Green World

AN INDUSTRYWIDE PUBLICATION OF THE NEW JERSEY TURFGRASS ASSOCIATION

Volume 1, Number 3 

October, 1971

Dethatching Lawns

Dr. Henry W. Indyk1

Thatch is an accumulation of an 
undecomposed dense layer of organic 
matter on the soil surface in lawns. 
Contrary to popular opinion, thatch is 
not the result of failure to remove grass 
clippings. Grass clippings constitute 
only a small portion of the total thatch 
layer. Thatch is primarily composed 
of a dense mass of fibrous roots, rhi­
zomes (underground creeping stems) 
and stems of lawn grasses. Therefore, 
removal of grass clippings after mow­
ing in itself will not prevent the forma­
tion of a thatch layer.

Thatch will form sooner and to a 
greater extent in the better and more 
vigorous growing lawns. The thatch 
layer produces unfavorable conditions 
for growth of the roots of the lawn 
grasses. In a sense, it acts as a sheet 
of plastic covering the lawn. The 
movement of air, water, nutrients, and 
lime into the soil is severely restricted 
by a thatch layer. As a result, the lawn 
grasses tend to develop a shallow root 
system and a weakened top growth 
that is very slow in responding to prop­
er lawn care. In addition, the lawn 
grasses become more susceptible to 
drought, wear, invasion by weeds and 
to attacks by insects and/or diseases.
The thickness of the thatch layer 
can vary considerably from lawn to 
lawn. It may range from 1/4 inch to 
more than 2 inches. The thickness of 
the layer can be easily and simply de­
termined by examining a small square 
(2 to 4 inches) of sod from the lawn. 
The sod is obtained by cutting into the 
lawn with a sharp knife or garden 
spade to a depth of at least 3 inches 
and carefully removing. Examination 
of the side profile of the sample will 
indicate a rather sharp dividing line 
between the soil and thatch layer. The 
thatch layer will tend to be somewhat 
spongy and brownish in color with 
consistency resembling peat moss.
Extension Specialist in Turfgrass 
Management, Rutgers — The State 
University of New Jersey.

When the thickness of the layer is 
found to be greater than 1/2 inch, me­
chanical dethatching of the lawn will 
help in overcoming the detrimental 
effects of thatch. Various types of 
powered equipment are available for 
this purpose. They vary considerably 
in size, power, type of blades or tines, 
width between blades or tines, depth 
of penetration and the results achieved 
from their use. Many of the machines 
when used on a lawn will bring up im­
pressive amounts of dead material to 
the surface. Evaluation of the per­
formance of the machine on this basis 
can be very misleading. In order to 
be effective in relieving the effects of 
thatch, the machine must be adequate­
ly powered and capable of adjustment 
so that the blades or tines penetrate 
completely through the thatch layer 
and at least 1/2 inch into the soil with 
insignificant or no damage to the ex­
isting stand of lawn grasses. Removal 
of thatch material only from the sur­
face of the thatch layer is of little value.
Selection of the proper equipment 
becomes an important aspect of me­
chanical thatch control. Equipment 
presently available can be classified in­
to three basic categories as follows:

1.  Revolving spring tines.
2.  Revolving swinging blades.
3.  Revolving stationary blades.
Within these three basis categories,
many variations can be found. The 
machine with the revolving straight 
stationary blades that is adequately 
powered and capable of adjustment to 
penetrate through the thatch layer will 
produce the most effective and satis­
factory results in contending with 
thatch problems in lawns.

Dethatching of lawns should be re­
stricted to the seasons most favorable 
for growth of the lawn grasses. The 
early spring and fall are best for the 
cool-season grasses such as the Ken 
tucky bluegrass-red fescue type lawns 
and late spring or early summer for 
the warm-season grasses such as Zoysia 
and Bermudagrass. In comparing the 
favorable seasons, the fall is the pre- 
ferred time for the cool-season grasses

and the late spring for the warm-season 
grasses. Dethatching during the most 
favorable season will reduce the poten­
tial of damage to the desirable lawn 
grass. Furthermore, the lawn grasses 
recover immediately from any injury 
that may have been produced.

The suggested procedure for de­

thatching a lawn is as follows:
1.  Close mowing — if the topgrowth is 
more than 1 inch tall set mower 
cutting height at 1 inch, mow and 
remove clippings.

2.  Notate all areas that are bare or 

sparse and weak.

3.  Apply 25 pounds of ground lime­
stone and 10 pounds of a 10-6-4 
(50% organic fertilizer) per 1000 
square feet.

4.  Dethatch with thatching machine. 
Set adjustment on machine so that 
the blades penetrate through the 
thatch layer and at least 1/2 inch 
into the soil.

5.  Seed all bare and weak areas notat- 

ed above.

6.  Drag with steel door mat — may be 
repeated a second time. Before 
dragging, allow sufficient time for 
the loose thatch material and soil 
on the surface to thoroughly dry.

7.  Lightly rake thatch material remain­
ing on surface after dragging and 
remove from lawn. Thatch material 
may be composted for future use in 
garden or shrub beds.

8.  Thoroughly water.
Where Do Turfmen Stand On 
Growing Better Athletic Field Turf?

R. E. Engel

Most everyone accepts the value of 
turfgrasses to athletic fields because 
they offer: (1) safety over hard sur­
faces, (2) aesthetic value to player 
and spectator, (3) cleanliness to play­
ers, (4) and provide a medium that 
facilitates play of the sport. Yet, those 
of us who make turf growing our career 
will agree that athletic fields are too 
often needlessly poor. Many of the 
reasons are quite obvious to us, but a 
review of the general problem, causes,
and cures should bring some improve-
(Continued on next page)

The Causes of Poor Turf

What are the causes of poor turf on 
athletic fields? No single reason exists. 
Improper design and construction of 
the field is a major factor. The soil 
can have too much clay or sand for 
good results. Internal drainage of the 
subsoil is often too slow for good grass 
and early use after rains. Unfortunate­
ly some poorly drained fields continue 
in use for years without an attempt at 
correcting this basic need. Many fields 
have never grown a prime type of turf- 
grass species. With all the destruction 
of turf and reseeding that occurs on 
most fields, it would seem most fields 
would have the best grasses. Fields 
are often watered poorly. Some get 
too much, some are watered at the 
wrong time, and some are never wa­
tered. Certainly, any field of conse­
quence should have a grade A water­
ing system. The frequent need to ger­
minate turfgrass seedings and encour­
age regrowth as quickly as possible is 
adequate reason for developing a good 
system. Also, the inadequate systems 
are usually costly to set up and slow 
to apply the needed water at the right 
time.

Most athletic fields suffer from some­
thing less than good management. Too 
frequently, the field is of secondary in­
terest and receives part-time attention 
of persons who have a variety of other 
responsibilities. Even when persons 
are given clear responsibility for main­
tenance of the field, it is difficult to find 
personnel who have the know-how or 
interest. Most organizations must train 
their own men and pay good salaries, 
as well-trained turfmen are not com­
monly available because they have very 
good employment opportunities.

Maintenance deficiencies take many 
forms. A lack of adequate fertilization, 
mowing too closely or infrequently, 
failure to control weeds, incorrect use 
of herbicides, overwatering, and a lack 
of successful reseeding are common 
causes of failure. Of course, other fac­
tors can be responsible, but this listing 
is of great concern as it involves the 
common and basic needs.

Good athletic fields usually do not 
happen without a good budget and the 
stimulating spirit of a group who de­
sire a good field. Surprisingly few fields 
have an adequately prepared budget. 
In some cases, when equipment, inter­
est, and “know-how” are lacking, con­
tract maintenance may be the best 
choice. Most areas have capable con­
tractors. The problems with this pro­
cedure are: (1) determining the or­
ganizations that can maintain the field 
successfully, and (2) preparing speci­
fications that assure the competing bid­
ders will give equivalent performance.

How Much Should a Field Be Used?
Athletic fields are made to be used. 
The amount of use a field tolerates 
varies from season to season along with 
many other factors; and the appropri­
ate amount of use is difficult to deter­
mine. How important a given day’s 
use of the field may be is scarcely the 
turf grower’s prerogative. The growers 
do not wish to say that a major event 
should be held or postponed. Yet, the 
persons associated with turf and main­
taining the field are most aware of the 
ruinous tearing of the sod and soil 
compaction that occurs from use on a 
single day when conditions are im­
proper. Certainly, the turf grower 
should be consulted for an opinion as 
to the amount of harm that is likely 
to arise from use under difficult condi­
tions. Hopefully, administrators would 
not approve use of the field for sec­
ondary or trivial events when severe 
harm is imminent.

Improving Athletic Field Turf
The individual athletic field turf is 
often in need of several improvements. 
First, analyze the problem. What are 
the causes of poor turf? Attack the 
problems in order of importance and 
proper work sequence. Develop the 
interest and knowledge on the part of 
the working and supervising personnel. 
Install drainage if considered necessary 
by experts. Often the field should be 
recontoured. Reseeding or resodding 
of the field may be the next step. A 
good maintenance program should al­
ways follow. Good fields that are used 
seldom persist without regular repair. 
Even with the more severe conditions 
that destroy the grass cover, a field can 
develop an attractive cover of ryegrass 
with 8 weeks of nonuse, and cool, 
moist growing conditions.

Many athletic field areas do not have 
enough area to handle the total traffic. 
In such cases, additional grassed areas 
help maintain more continuous grass 
cover and aid the environment. Where 
space is very limited, a small portion 
of grassed area might be hard surfaced 
or covered with synthetic turf for use 
when the living grass areas need pro­
tection.

Develop a procedure for control of 
traffic. Unrestricted and continuous 
use or a day’s use under very destruc­
tive conditions can kill the stand of 
grass and necessitate long periods of 
delay before reusing the field. Some 
restriction of traffic before the turf 
cover is destroyed usually gives more 
total use of the grass than unrestricted 
use. Also, shifting the wear pattern 
will greatly increase total use. Of 
course, seedling turf or newly laid sod 
is destroyed with very little use. Such 
expenditure should not be made, unless 
proper protection is assured.

The maintenance program for the 
field should be a primary responsibility 
of one person who: (1) knows or 
learns the work; (2) has a major role 
in developing the program; (3) can 
stay with the work plus oversee labor; 
and (4) has a voice in proposing budget 
needs.

With regard to general needs for 
better athletic field turf, more research 
is needed. Our current choice between 
Kentucky bluegrass, perennial ryegrass, 
and tall fescue is helpful. Yet, some 
research on developing types that 
are tougher and establish quicker 
seems worthwhile. Research informa­
tion could help in developing more op­
timum soil mixtures. Also, research is 
needed on methods of growing vigorous 
grass but retaining tough leaf and stem 
tissue that resists more wear.

Synthetic Turf

Would turf growers ever propose the 
use of synthetic turf? Yes. This is 
the only hope for covered fields, sites 
with very limited facilities, and those 
that are used several times per week 
through most of the year. Yet, we 
urge careful study before converting to 
synthetic turf, as this does not appear 
to be the answer for many fields. The 
money spent on a synthetic field would 
be much greater than on the average 
grassed field. Installation costs of the 
synthetic field, even spread over a 10- 
year period, will do a tremendous 
amount of additional grass mainte­
nance that most fields have not re­
ceived previously. Also, the synthetic 
field is not free of maintenance costs. 
The player injury relationship between 
grass and synthetic turf is not clear. 
Synthetic turf is considerably hotter 
for summer use. Also, it does nothing 
to aid the environment.

In conclusion, athletic fields offer 
considerable opportunity for improve­
ment. Everyone with responsibility for 
some part of the field’s development 
or use, whether he be a turf grower, 
public official, architect, contractor, or 
commercial supplier, should recheck 
their role in providing for the proper 
needs of athletic fields. The needs are 
not ending; they are growing. The 
athletic field is in frequent need of 
extra care or rejuvenation. Grass will 
be the playing surface for many years 
on most athletic fields. We should find 
ways to encourage better turf for so 
many of these neglected areas where 
nothing but the best should be ac­
cepted. 

ARTICLES WANTED 
Send to: Box 123 
Caldwell, N. J. 07006

ATHLETIC FIELD CONSTRUCTION

(1)

(3)

(5)

(2)

(4)

1.  Baseball field roughed out and ready for sand-clay place­

ment in baselines.

2.  Rocks and debris shown above could have been avoided 
by enforcement of proper contractual specifications, in­
cluding normally required hand work.

3.  Uniform application of proper nutrients and soil amend­

ments is too often overlooked.

4.  Machine in foreground meters exact seed required over 
given area and sets same directly into soil at acceptable 
depth.

5.  Completed athletic area now awaits the care of Mother 

Nature and hopefully a good maintenance program.

Change In Name,
Adelphi Kentucky Bluegrass

Due to prior usage of the name as a 
brand mixture, Nassau, which had 
been approved by the U.S.D.A. and 
assigned to the new experimental Ken­
tucky Bluegrass variety P-69 or FS- 
200, has been changed to ADELPHI 
KENTUCKY BLUEGRASS. The re­
sponsibility for the need to make this 
change naturally rests with the namer 
and not with the U.S.D.A.

Adelphi is a very appropriate name 
for this new variety; the connecting of 
the very oldest and best with the new­
est and most outstanding. It is at Adel­
phi, where for many years we have 
seen some of the most beautiful lawns 
in existence. In addition, it was at 
Adelphia Breeding Station of Rutgers 
University that work was done on the 
new variety Adelphi.

The variety Adelphi has been tested 
over a six-year period and has con­
sistently been given a better quality 
and performance rating than other 
bluegrasses currently in widespread 
use. It has an attractive, rich, deep, 
dark green color, which it maintains 
throughout the growing season, hav­
ing good resistance to leaf spot, crown 
rot, leaf rust and stripe smut. Under 
turf maintenance it has good rhizome 
and tiller development, producing an 
eye-appealing turf of excellent density 
and moderate horizontal spreading 
ability. The variety Adelphi will also 
tolerate moderately close mowing.

History is being made in the seed 
industry with this new variety, Adelphi 
Kentucky Bluegrass, as it is the first 
man-made or man-propagated strain 
to be marketed. The development and 
breeding work was done by Dr. C. 
Reed Funk and Dr. Gerard W. Pepin 
at Rutgers University. Adelphi Ken­
tucky Bluegrass selected as the best 
from literally thousands of new vari­
eties, based on overall performance 
coupled with the ability to produce 
marketable seed, is only the beginning 
of the advent of a whole new surge of 
improved varieties which will be com­
ing on the market due to the fine work 
of these two men.

A limited quantity of Adelphi Ken­
tucky Bluegrass seed was available last 
year, which was used mainly to extend 
the testing program of the variety in 
the East. While more seed is available 
this Fall, again, most of the quantity 
will go to selected locations so that 
plantings may be controlled and ob­
served under a wide and varied range 
of growing conditions. It is anticipated 
that the variety will be freely available 
to the general public in the Fall of 
next year.

The United States marketing will be

handled by J & L Adikes, Inc., Jona­
than Green & Sons, Inc. and The 
Vaughan Seed Company.

Rooting Ability of Merion Kentucky 
Bluegrass Sod Grown on Mineral 
and Muck Soil

J. H. Dunn and R. E. Engel 

Agronomy Journal 62:517-520, 1970
Merion Kentucky bluegrass sod 
grown on muck or mineral soil in sev­
eral Northeast and Midwest states was 
subjected to field tests to show resist­
ance of the newly planted sod to hori­
zontal shearing. Sod rooting as meas­
ured by resistance to shearing varied 
more by sod source than by muck or 
mineral soil origin. In tests planted on 
June 3 and July 20, mineral sod ap­
peared to have better resistance to 
shearing; while measurements for this 
same character in a third test of July 
28, the muck sod was equal to the min­
eral sod. In a greenhouse test of sam­
ples used in the third test, the cultures 
planted with muck sod had some ad­
vantage in new root growth at 11 days 
over those grown with mineral sod. As 
a group, those sods with well-devel­
oped rhizome systems did not show 
better rooting. Thin cut sod (3/4") 
had consistently higher shear strength 
than sod cut to l 1/2".

Comments: This research report 
shows muck and mineral sods may not 
differ as much in early rooting be­
havior as often expected. These results 
agree well with information from Mich­
igan State University. Of course, more 
data are needed on: (1) the cleavage 
line phenomenon between sod and nat­
ural soil, and (2) the relationships of 
high organic soil, thatch, and rewetting 
as occurs when muck soil is placed on 
a mineral soil. Some historical think­
ing proposed avoiding muck sod on 
heavy traffic areas, slopes, or greens 
where turfgrass survival can be diffi­
cult. Possibly some of these consid­
erations on the choice of muck or min­
eral sod may still be appropriate. Data 
from this study support thin cutting of 
sod. Thus, using thin sod should re­
duce the theorized problems from the 
very different layer of soil introduced 
with the sod whether it originates from 
a muck soil or a mineral soil with gross­
ly different physical characteristics.

Intraspecific Hybridization as a 
Method of Breeding Kentucky 
Bluegrass for Turf

G. W. Pepin and C. R. Funk
Crop Science 11:445-448, 1971 
Four selections and one cultivar in
Kentucky bluegrass were crraey ir> 
various combinations. The most vig-
orous of the resulting hybrids were 
selected for evaluation of turf perform­

 

ance. After 2 years of observation in 
turf trials, the 17 most promising turf- 
type hybrids were studied in greater 
detail. Eight hybrids were highly ap- 
omictic, and were equal or superior to 
their parents in a number of character­
istics reflecting vegetative and repro­
ductive vigor, disease resistance and 
turf performance. Many of the most 
promising hybrids appeared to be tri- 
ploids resulting from the fertilization 
of unreduced female gametes.

Comments: Obtaining improved turf­
grass types of Kentucky bluegrass 
through selection and breeding was 
oftentimes considered unpromising. Se­
lection of Merion Kentucky bluegrass 
and its subsequent usefulness showed 
one part of the fallacy. This paper 
shows that crossing of complementary 
types and selecting among the progeny 
is also an open avenue to better Ken­
tucky bluegrasses for turf.

RAPP FARMS INC. 

Cultivated Sod

N. J. State Certified

(201) 938-6911 

FARMINGDALE, N. J.

SNOW MOLD PROTECTION

“SNO-CHEK”: granular mercury —48# 
drum treats 6000 sq. ft
“CLEARY’S GRANULAR”: Thiram-Cad- 
mium —20# bag treats 5000 sq. ft.

ALSO

“PMAS,” “CADDY” & “CLEAR-SPRAY.” 
To get longer residual and Winter Kill 
protection add Clear-Spray in your pro­
gram as a sticker.

W. A. CLEARY CORP.

LOFTS PEDIGREED SEED, 

INC.

Growers and Marketers of

BARON Kentucky Bluegrass, Manhattan 
Turf-Type Perennial Ryegrass, James­
town Red Fescue and other improved 
turf grasses. 

356-8700

BOUND BROOK, NEW JERSEY