Page 33 - Transitioning Turfgrass

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6 ETS Field Days
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Conversion Methods from Cool

Season to Warm Season Turfgrasses

Simone Magni, PhD, Centre for Research on Turfgrass for the Environment and Sports (CeRTES), Department
of Agriculture, Food and Environment, University of Pisa (Italy)

Maintaining a high quality cool season turfgrass fectiveness of a soft transition through the adjust-
in the transition zone of Europe is becoming an ment of ordinary treatments or through the devel-
increasingly difficult task due to conflicts between opment of new techniques.
high irrigation requirements and restrictions to One of the main issues is to complete the con-
water use, disease susceptibility and pesticide re- version while keeping the surface playable or with
duction policies. Thus, conversion to warm season the shortest period possible out of use. This implies
turfgrasses is becoming the preferred option by that the surface is not disrupted or only partially
turf managers. damaged during the sequence of treatments.
The simplest approach to the conversion of a Attempts to simply seed or sprig straight into an
pre-existent cool season turf into a new warm existing cool season turf while keeping the turf
season stand is to follow the ordinary technique growing have led to the establishment failure or
for turfgrass establishment. Chemical suppres- have no practical relevance.
sion and removal of the old turf, soil tillage, Scalping and verticutting before spreading the
post-planting or post-seeding chemical control of propagation material over the entire surface to
weeds and use suspension are standard steps to convert is a basic method to prepare the surface
accomplish the conversion. for broadcast seeding or broadcast sprigging (or
However, due to economic and environmental stolonizing). Cool season grass growth is tempo-
concerns, a “soft” or “smooth” transition approach rarily suppressed, seed or bud to soil contact is
is gaining popularity among turf managers. Re- enhanced enough to allow germination or sprout-
duced or nil soil tillage, minimal surface disrup- ing while canopy thinning allows a better light
tion, short period of use suspension with little or penetration.
no herbicide application are key practices of this Once the propagation material has generat-
approach that turn into cost savings and a more ed new plants the competition between the two
sustainable turfgrass management. grasses is the key factor in determining the final
Under a European perspective, the recent ban of composition of the stand, hence, treatments that
most of the chemicals from sports turfs has two are most inhibitory to the cool season turf are the
contrasting effects on the conversion to warm most beneficial in promoting the conversion to the
season grasses. On one side it makes conversion warm season stand. The suppressive effect on the
a more stringent choice for the need to abandon cool season species is then maintained with a low
the use of fungicides, while on the other side it cutting height, while the growth of the warm sea-
reduces the number of tools available to turf son grass is encouraged with repeated nitrogen
managers to complete the conversion by strongly fertilizations during summer.
reducing or eliminating the use of herbicides. In order to maximize the competitive effect of the
Investigations have been carried out in the last warm season over the cool season grass, the cor-
two decades with the aim of improving the ef- rect scheduling of seeding or sprigging is of para-

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