30 SportsTurf | August 2016 www.sportsturfonline.com
FIELD SCIENCE
rates, indicated on the label use instructions. Very often, labels
recommend a range of rates. The recommendations listed here
provide examples of when one might apply low or higher rates.)
This includes actively growing, semi-dormant and dormant
turfgrasses.
Stage of growth. Dormant and semi-dormant turfgrasses
require higher rates of the same colorant. Always test a small
area before applying to dormant turfgrass. I recommend
applying pigments, and even paints, to semi-dormant
turfgrass, rather than plants that have reached dormancy (see
'Are Colorants Absorbed by Leaf Tissue?' page 30 for more
information). In our experience this approach produces a better
color at lower rates and requires fewer subsequent applications
during the dormancy period.
Water carrier. We found that colorants perform the best
at a wide range of water volumes anywhere from 88 to 150
gallons per acre (GPA). Research as shown, however, that turf
color and longevity will increase by using higher water carrier
volumes– up to 160 GPA.
Height of cut. Regardless of species, cultivar, or hybrid, grass
mowed higher will require higher rates of the same colorant.
At the higher height of cut, more leaf surface area will require
more material to achieve the same level of uniformity and
ultimately, color.
Colorant formulation. Clearly, formulations differ in their
concentration and inert ingredients, which determine optimum
use rates.
ARE COLORANTS ABSORBED BY LEAF TISSUE?
The short answer is likely yes, but we cannot be entirely
sure. Most currently believe colorants coat the leaf surface
and remain there until being mowed off. However, anecdotal
evidence and observation might suggest that pigments are, in
fact, absorbed. For example:
■ Excellent color can be maintained for 2-3 weeks after
repeated mowing, depending upon rate.
■ Different turf response was observed when colorants were
applied to dormant and semi- dormant bermudagrass.
Based on our work, and I'll say it again, it's best to apply
colorants before the turf is fully dormant, or straw-colored.
Miller and Pinnix made a similar observation in 2014.
These observations suggest that if/when pigment
formulations get into the plant, color longevity, use rate and
application frequency are impacted. McCarty et al., 2013
argued that paints are not absorbed by leaf tissue, while
pigments are absorbed through stomata. More research will
help clarify this question and before we can make a fi rm
conclusion about colorant absorption by turfgrass leaf tissue.
Will paint colorants rub off on players' uniforms during
games? Based on our research and practically speaking, I
think not. We tested the dry time of paint applied to Kentucky
bluegrass under different atmospheric conditions and found that
the dry time was very fast, no longer than 26 minutes.
