10 SportsTurf | May 2016 www.sportsturfonline.com
FIELD SCIENCE
will help alleviate added
stresses to the turf already
under shade stress conditions.
Trees are usually the major
cause for shade problems,
especially in golf course situa-
tions. Unfortunately, trees are
also an important component
to the golf course landscape.
Trees add depth and aesthetic
value to complement any golf
course design. However, trees
can also grow to exceed their
original benefit and cause problems such as turfgrass shade
stress. If the tree causing the shade cannot be removed, pruning
both the limbs and roots will help reduce some of the problems
being caused to the turf. Pruning the limbs will allow for more
light to penetrate to the turf surface, and root pruning will lessen
the competition for nutrients and water. Several research studies
have been conducted to show the benefits of using plant growth
regulators (PGRs) on turf under shade stress conditions. Stier
and Rogers (2001) found that the use of PGRs like Trinexapac
Ethyl (Primo), have shown to limit shoot elongation and im-
prove photosynthetic efficiency (Figure 1). Finally, when at all
possible, any attempts to provide morning light will greatly help
with dealing with shade stress conditions. Morning light is when
cool-season photosynthesis is at is greatest; thus, enabling for
maximum photosynthetic efficiency.
Selecting the proper turfgrass species is one of the most
important decisions to make when trying to manage turfgrass
in shade. Unfortunately for golf course putting greens turfgrass
PHOTO
COURTESY
OF
SIMON
GUMBRILL
OF
STADIUM
GROW
LIGHTING.
species selection is limited;
however, for tees and roughs
using a turf well adapted
to shade will significantly
improve your turf quality and
golf course conditions. Poa
supine is one of the best, if not
the best turfgrass for shade
situations. A native turf of
Austria, Poa supine is well
adapted to cool climates and
performs exceptionally well
in the shade.
More then 140 stadiums worldwide use grow lights to
compensate for shade stress conditions. These lighting systems
use high-pressure sodium (HPS) lights similar to grow lights
used in greenhouses. Another benefit from the HPS lights are
the increased temperatures under the lights which also improves
growing conditions for stadiums in cool climates, like Lambeau
Field in Green Bay, WI.
In conclusion, turfgrass management under low light/shade
is common in many sports turf situations and an understanding
of the cause and effects of shade stress can help a turfgrass
manager improve turfgrass conditions in the shade.
John Sorochan, PhD, is Distinguished
Professor-Turfgrass Science and
Co-Director for the Center for
Athletic Field Safety at the
University of Tennessee in Knoxville.
Fig. 1. Effect of PGRs on Pn in reduced light conditions (3.5 mols PAR day-1) Nov. 1996
