Environmental Engineering Reference
In-Depth Information
alternative to foliar application of chelated iron, mentioned in Chapter 5,
for short-term improvement of turf appearance.
Plant Growth Regulators
Plant growth regulators (PGRs) are naturally produced chemicals that
alter growth of the plant by inhibiting or promoting division, elongation
and differentiation of cells. In the turf-grass industry, synthetic PGRs
have been used since the 1970s to restrain turf-grass flowering (produc-
tion of seed-heads), as well as to slow down growth and therefore to
reduce the need for frequent mowing. PGRs are appreciated in tropical
climates, where growth of turf-grasses is vigorous and mowing is needed
year-round. The primary problems with most PGRs have been phyto-
toxicity and inconsistency in response. Physiological and morphological
differences between turf-grass species or even varieties, diverse environ-
mental conditions and unpredictable weather patterns result in inconsist-
ent responses by the plants, and make establishment of rates and
application recommendations difficult. Besides these imperfections,
PGRs are still expensive and require frequent applications (usually 6-8
times a year) and long-term commitment. If an application programme is
begun, it should be continued; otherwise, when PGR treatment wears off,
tremendous growth surges occur, making mowing even more frequent
and burdensome. In addition, if damaged by diseases, insects, scalping or
any other type of stress, PGR-treated turf takes much longer to recover.
Progress in PGR development is continuous. Recent products are less
phytotoxic and more reliable. Although PGRs will never replace mowing,
the 50-70% reduction they provide can save considerable amounts in
labour costs.
Like other chemical agents, PGRs must be applied strictly according
to the label recommendations. Just like pesticides, if misused, they can
contaminate ground water and prove toxic to animals, aquatic wildlife,
pollinating insects, etc.
Mowing Equipment
Several basic types of mowers are available. The most accurate are reel
mowers, rotary mowers are intermediate and sickle-bar mowers are the
least precise. A fourth type, commonly called vertical mowers, are used
to slice turf vertically rather than to remove the tops of the leaf blades and
will be discussed in Chapter 8.
The proper choice of mowing equipment depends on the type of
grass and the conditions of usage and maintenance. Sharp, properly
