PETER McMAUGH
Spring
root dieback Recently anointed Member of the Order of Australia recipient Peter McMaugh looks back on one of the great pieces of turfgrass research which is still relevant more than 30 years after its findings were released.
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n the eulogy article I wrote for Dr Jim Beard in ATM Volume 20.4 (JulyAugust 2018), I mentioned in passing what I considered one of his greatest contributions to turfgrass science, the phenomenon of spring root dieback in warm-season grasses. He first presented this research to the international turfgrass community at the 5th International Turfgrass Research Conference at Avignon, France in 1985. This was no fly-by-night piece of research. It had been carefully and methodically researched by Jim for over eight years prior to this presentation and continued on for at least another six years. The success of this study was due mainly to the innovative ‘rhizotron’ construction that Jim was able to build at Texas A&M University (see photo top of page 42). The following description of the rhizotron is taken from the ‘Materials and Methods’ section of the paper presented in Avignon in the conference proceedings (p.777ff by S.I. Sifers, J.B. Beard and J.M. DiPaola.) “The Texas A&M Turfgrass Rhizotron consists of a 48 compartment subterranean observation chamber with two rows of 24 glass-faced root observation boxes separated by a work space. Each of the 25cm wide by 75cm deep boxes had a slanted glass face, 0.64cm thick, through which root observations were made. The glass face was kept dark and insulated with 2.5cm thick polyurethane pads during non-observation periods. “Root extension lengths were recorded daily by tracing new root growth on clear acetate sheets which were pressed against the glass plate. Soil temperatures were continuously monitored within four randomly selected boxes at 10 and 30cm depths (Di Paola et al, 1982). Soil temperatures within the boxes were found to be the same as those in an adjacent undisturbed turf area.” 42
The big advantage of this type of construction is that it allowed the experimenter to see in real time the real life-size root volume of the sward without disturbance of the profile. These windows were used only for periodic viewing and were not permanently open. This was not an original concept but one adapted to turfgrass research from previous studies of the roots of fruit trees. This is a very important way to study plants because roots do not form or follow their normal patterns of growth in the presence of light. If you are doing any meaningful root studies they have to be done in the dark which is how they grow naturally. The next thing to note about this study was that it was a long-term one. It is very hard to overestimate the value of long-term studies in turf or, for that matter, agriculture in general. Historically this has been amply illustrated by the long-term pasture plots at Rothamsted Research Station in the U.K. The fame of these is world renowned and their value is incalculable. In the early days of turf research there were many long-term field lots at the USDA experiment stations and botanic gardens throughout the USA. I was lucky to inherit such a one at the Ryde School of Horticulture when I started in turf research. Today, sadly, they are considered too costly to run and most have disappeared. You simply can’t draw long-term implications from short-term studies. Long-term studies have a life of their own and they show up interactions that we often don’t expect and certainly can’t anticipate.
IMPORTANT FINDINGS Realising how important this spring root dieback research was and the groundbreaking nature of its message, I urged the
AUSTRALIAN TURFGRASS MANAGEMENT 21.3