet of the GDD accumulated this month.
