18 Green Media / August 2014 www.greenmediaonline.com
Germination, establishment and
cover development in turf
Canopy refl ectance can be used to track the establish-
ment of newly seeded turf. In research trials, we can use this
to assess different cultivars, blends and mixtures, or different
management techniques in establishment. Fig. 7 shows cover
development in a recent trial at the GTI, and Fig. 8 shows
the change in canopy refl ectance in one of the entries over
the fi rst 26 days after seeding. Fig. 9 shows data from an
earlier trial, in this case using the chlorophyll index rather
than NDVI. Sixteen Kentucky bluegrass cultivars show clear
differences in speed of establishment as measured by canopy
refl ectance.
Drought stress, water use and localized dry spot
Fig. 10 shows localized dry spot and treatment effects of
wetting agents in a recent trial. If we look at the canopy re-
fl ectance and independent assessments of soil moisture (Fig.
11) and localized dry spot (Fig. 12), the potential of canopy
refl ectance to detect and help manage water problems is clear.
We have also used the technique in assessing the effectiveness
of different irrigation regimes in establishing turf from dry
seeding, hydroseeding, and sod.
Other biotic and abiotic stresses
As mentioned above, many stresses that affect turfgrass
will be detectable in changes in canopy refl ectance. We
routinely use the technique in assessing trials involving
dollar spot disease, for example. Fig. 13 shows symptoms
of dollar spot as they develop in a recent trial, and Fig. 14
shows how the disease pressure shows up in the canopy
refl ectance data.
What's needed before the tools are widely used by
turf managers?
Experience. We need to have a better grasp of how the
numbers change across species, management conditions,
etc. It is a very young technique outside of research ap-
plications.
Calibration. The sensitivity of the tool to so many factors
means that in order to isolate effects of interest, we need to
learn to calibrate to remove extraneous noise (we use un-
treated control plots in research, and similar techniques can
be used in management).
History. The more the tools are used on a particular turf
area, the better the information. The advantage of these
tools is that they automatically record and time-stamp the
TURFGRASS MANAGEMENT TURFGRASS MANAGEMENT
Figure 7. Cover development in turf trial.
Figure 8. Increase in canopy refl ectance with germination and
cover development in seeded turf.
Figure 10. Localized dry spot in bentgrass turf; some plots are
treated with wetting agents.
Figure 9. Association between grass cover and canopy refl ectance
(chlorophyll index) in Kentucky bluegrass cultivars.
26 days after seeding
16 days after seeding
7 days after seeding
