Vol. 16—1962 - NorthEastern Weed Science Society

It might dispel some confusion here to hazard &1'1opinion, shared by
numerous turf specialists, regarding fertilizer usage. - Manydifferent grades
and formulations of fertilizers can be used successfully in a turf management
program. The~e is nQ single grade ,brand, or type that is yet recognized' as
being superior oV4trall. Certain ratios are often given as guides and application
rates are suggested but beyond this it has been Clearly demonstrated- that
dense, vigorous turf can be maintained with many different grades and formulations
of complete fertilizers.
Perhaps it should be made clear also that too much fertilizer can be as
damaging to ~ maintenance program as too little or none at all.
There should be little doubt anymore that cutt£ng height of turfgrasses
is a critical consideration in the management of lawns. Numerous studies have
clearly indicated a close correlation between heig/ltof cut and depth and extent
of rooting. Qoberts and Bredakis .(12), in a rtport from Massachusetts in
1960, reviewed 35 years of root studies. A number of concjusdcns were drawn
on the basis: of these many studies. A very important-one is as followsl
"Regardless of the type of grass under experimentation, clipping or defoliation
at regUlar intervals inhibits the development of new roots in comparison ~th
nonclipped tu;rf. ·Onmost species and strains this reduction in root development
becomes progressively greater as the height is·'lClWered"•
. There are differences in cutting height ·to1erance among the genera,
species or varieties of lawn graScS8s. These have been pretty well detennined
and every article on cutting management suggests minimumcutting heights for
the various grasses. Grasses that are cut consistentJy, shorter than suggested
invariably become weaker and are less able to compete with weeds. In addition
to this,grasses weakened by too clos.e mowing are; 1_" able to tolerate herbicide
treatment. The problems encountered in treating close-cut golf course' ­
turf with herbicides Is a good example.
Another facet of cutting height relates to weed seed germination.
Ught intensity minimumsmust be exceeded before certain weed seeds can
germinate •. T,1'leCOllllllOn crabgrasses, for instance, do' not germinate or grow 11'1'
fairly shaded areu. Keeping the soil surface shaded by maintaining a dense
turf, cut at recommended heights most assuredly aide In reducing the weed
popUlation.
Water usage in turf management is important in +ooeedcontrol. It has been'
very. enlightening to me to see firsthand many clear cases of weed infestation
positively correla~ed with improper water usage. This has been most Clearly'
shown following. the installation of irrigation systems on golf courses and
home.lawns •.. .fQai!3mIi' crabgrass, bentgrass and evetta few of the broad1eaved.
weeds often flourish and gain the ~pperhand within two or three years fo~Xowin9
the install.ation of irrigation systems. This is particuLarly the case whe~
the grass is cut too short, is thin, or the water is 'applied lightly and 'fr$quently.
It is likely that an increased incidence of disease is many timel!;'an'
intermediaryin-re,pect to turf density, water usage and weed population. In.
overly ..wet ..collditions.disease ismClre prevalent and damaging and frequently'
thins the turf open:l:ng it up for invasion by weeds. ' .