Australian Turfgrass Management Journal - Volume 20.1 (January-February 2018)

Page 18

GDD

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GDD

Jyri Kaapro conducted a workshop on Growing Degree Days at the 2016 Australian Turfgrass Conference in Melbourne

Dan Cook has successfully employed GDD modelling for Primo applications on his greens at Elanora Country Club over a number of years

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for other grasses including warm-season grasses like couch. Continued development will ensure the most appropriate models are quantified for different turfgrass species to ensure the prevention of over or under application of PGR. When it comes to GDD models, it is important to remember that although they serve as useful guides, they don’t replace scouting techniques or the observations of the turf manager. It is also important to note that for the most accurate GDD data, it’s recommended turf managers utilise an on-site weather station. That said, models such as this do serve as a guide to help turf managers compare month over month and year over year. In support of GDD usage, measuring and monitoring clipping yields is an excellent tool to calibrate the use of GDD to each situation. This can be done with the use of an indicator green.

AGRONOMIC STAPLE For Elanora Country Club superintendent Dan Cook, the concept of applying Primo Maxx using GDD

AUSTRALIAN TURFGRASS MANAGEMENT 20.1

modelling started back in 2009 after speaking to Dr Micah Woods (Asian Turfgrass Centre) while they were both volunteering at the Masters at Augusta National. Cook explains how after monitoring results and finetuning his approach, it has since become a key component of his agronomic programme at the Sydney course… “Since 2005 I have had several interesting agronomic discussions with Dr Micah Woods in regards to the management of bentgrass in Sydney. These conversations usually revolve around reducing stress on the plant during the summer months. I recall talking to him about the amount of nitrogen required by bentgrass in Sydney which quickly led to a conversation about Primo Maxx and its use. He had explained to me that there had been much research done in regard to how quickly Primo Maxx is used by the plant depending on air temperature. I had explained that I had always looked at my clipping yield daily and applied Primo at varying rates as required on a 14-day calendar. He asked how I accounted for the hot and cold days or, more to the point, how did I know what or how much Primo was left in the plant, or if the plant ever came out of growth regulation. After a pimento cheese sandwich and a Masters club during a lunch break at the 2009 US Masters where we were volunteering that year, he explained to me Primo Maxx applications can be calculated using Growing Degree Days. This pricked my ears up as the question I had posed to my staff about clipping yield is usually ‘Good morning, how much did you cut off your greens run today?’ which was usually answered with either ‘The same as yesterday’, ‘Not much’ or ‘Heaps!’ This proved quite difficult to schedule my Primo rate as the answers were not very definitive.