1994

Iowa Turfgrass

Research Report
■ *t

Department of Horticulture
Department of Plant Pathology
Department of Entomology
Cooperative Extension
IOWA STATE UNIVERSITY
In Cooperation with the
Iowa Turfgrass Institute

Io w a S t a t e U n i v e r s i t y
OF S C I E N C E A ND T E C H N O L O G Y

BEARD

COLLECTION

University Extension

F G -4 6 2 I J u ly 1 9 9 4

Introduction
N. E. Christians

The following research report is the 15th yearly publication of the results of turfgrass research projects
performed at Iowa State University. Copies of information in earlier reports are available from most
of the county extension offices in Iowa.
The 1993 season was one of the wettest in history. The response of several cultivars was different in
1993 than were the responses observed in more normal years. Turf response to fertilizer, herbicide
and growth regulator treatments were also affected by the unusual weather. It is recommended that
those who use the report to make decisions on the selection of grasses or pesticide products also refer
to previous reports when making critical decisions.
For the fourth year, this research report contains a section titled "Environmental Research." This
section is included to inform the public of our many research projects that are aimed at the many
environmental issues that face the turf industry. In the past four years this has become a major thrust
of the research program and many of our more extensive, in-depth projects are now aimed at
environmental issues.
I would like to acknowledge Dr. Mike Agnew, who left Iowa State University in February, 1994, for
his work on the projects reviewed in this report and for all of his contributions to the turf industry in
the past 10 years. Mike will be missed by his coworkers at Iowa State University and by all of those
involved in the Iowa turfgrass industry.
I would like to acknowledge Richard Moore, interim superintendent of the ISU Horticulture Research
Station; Jim Dickson, interim manager of the turf research area; Dave Anderson, graduate research
assistant; Dianna Liu, Post Doctoral researcher; Barbara Bingaman, Post Doctoral researcher; Doug
Campbell, research associate, and all others employed at the field research area in the past year for
their efforts in building the turf program.
Special thanks to Lori Westrum for her work in typing and helping to edit this publication.
Edited by Nick Christians, professor, Horticulture.

Table of Contents

Turfgrass Research Area Maps
Environmental Data

1
4

Species and Cultivar Trials
Results of Kentucky Bluegrass Regional Cultivar Trials - 1993

7

The Recovery of Kentucky Bluegrass Cultivars Following
Summer Dormancy - 1993

14

National Perennial Ryegrass Study - 1993

15

Regional Fine Fescue Cultivar Evaluation - 1993

18

Shade Adaptation Study - 1993

21

USGA Buffalograss Trial - 1993

23

Alkaligrass Evaluations - 1993

24

Green Height Bentgrass Cultivar Trial (Native Soil) - 1993

25

Fairway Height Bentgrass Study - 1993

26

Herbicide and Growth Regulator Studies
1993 Preemergence Annual Grass Control Study

27

1993 Postemergence and Preemergence Annual Grass Control Study

30

1993 Broadleaf Weed Control Study

31

The Effects of High and Low Nitrogen Regimes on the Response of
Creeping Bentgrass and Kentucky Bluegrass to Growth Regulating Compounds

32

The Rooting of Creeping Bentgrass and Kentucky Bluegrass Treated
with Growth Regulating Compounds

36

Primo Grass Seed Germination Study - 1993

39

1993 Ciba Primo Study

42

The Effect of Ethofumesate (Prograss) on a Putting Green
at Veenker Memorial Golf Course in Ames, Iowa

47

Turfgrass Disease and Insect Research
Evaluation of Fungicides for Control of Snow Molds on Creeping
Bentgrass, 1993-1994

49

Evaluation of Fungicides for Control of Brown Patch in Creeping
Bentgrass - 1993

51

Evaluation of Fungicides for Control of Dollar Spot in ’Penncross’
Bentgrass - 1993

53

Evaluation of Fungicides for Control of Leaf Spot in ’Park’
Bluegrass - 1993

55

Potential Control of Symptom Expression by Leaf Spotted
(
Bipolarissorokiniana) Kentucky Bluegrass Leaves

57

The Screening of Allelopathic Compounds as Potential Herbicides

61

Fertilizer Trials and Soil Studies
Natural Organic Source Study

65

Fertilizer Rate Evaluation

68

UHS Controlled Release Nitrogen Study

72

Scott’s Poly-S Study

74

Plant Response to Nitrogen Source

77

The Effects of Soil Compaction on Soil Physical Properties and
Plant Growth of Five Cultivais of Tall Fescue

80

Environmental Research
Fate of Nitrogen, Phosphorus, Pendimethalin, Chlorpyrifos,
Isazofos, Metalaxyl, Dicamba, 2,4-D, and MCPP Applied to
Turfgrass Maintained in Golf Course Fairway Condition

83

Herbicidal Activity of Hydrolysed Com Gluten Meal on
Three Grass Species under Controlled Environments

84

Isolation and Identification of Root-Inhibiting
Compounds from Corn Gluten Hydrolysate

85

Evaluation of Com Gluten Meal as a Natural Weed Control
Product Under Greenhouse Conditions

86

Environmental Research - cont.
A Study on the Effects of Com Gluten Meal and Corn Gluten
Hydrolysate on the Establishment of Agrostis Palustris

88

Innovative Production Techniques for Shade and Ornamental Trees

90

Determination of the Site of Action of a Root Inhibiting Compound
Derived from Corn Gluten Meal

92

The Use of a Natural Product for the Preemergence Control of
Annual Weeds

93

Introducing
The Iowa State University Personnel affiliated with the Turfgrass
Research Program

95

Companies and Organizations that made donations or supplied products
to the Iowa State University Turfgrass Research Program

97

Turfgrass Research
Area Maps

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Environmental Data

Annual Progress Report
Iowa State University Horticulture Research Station
Ames,Iowa

Crop Season
Monthly average rainfall, temperature and days with rain for the Horticulture Research Station, Ames, IA,
are listed in the table below. The 1993 growing season was cold and wet. From the end of June until
late September, the unrelenting rains caused the worst production disaster in the history of the state. In
addition, September was the coldest on record. Most areas of the state suffered near total losses.
The last spring frost was April 22, 1993. The minimum temperature in May 1993, was 36°F, occurring
on May 22. The first fall frost occurred on October 3, 1993. The respective normal 25% chance of frost
is May 9 and October 6.

Weather data for 1993, Iowa State University Horticulture Research Station, Ames, Iowa.
Rainfall (inches)

Temperature(°F)

Average

Deviation
from Normal

Average

Deviation
from Normal

Number of
Rain Days

April

45

-8

2.50

-0.69

13

May

59

-2

5.80

+1.30

15

June

69

-1

8.48

+2.68

13

July

71

-4

19.68

+16.44

16

August

71

-1

16.18

+12.53

20

September

59

-6

4.30

+1.10

10

Month

4

8

S3 H 0 N I

5

DAILY RAINFALL - A M E S

Solid Une = M ax Dashed Une

DAILY TEM PERATURE - A M E S

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II

8 8 8 8 8 8 8 8 8 8 8

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6

°

°

Species and Cultivar
Trials

Results of Kentucky
Bluegrass Regional Cultivar Trials - 1993
N. E. Christians and J. D. Dickson

The United States Department of Agriculture (USDA) has sponsored several regional Kentucky
bluegrass cultivar trials conducted at most of the northern agricultural experiment stations. The current
test consists of 62, 80, or 128 cultivars; the number depending on the year of establishment and the
type of trial, with each cultivar replicated three times.
Three trials were underway at Iowa State University during the 1993 season. A high-maintenance
study was established in 1990 that receives 4 lb N/1000 ft2/yr and is irrigated as needed. The second
trial was established in 1985 and receives 4 lb N/1000 ft2/yr, but is non-irrigated. The third trial was
established in the fall of 1991 and is a low-maintenance study that receives 1 lb of N/1000 ftVyr in
September and is non-irrigated. The objective of the high-maintenance study is to investigate cultivar
performance under a cultural regime similar to that used on irrigated home lawns in Iowa. The
objective of the second study is to observe the cultivar response under conditions similar to those
found in non-irrigated lawns that receive a standard lawn care program. The objective of the third
study is to evaluate cultivars under conditions similar to those maintained in a park or school ground.
The values listed under each month in Tables 1, 2 and 3 are the averages of visual quality ratings
made on three replicated plots for the three studies. Visual quality was based on a scale of 9 to 1: 9
= best quality, 6 = acceptable quality, and 1 = poorest quality. Yearly means of data from each month
were taken and are listed in the last column. The first cultivar received the highest average rating for
the entire 1993 season. The cultivars are listed in descending order of average quality.
Because of the very wet conditions in 1993, irrigation was not necessary during the season and the
non-irrigated plots received the same moisture as the irrigated plots. Of particular interest in the 1993
data is the ranking of the varieties in the low maintenance trials. Low maintenance cultivars like
Kenblue and South Dakota Certified generally rank high in non-irrigated studies. In this very wet
year, however, these cultivars ranked much lower than in dryer years (Table 2).

Table 1. The 1993 quality ratings for the high-maintenance, irrigated Kentucky bluegrass trial.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

Cultivar
Conni
Apex (Summit)
BA 77-279
Alpine
BA 70-131
Blacksburg
Glade
Midnight
PST-0514
WW AG 505
Able I
Allure (BA 73-540)
Cynthia
Limousine
Miracle
Ampellia

May
8.0
7.0
6.7
7.7
7.3
7.3
7.7
7.7
7.7
6.3
7.7
6.7
6.7
7.0
6.7
7.3

June
8.0
7.3
7.7
7.7
7.0
7.7
7.0
7.0
8.0
8.0
7.7
7.7
7.3
7.7
7.3
7.0

July
8.3
8.3
8.3
7.0
7.3
7.7
7.7
7.3
7.0
8.3
7.0
7.3
8.3
8.0
7.7
7.3
7

Aug
7.3
7.3
8.0
8.0
7.3
7.7
8.0
7.7
8.0
7.3
7.3
7.0
7.0
7.5
7.3
7.7

Sept
7.3
7.7
7.3
7.0
7.7
7.0
7.0
7.3
7.0
7.0
7.0
7.0
6.0
6.0
7.7
6.7

Oct
7.3
7.7
7.0
7.0
7.7
7.3
7.5
7.3
7.0
7.3
7.0
7.7
7.0
7.3
7.0
7.0

Mean
7.7
7.6
7.5
7.4
7.4
7.4
7.4
7.4
7.4
7.4
7.3
7.3
7.3
7.3
7.3
7.2

17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

Cultivar
Eagleton
Eclipse
Entry 127
Estate
EVE 13.703
PST-1DW
PST-C-224
WW AG 508
Aspen
BAR VB 852 (Barmax)
Barsweet
Coventry
Indigo
J13-152
Julia
Nustar
Platini
Preakness (602)
PST-B8-106
PST-UD-10
Ram-1
Silvia
SR 2100
Trampas
Unique (PST-C-76)
A-34
BAR VB 1169
BAR VB 7037
Bartitia
Cardiff
Challenger
J-333
NE 80-47
Opal
PST-A7-1877
PST-UD-12
PSU-151
SR 2000
BA 77-292
Banff
Barcelona (BAR VB 1184)
Belmont (798)
Classic
Dawn
Entry 128
Freedom
Georgetown
Haga
HV 125
Liberty
Minstrel
Miranda
PR-1
PST-A84-803

May
6.0
8.0
7.0
7.3
6.7
6.7
7.3
7.0
7.0
6.7
6.0
7.0
7.0
7.0
7.0
7.0
6.7
7.0
7.0
7.7
6.7
6.7
6.0
6.7
7.3
6.3
6.0
6.3
6.0
6.7
7.0
6.3
6.7
6.7
6.7
7.0
6.7
7.0
6.3
7.3
5.7
6.3
6.7
7.0
6.0
7.0
7.0
6.7
6.3
7.0
6.7
5.7
6.3
6.3

June
7.0
7.3
7.0
7.0
7.7
7.3
7.0
8.0
7.3
7.3
7.3
7.0
7.3
7.3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.3
7.0
7.0
7.3
6.7
7.0
7.3
7.0
7.3
7.0
7.0
7.0
7.0
6.3
7.0
7.0
6.7
6.7
7.3
7.0
7.3
6.7
6.7
7.0
7.0
7.0
7.0
7.0
7.0
7.0

July
7.7
7.0
6.7
7.3
7.7
7.7
7.3
7.7
7.3
7.3
7.7
6.7
7.0
7.0
7.0
7.3
7.3
7.7
7.3
7.0
8.0
7.3
7.7
7.3
6.7
7.3
8.0
7.0
7.3
7.7
7.3
7.7
7.3
7.7
7.0
6.7
7.0
7.7
7.7
7.0
7.3
6.7
7.0
6.3
7.0
6.7
6.3
7.0
6.7
6.3
7.0
7.3
7.3
7.0

8

Aug
7.7
7.0
7.0
7.0
7.0
7.3
7.0
7.0
7.3
7.5
8.0
7.0
7.0
7.3
8.0
7.0
7.3
7.3
7.0
7.3
7.5
8.0
7.0
7.0
7.0
7.3
7.0
7.3
7.3
7.0
7.0
7.0
7.0
7.5
7.0
7.0
7.5
7.0
7.0
6.7
7.7
7.0
6.5
7.0
7.3
7.0
7.7
7.0
7.0
7.3
7.3
7.3
7.0
7.3

Sept
7.0
7.0
7.7
7.3
7.5
7.0
7.0
6.7
6.3
7.0
6.7
7.0
7.0
7.0
7.0
7.0
7.0
6.3
6.0
6.7
6.5
7.0
7.3
7.3
7.0
7.0
7.0
7.0
7.7
6.5
6.3
7.0
6.7
6.0
6.7
7.0
7.0
6.7
6.5
6.7
7.0
7.3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.7
6.7
7.0
7.0
6.7

Oct
7.7
7.0
7.7
7.3
7.0
7.3
7.7
6.7
7.3
7.0
7.0
7.7
7.0
7.0
7.0
7.0
7.0
7.3
7.0
7.0
7.0
6.7
7.3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.7
7.7
7.3
7.0
7.3
7.0
6.7
7.3
7.3
7.0
7.0
6.7
7.0
7.0
7.0
7.3
7.0
6.7
7.0
7.0
7.0

Mean
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9

71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124

Cultivar
PST-HV-116
Ronde
Shamrock (H86-712)
BAR VB 895
Cobalt
Crest
Destiny
EVB 13.863
J-335
J-386
Kelly
Livingston
Merit
Nublue (J-229)
Princeton 104
PST-A7-341
PST-A84-405
Suffolk
Trenton
Washington
1757
BA 69-82
BA 73-382
BA 77-700
Barzan
Broadway
Chelsea
Fortuna
Gnome
Jll-94
J34-99
Melba
Monopoly
R751A
Touchdown
Viva (BA 73-366)
4 Aces (PST-RE-88)
BA-78-258
Merion
Nassau
Noblesse
PST-A84-928
PST-R-740
Abbey
Barblue
Baron
Donna
Greenley
KWS PP 13-2
Marquis
Kenblue
Buckingham (BA 74-114)
South Dakota Cert.
Entry 126

May
5.7
6.0
6.7
6.7
7.0
6.3
7.0
6.0
6.3
6.0
6.3
5.3
6.0
7.0
6.0
6.3
6.3
7.0
7.3
6.0
6.7
5.7
6.7
5.7
5.7
6.0
6.0
6.0
6.0
6.3
6.3
5.7
5.7
6.7
5.7
6.0
6.0
5.7
6.7
6.7
5.7
6.3
5.7
5.3
7.3
5.3
5.3
5.7
5.7
5.7
5.0
5.7
5.7
4.3

June
7.0
7.0
6.7
7.0
7.0
7.0
7.0
7.0
6.7
6.7
7.0
7.0
7.0
7.0
6.7
7.0
7.0
7.0
6.7
6.7
6.3
7.0
6.7
6.7
6.3
6.3
6.3
7.0
7.0
7.0
6.7
6.7
6.7
6.7
6.3
7.0
6.3
7.0
6.7
6.7
6.3
6.7
6.7
7.0
6.7
6.3
6.7
6.0
6.7
7.0
5.3
6.0
6.0
5.3

July
7.0
7.7
7.0
6.3
7.0
7.0
6.3
7.0
7.0
7.3
6.7
7.3
7.0
6.7
7.0
7.0
6.7
6.3
6.0
6.7
6.7
6.7
6.7
7.0
7.0
7.3
7.3
6.7
6.7
6.7
7.0
7.3
7.0
6.7
7.3
6.7
7.0
6.7
7.0
6.7
7.0
6.3
7.0
6.7
6.3
7.0
6.7
6.3
6.7
6.0
6.3
6.0
6.3
7.0

9

Aug
7.3
7.5
7.0
7.0
7.0
6.5
7.0
7.3
7.0
7.0
7.0
7.3
7.0
6.5
7.3
7.0
7.0
7.0
7.0
7.3
7.0
7.0
7.0
7.0
7.0
7.5
7.0
7.0
7.0
6.7
7.0
7.5
7.0
7.0
7.0
7.3
7.0
7.0
6.5
6.7
7.0
6.5
7.0
7.0
6.3
7.0
6.3
7.3
6.3
6.7
6.7
6.3
6.5
6.3

Sept
7.3
7.0
7.5
7.0
6.3
7.0
6.3
6.7
7.0
6.7
6.7
7.0
6.7
6.3
7.0
6.7
7.0
6.7
7.0
7.3
7.0
6.5
6.7
7.0
7.0
6.5
6.7
6.5
6.7
6.3
6.5
7.0
6.7
6.5
7.0
6.3
6.7
6.5
6.0
6.3
6.7
6.3
6.5
6.5
5.7
7.0
6.3
7.0
6.5
6.3
7.3
6.0
5.5
6.7

Oct
7.3
7.0
7.0
7.0
6.3
7.0
7.0
6.7
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.7
6.7
6.7
8.0
6.3
7.0
7.0
7.5
6.7
7.0
6.7
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.7
7.0
6.7
6.7
6.7
7.0
6.7
7.0
6.7
7.0
7.0
6.3
6.3
7.0
6.7
6.3
6.3
6.3

Mean
6.9
6.9
6.9
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.6
6.6
6.6
6.6
6.6
6.6
6.6
6.5
6.5
6.4
6.4
6.4
6.4
6.4
6.2
6.1
6.1
6.0

125
126
127
128

Cultivar
Ginger
BA 73-381
BA 76-305
PST-B8-13
LSD(0lo5>

May
5.0
5.3
5.3
4.7
1.3

June
5.3
6.0
6.0
6.3
0.8

July
6.3
5.3
5.7
6.3
1.1

Aug
6.3
6.7
6.5
6.5
1.1

Sept
6.0
6.0
6.5
5.3
1.1

Oct
7.0
5.7
6.0
5.7
1.2

Mean
6.0
5.8
5.8
5.8
0.5

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

Table 2.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

The 1993 quality ratings for the high-maintenance, non-irrigated regional Kentucky bluegrass test.
Cultivar
Aquila
Wabash
A-34
BA 72-500
BA 70-139
Blacksburg
NE 80-50
Sydsport
Mystic
NE 80-88
America
Asset
HV 97
Aspen
Georgetown
Amazon
BA 73-540
NE 80-14
Somerset
Eclipse
Dawn
NE 80-47
NE 80-30
Monopoly
Parade
Ikone
Huntsville
Midnight
NE 80-110
Able I
Glade
F-1872
Trenton
WW AG 491
Tendos
Compact
Conni
BA 72-441
Lofts 1757
Cheri
Julia
NE 80-48

May
6.7
6.7
7.7
6.7
6.3
5.7
7.0
6.7
7.0
6.3
7.0
6.3
5.7
6.7
6.7
6.3
6.7
6.0
6.3
6.3
6.3
6.0
5.7
6.3
6.0
6.3
5.3
5.3
5.7
6.0
5.3
5.3
6.7
6.3
5.7
6.7
5.7
5.7
6.0
6.0
6.0
5.7

June
8.0
8.0
8.3
7.7
6.3
7.7
7.0
6.7
8.0
7.3
7.3
7.0
8.0
6.7
7.0
7.0
7.0
6.7
5.7
6.7
5.7
7.0
7.3
6.7
6.7
7.3
7.7
6.3
8.0
7.0
7.0
6.3
6.7
7.3
7.0
7.0
5.7
6.7
6.0
7.0
7.7
6.7

10

July
9.0
7.7
8.0
8.0
8.0
9.0
6.7
7.0
8.7
8.0
6.3
7.3
7.3
7.7
7.3
7.7
7.3
7.0
7.0
7.3
7.0
7.0
7.7
7.0
6.7
6.3
8.0
8.0
7.7
6.3
7.7
6.3
6.7
7.0
7.3
6.7
7.3
8.0
7.3
7.0
6.7
7.3

Aug
7.3
8.0
6.0
7.7
7.7
7.3
7.7
7.7
6.7
7.7
7.7
7.7
6.7
7.0
7.7
7.3
8.0
7.3
8.0
6.7
7.3
6.3
6.7
5.3
7.3
6.7
6.0
7.3
7.0
7.3
6.7
7.3
6.7
6.3
6.7
6.7
6.3
6.3
6.7
6.7
6.7
6.0

Sept
8.0
7.7
7.0
7.3
7.7
6.7
7.3
7.3
5.0
6.7
8.0
6.7
7.3
7.3
6.3
7.3
6.3
7.3
7.3
7.3
7.7
7.3
6.3
7.7
6.7
6.7
6.7
6.7
6.3
6.7
6.3
7.7
7.0
5.3
6.7
5.7
8.0
6.3
6.3
5.7
6.3
7.0

Oct
7.7
7.7
7.3
7.3
7.3
7.0
7.3
7.3
7.0
6.7
6.3
7.3
7.3
7.0
7.0
6.3
6.0
7.0
6.7
6.7
7.0
7.0
7.3
7.3
7.0
6.7
6.7
6.3
5.7
6.3
6.3
6.7
6.0
7.0
5.7
6.3
6.0
6.0
6.7
6.7
5.7
6.3

Mean
7.8
7.6
7.4
7.4
7.2
7.2
7.2
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.0
7.0
6.9
6.9
6.8
6.8
6.8
6.8
6.8
6.7
6.7
6.7
6.7
6.7
6.7
6.6
6.6
6.6
6.6
6.6
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5

43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

Cultivar
NE 80-55
BA 72-492
Destiny
Kl-152
Welcome
WW AG 495
WW AG 496
Barzan
P-104
RAM I
Merit
BAR VB 534
Cynthia
Merion
Nassau
Haga
BA 70-242
BA 69-82
Rugby
K3-178
PST-CB1
Classic
Joy
BA 73-626
Liberty
Challenger
Park
BAR VB 577
Bristol
Victa
Harmony
WW AG 468
Gnome
Annika
239
Baron
Kenblue
South Dakota Cert.
LSD(0l05)

May
6.3
6.7
6.7
6.3
5.3
6.0
6.0
6.0
5.3
5.3
6.0
6.0
5.3
5.7
6.0
6.7
6.0
5.7
5.7
5.7
5.7
5.7
5.3
6.0
5.7
6.7
5.3
5.3
5.7
5.3
5.3
5.0
5.0
5.3
5.7
5.3
5.0
5.0
1.2

June
6.3
6.7
6.7
6.3
6.7
7.0
7.0
7.0
6.3
6.3
6.0
6.3
6.3
6.3
7.0
6.0
6.0
6.0
6.7
6.0
6.0
5.3
6.0
6.0
5.3
6.3
6.0
6.7
6.0
5.3
6.0
6.0
5.7
6.3
6.3
6.0
6.0
6.0
0.9

July
7.0
6.7
6.7
6.7
7.0
7.3
7.0
6.3
7.0
7.3
7.0
7.3
6.7
7.3
7.3
6.7
6.0
6.0
6.3
6.0
6.7
5.7
7.3
5.7
7.0
6.3
8.0
6.0
6.7
6.3
6.3
6.3
6.3
6.3
6.0
6.3
7.0
7.0
1.5

Aug
7.0
6.0
6.3
6.7
6.3
7.0
6.7
6.3
7.0
6.7
6.0
6.3
6.0
6.0
6.0
6.3
6.3
6.7
5.7
7.3
5.7
6.7
5.7
6.3
6.0
6.0
6.0
6.3
6.0
6.3
5.7
7.3
6.0
6.3
6.0
5.3
5.3
6.0
1.4

Sept
6.0
6.0
6.0
6.7
7.0
5.3
6.3
6.3
5.7
5.7
6.3
5.7
6.3
6.7
5.7
5.7
6.7
7.0
6.7
5.7
6.7
6.0
6.7
6.7
6.3
5.7
6.0
5.3
5.3
6.7
6.3
6.0
6.7
5.7
6.3
6.3
6.0
5.7
1.4

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

11

Oct
6.3
6.3
6.0
6.0
6.0
5.7
5.7
6.0
6.3
6.3
6.3
6.3
7.0
6.0
6.0
6.0
6.3
6.0
6.0
6.7
6.7
7.0
5.7
6.0
6.0
5.3
5.0
6.3
6.3
6.0
6.3
5.3
5.7
5.7
5.3
5.3
5.3
5.3
1.5

Mean
6.5
6.4
6.4
6.4
6.4
6.4
6.4
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.2
6.2
6.2
6.2
6.2
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.0
6.0
6.0
6.0
6.0
5.9
5.9
5.9
5.8
5.8
5.8
0.8

Table 3.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

The 1993 quality ratings for the low-maintenance, non-irrigated Kentucky bluegrass trial.

Cultivar
ISI-21
Alene
BAR VB 7037
BAR VB 852 (Barraax)
Kenblue
Miracle
Monopoly
Barzan
Cynthia
Park
Voyager
Gen-RSP
Banjo (H76-1034)
PST-YQ
Washington
Amazon
BA 78-376
BAR VB 895
Bartitia
Bronco
Freedom
Nublue (J-229)
ZPS-84-749
Barcelona (BAR VB 118)
J-335
Livingston
MN 2405
NJIC
PST-C-303
Sophia
SR 2000
BAR VB 1169
Barsweet
Liberty
Opal
PST-A7-111
RAM-1
South Dakota Cert.
Suffolk
Cobalt
Destiny
Haga
Nustar
PST-C-391
Chelsea
EVB 13.863
J-386
Merit
Midnight
Unique (PST-C-76)
Baron
Belmont (798)

May
7.3
7.3
6.3
6.7
7.3
5.7
6.0
5.7
6.7
7.3
7.3
7.7
7.0
6.7
7.3
6.0
7.3
5.3
5.0
6.7
6.3
6.3
7.7
5.0
6.0
5.7
6.0
7.0
5.3
5.7
5.7
6.3
5.3
6.0
5.3
7.3
5.7
6.0
5.0
5.7
5.0
5.7
5.3
5.3
5.7
5.3
6.0
5.7
6.0
4.7
6.0
5.3

June
7.3
6.3
8.0
7.7
6.0
8.0
7.0
6.3
7.0
6.7
7.0
7.3
6.0
7.3
6.7
7.3
6.0
7.0
7.3
7.0
7.0
6.7
7.0
6.7
6.7
6.3
6.7
6.3
7.3
6.7
6.7
6.3
7.3
6.7
7.0
5.7
6.3
5.3
6.7
6.0
6.7
7.0
6.0
7.0
6.0
6.7
5.3
6.0
6.0
5.7
5.3
5.3

July
6.0
7.0
7.3
6.7
7.0
7.3
6.7
7.0
8.0
7.3
6.3
5.7
5.3
6.3
5.7
5.7
6.7
5.7
7.0
6.7
5.7
6.7
6.7
6.0
5.7
5.7
7.0
6.0
5.7
6.3
5.0
6.3
6.7
6.0
6.7
6.3
6.3
6.0
6.0
6.0
5.7
5.7
5.3
5.3
5.7
5.7
5.3
5.0
5.0
4.7
5.7
4.7

12

Aug
7.7
6.7
6.3
6.7
6.0
5.7
6.3
6.3
6.7
5.7
6.7
6.7
7.3
6.7
6.0
6.7
5.3
6.0
6.3
6.7
6.3
6.7
6.3
6.0
6.3
6.7
6.0
6.0
6.3
6.3
6.7
6.0
6.7
6.0
6.3
5.7
6.7
7.0
6.0
6.3
6.0
6.0
6.0
6.0
6.0
5.7
6.0
6.3
6.7
6.7
5.7
6.0

Sept
7.7
7.3
6.0
5.3
6.7
7.3
6.3
7.0
5.3
6.7
5.7
5.7
6.3
5.0
6.3
6.0
6.7
7.0
6.0
5.3
6.3
5.0
5.0
6.7
6.0
6.3
6.0
5.7
6.3
6.0
6.7
5.7
5.3
5.7
5.3
6.0
5.7
5.7
6.0
5.3
6.0
5.7
6.3
6.0
6.0
5.3
5.7
5.7
5.0
6.7
6.0
6.3

Oct
6.7
6.3
6.3
7.0
7.0
6.0
7.7
7.0
5.7
6.0
6.7
6.0
6.7
6.7
6.3
6.0
5.7
7.0
6.3
5.7
6.0
6.3
5.3
7.0
6.3
6.3
5.7
6.3
6.0
6.0
6.3
6.0
5.0
6.0
5.7
5.7
5.7
6.3
6.3
6.3
6.3
5.3
6.3
6.0
5.7
6.0
6.7
6.0
6.0
6.3
5.7
6.3

Mean
7.1
6.8
6.7
6.7
6.7
6.7
6.7
6.6
6.6
6.6
6.6
6.5
6.4
6.4
6.4
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.2
6.2
6.2
6.2
6.2
6.2
6.2
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.0
5.9
5.9
5.9
5.9
5.9
5.8
5.8
5.8
5.8
5.8
5.8
5.7
5.7

53
54
55
56
57
58
59
60
61
62

Cultivar
Gnome
BA 74-017
Crest
EVN 13.703
KWS PP 13-2
Merion
NE 80-47
Fortuna
Kyosti
Unknown
LSD(ao5)

May
5.7
5.7
5.7
5.3
5.3
5.0
5.0
4.3
4.3
4.7
1.4

June
5.7
6.0
6.0
6.7
5.7
5.7
6.0
5.7
5.3
4.7
1.4

July
5.3
5.0
5.0
5.3
5.0
5.3
5.0
4.7
5.3
4.0
2.0

Aug
6.7
6.3
5.7
5.3
5.7
6.3
6.0
6.3
6.3
5.0
2.8

Sept
5.3
5.7
5.3
5.7
5.7
5.7
6.0
6.0
5.7
5.3
1.5

Oct
5.7
4.7
5.7
5.3
6.0
5.7
5.7
4.7
5.0
4.7
1.7

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

13

Mean
5.7
5.6
5.6
5.6
5.6
5.6
5.6
5.3
5.3
4.7
0.9

The Recovery of Kentucky Bluegrass Cultivars
Following Summer Dormancy N. E. Christians
In earlier work at Iowa State University (Grounds Maintenance 24(8):49-50) it was shown that Kentucky
bluegrass cultivars vary greatly in their recovery from summer dormancy. Common, or public varieties,
generally recover much more rapidly from drought-induced dormancy than do the newer improved
cultivars. The objectives of this study are to further evaluate four cultivars that were previously shown
to recover rapidly from dormancy and four cultivars that were slower to recover when maintained under
low and high fertility regimes: 1 lb N/1000 ft2 in September and 4 lb N/1000 ft2 applied in 1 lb
applications in April, May, August, and September.
South Dakota Common, S-21, Kenblue, and Argyle (cultivars observed to recover rapidly in earlier
studies) and Midnight, Nassau, Glade, and Ram I (cultivars observed to recover more slowly). Kentucky
bluegrass was established in 21 ft2 plots on September 26, 1989 on a non-irrigated site at the turfgrass
research area of the Iowa State University Horticulture Research Station north of Ames, Iowa. The soil
on the site is a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with a pH of 6.8 and 2.3% organic
matter, a P content of 20 lbs/A, and a K content of 216 lbs/A. The study was replicated three times.
Each plot was split in half. The two fertility treatments were randomly applied to the two halves of the
plots.
The 1990 season was very wet and at no time did the grasses on the study area go into summer dormancy.
The spring of 1991 was also very wet and the late summer and fall were dry. The 1992 season was the
opposite of the 1991 season. The spring and summer were very dry up to the 4th o f July. The remainder
of the summer and fall were very wet. The 1993 season was one of the wettest in history. The area
remained saturated through most of the season. At no time was there any moisture stress.
Data were collected in July, August, and September only (Table 4). The improved varieties had
deteriorated in quality during the drier years of 1990, 1991, and 1992. In the wet year of 1993, they
showed considerable recovery and generally matched or exceeded the quality of the common varieties.
This study will be continued for at least one more year.
Table 4. The 1993 quality ratings for the low-moderate maintenance bluegrass study.

1 lb
Cultivar

|

N

4 lb
N

S.D. Common

6.0

7.0

S-21

6.5

7.3

Kenblue
Argyle

i
I

Midnight

4 1b
N

1 lb
N

4 1b
N

6.7

6.0

7.3

7.0

6.0

6.0

7.0

4.7

5.0

5.5

6.6

6.3

6.3

0.0

7.3

7.0

7.5

5.0

6.0

5.3

7.3

3.7

5.6

4.0

4.5

5.3

6.3

6.7

7.3

LSD(ao5)

iI

1 lb
N
5.7

6.3

Nassau
RAM-I

||

6.0

Glade

|

September

August

July

5.7
1.1

i
i

«
1.1

4.5

5.5

6.3

7.7

5.7

7.3

7.0

6.5

5.7

6.0

1.1

1.0

1.0

U

14

1
|

National Perennial Ryegrass Study

-

1993

J. D. Dickson and N. E. Christians

This trial began in the fall of 1990 with the establishment of 125 cultivars of perennial ryegrass at the
Iowa State University Horticulture Research Station. The study was established on an irrigated area
and maintained at a 2-inch mowing height, fertilized with 3 to 4 lb N/1000 fP/yr. The area receives
preemergence herbicide in the spring and broadleaf herbicide in September.
Cultivars were evaluated for turf quality each month of the growing season. Visual quality was based
on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality. The values
listed under each month in Table 5 are the averages of ratings made on three replicated plots for the
three studies. Yearly means of data from each month are listed in the last column. The cultivars are
listed in descending order of average quality.
The winter of 1992-93 resulted in a considerable amount of winter kill in perennial ryegrass and other
species in the midwestem region. The May 1993 ratings reflect winter damage (Table 5). The lowest
ranked cultivars in May were severely damaged by winter conditions. The damaged cultivars showed
near complete recovery by July.

Table 5. The 1993 quality ratings for the national perennial ryegrass study.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

Cultivar
HE 311
Barrage
Loretta
Allegro
Barrage ++
EEG 358
MOM LP 3147
Navajo (PST-2DPR)
Affinity (GEN-90)
CLP 39
Gator
Lowgrow (Pick 89LLG)
PST-20G
Taya
WVPB 89-92
Advent
CLP 144
Cutless
PST-2ROR
APM
Cowboy II (WM-II)
Delaware Dwarf (4DD)
MVF 89-88
Ovation
PST-290
Toronto
Danilo
Elite (WVPB-88-PR-C-23)

May
7.7
7.7
7.3
8.0
6.7
6.3
7.0
7.7
6.7
7.7
7.7
6.7
7.0
7.7
7.0
6.3
7.7
6.7
7.0
7.0
7.0
6.3
6.7
7.0
7.0
7.0
6.7
6.3
15

June
7.7
7.3
7.3
7.3
7.3
7.7
7.7
7.3
7.0
7.3
7.3
8.0
7.3
7.7
7.7
7.7
7.0
7.3
7.0
7.0
7.0
7.0
6.7
7.0
7.0
7.0
7.3
7.0

July
7.7
7.7
7.7
7.3
8.0
8.0
7.7
7.7
7.7
7.0
7.3
7.0
7.7
7.0
7.7
8.0
7.0
7.3
7.3
7.0
7.3
7.7
7.3
7.0
7.3
7.0
7.0
7.0

Aug
7.7
7.7
8.0
7.0
7.7
7.7
7.5
7.3
7.7
7.3
7.3
7.7
7.0
7.7
7.3
7.0
7.3
7.0
7.7
7.3
7.0
7.0
7.3
7.0
6.7
7.7
6.7
7.5

Sept
7.7
7.3
7.3
7.3
7.0
7.7
7.5
7.3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.3
7.0
7.0
7.0
7.3
7.3
7.0
7.3
7.0
7.0
7.3

Oct
7.7
7.3
7.3
7.3
7.7
7.0
7.0
7.0
8.0
7.3
7.0
7.3
7.0
7.0
7.3
7.3
7.3
7.3
7.3
7.3
7.0
7.0
7.3
7.3
7.3
7.0
7.3
7.3

Mean
7.7
7.5
7.5
7.4
7.4
7.4
7.4
7.4
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.2
7.2
7.2
7.2
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.0
7.0

29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

Cultivar

May

June

July

Aug

Sept

Oct

Mean

Fiesta II
PR 9119
C-21
Charger
Dandy
Derby Supreme
Dimension (2H7)
Gettysburg
Manhattan II (E)
Nomad
Pick DKM
Riviera
Unknown
Achiever (Pick 1800)
Cutter (Pick 89-4)
Envy
Lindsay
Prelude II (2P2-90)
Sherwood
Stallion Select (PS-105)
Troubadour
BAR LP 086FL
Essence (PR 8820)
Goalie
Mulligan (NK 89001)
MVF 89-90
N-33
PR 9108
PST-28M
Quickstart (PST-2FQR)
Rodeo II
WVPB-89-87A
Buccaneer (Koos 90-1)
Commander
Evening Shade (Poly-SH)
Koos 90-2
Meteor
Repell
Statesman (WVPB-88-PR-D-12)
Entrar
Pick EEC
Shining Star (PST-2B3)
Calypso
Duet
Legacy
MOM LP 3111
Pebble Beach
Pennfine
Prizm (ZPS-28D)
Saturn
Stallion
Target

6.3
6.0
6.3
6.0
6.0
7.0
5.7
6.7
6.0
6.7
6.7
6.0
6.0
6.0
6.3
6.7
6.0
6.3
6.0
6.7
6.3
6.0
6.7
6.7
6.3
5.3
6.3
6.3
5.7
5.7
6.3
6.3
6.3
5.0
5.7
6.0
5.7
5.7
5.3
6.0
6.0
6.0
5.3
5.0
6.0
5.7
5.7
6.7
5.7
5.7
5.3
5.7

7.0
6.7
7.0
7.3
7.3
6.7
7.3
7.0
7.0
7.3
7.3
7.3
6.7
7.0
6.7
6.7
7.0
7.0
7.0
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
7.0
6.7
6.7
7.0
7.0
6.7
6.7
6.7
6.7
6.7
6.7
7.0
6.3
6.0
6.0
6.7
6.3
6.0
7.0
6.3
6.7
6.3
6.7

7.3
7.3
6.7
6.7
7.3
7.0
7.3
7.0
7.3
6.7
7.3
7.0
7.0
7.0
7.0
6.3
7.0
7.0
7.0
6.7
6.7
7.3
6.7
6.7
7.0
7.3
6.7
7.0
6.7
6.7
6.7
7.0
7.0
6.7
6.7
7.0
7.3
6.7
6.3
7.0
7.0
6.7
6.7
7.0
6.3
6.7
6.7
6.7
6.0
6.7
6.7
6.7

7.3
7.3
7.3
7.0
6.7
6.7
7.0
6.3
6.7
7.0
6.7
6.5
7.0
6.7
6.7
7.0
7.0
7.0
7.0
7.0
7.0
6.3
6.7
7.0
6.7
7.0
7.0
6.7
7.0
7.0
6.0
6.3
6.3
6.7
6.7
6.3
7.0
6.3
7.0
6.0
6.3
6.0
7.0
7.0
6.3
6.5
5.5
6.3
6.7
6.3
6.3
6.0

7.0
7.3
7.0
7.3
7.3
7.0
7.0
7.0
7.0
7.0
6.7
7.0
7.3
7.0
6.7
6.7
7.0
7.0
7.0
6.7
7.0
6.7
6.7
7.0
6.7
7.0
6.0
6.7
7.0
7.0
6.5
6.7
6.7
7.0
6.7
7.0
6.7
7.3
7.0
6.7
7.0
7.0
6.7
7.0
6.3
7.0
7.0
6.0
6.7
6.3
6.7
7.0

7.0
7.3
7.0
7.3
7.0
7.3
7.3
7.3
7.3
7.0
7.0
7.3
7.3
7.0
7.3
7.3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.3
6.7
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.3
7.0
7.0
6.7
6.3
7.0
7.0
6.7
5.7
6.7
7.0
7.0
7.0
7.0
7.0
6.0
7.0
6.7
7.0
6.7

7.0
7.0
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.7
6.6
6.6
6.6
6.6
6.6
6.6
6.6
6.5
6.5
6.5
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4

16

81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125

Cultivar
Yorktown III (LDRF)
Citation II
Danaro
Express
Pleasure
PR 9109
Repel 1 II (LDRD)
Topeka (WVPB-88-PR-D-10)
ZPS-2EZ
Competitor
OFI-D4
PR 9118
PR 9121
SR 4200
Surprise
Equal
MOM LP 3184
Patriot II
Pinnacle
Premier
PST-2FF
Seville
ZW 42-176
89-666
Caliente
Morning Star (SYN-P)
Assure
BAR LP 852
Nighthawk (WVPB-89-PR-A-3)
Palmer II (P89)
Pick 9100
PST-23C
Brightstar (PST-GH-89)
Entry 125
MOM LP 3185
Pennant
Regal
MOM LP 3182
OFI-F7
856
Entry 124
Cartel
MOM LP 3179
Accolade
Linn
LSD(0lO5)

May
5.3
4.7
6.0
5.0
5.0
5.0
5.0
5.3
4.7
4.7
4.7
4.3
4.7
5.3
4.7
5.3
5.3
4.7
4.7
5.0
4.7
4.3
6.0
4.3
4.0
5.0
4.3
5.0
4.3
4.3
4.7
4.7
5.0
4.7
3.7
4.0
5.0
3.7
4.0
3.7
3.7
4.0
3.7
3.3
2.7
1.9

June
6.7
6.7
6.0
6.0
6.3
6.7
7.0
6.3
6.3
5.7
6.7
6.0
6.0
6.3
6.3
6.3
6.0
6.0
6.3
6.0
6.0
6.3
6.7
6.3
6.7
6.0
6.3
6.0
6.3
6.0
6.3
6.0
5.7
5.0
5.7
6.0
6.0
5.3
5.0
5.3
5.3
5.7
5.3
4.3
4.7
1.4

July
7.0
7.0
6.3
6.3
6.3
6.7
6.7
6.7
6.3
6.3
6.3
6.7
6.7
6.0
6.7
5.7
6.3
6.3
6.3
6.3
6.7
6.3
6.3
6.0
6.3
6.0
6.0
6.0
6.3
6.0
5.7
6.0
5.3
6.0
6.0
6.0
5.3
5.7
5.3
6.0
5.3
5.0
5.0
4.7
5.0
1.1

Aug
6.3
6.0
6.0
7.0
6.3
6.0
6.3
6.3
6.3
6.3
6.3
6.7
6.0
6.0
6.3
6.3
6.5
6.0
6.0
6.0
6.0
6.3
5.3
6.0
6.3
6.5
5.7
6.0
6.0
5.7
5.7
6.0
5.7
6.0
6.0
6.0
5.7
5.3
5.3
5.3
5.7
4.3
5.3
4.3
4.7
1.2

Sept
6.7
6.5
6.7
7.0
7.0
6.5
6.3
6.7
7.3
7.0
6.7
6.7
7.0
6.7
6.7
6.7
6.0
6.7
6.0
6.3
6.5
6.7
6.0
6.7
6.3
6.5
6.7
6.3
6.5
6.3
6.3
6.0
6.0
6.7
6.3
5.5
5.7
6.3
6.3
6.3
6.0
6.3
6.3
5.3
5.7
1.0

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

17

Oct
6.7
6.7
6.7
7.0
6.7
6.7
6.3
6.7
6.7
7.0
6.7
6.7
6.7
6.7
6.7
6.3
6.3
6.7
7.0
6.7
7.0
6.7
6.3
6.7
6.3
6.7
6.7
6.3
6.7
6.7
6.3
6.3
6.7
6.0
6.3
6.3
5.7
6.0
6.3
5.3
5.7
5.7
5.7
5.3
4.0
1.0

Mean
6.4
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.2
6.2
6.2
6.2
6.2
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.0
6.0
6.0
5.9
5.9
5.9
5.8
5.8
5.8
5.7
5.7
5.7
5.6
5.6
5.4
5.4
5.3
5.3
5.2
5.2
4.6
4.4
0.9

Regional Fine Fescue Cultivar Evaluation J. D. Dickson and N. E. Christians

This was the final year of data on this trial. It was established in the spring of 1990. The study was
conducted in conjunction with several identical trials across the country, coordinated by the USDA.
The purpose of the trial is to identify regional adaptation of 95 fine fescue cultivars. Cultivais were
evaluated for quality each month of the growing season through October. Visual quality was based on
a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.
Three replications of the 95, 3 ft x 5 ft (15 ft2) plots were established in a 5 ft by 19 ft grid. The
average seeding rates were approximately 55 g per plot or about 8 lb/1000 ft2.
The trial was maintained at a 2-inch mowing height, 3 to 4 lb N/1000 ft2 were applied during the
growing season, and irrigated when needed to prevent drought. Preemergence herbicide was applied
once in the spring. The study was terminated in August of 1993 and was replaced with a new fine
fescue trial sponsored by the USDA.

Table 6. The 1993 quality ratings for the fine fescue regional cultivar trial.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

Cultivar
Bargreen
PST-SHE
LD 3485
89.LKR
PST-43F
Atlanta
Mary
Epsom
Southport
Rainbow
Banner
LD 3488
PST-4FE
Jamestown
Camaro
Molinda
Barcrown
ZW 42-160
SR 5000
PST-4R3
FOT 30149
Jamestown
Herald
OFI 89-200
BAR Fr 9F
JMB-89
Scarlet
HF 112
N-105
Enjoy

May
7.7
7.0
7.3
7.3
7.0
7.7
7.0
7.3
7.0
7.7
6.7
7.3
6.7
6.7
7.0
6.7
8.0
8.0
7.3
6.3
7.0
7.0
7.0
7.3
7.0
7.7
8.0
6.7
6.7
7.7

June
7.7
7.0
7.7
7.3
6.7
7.0
7.0
8.0
7.0
7.7
7.3
7.7
7.0
6.7
7.3
7.0
6.7
7.0
7.0
6.7
6.7
7.0
7.0
7.3
7.0
7.7
7.0
7.3
7.3
7.0
18

July
7.3
7.7
7.3
7.3
8.0
7.0
7.3
6.7
7.3
6.7
7.3
7.7
7.3
7.3
7.0
7.3
7.3
7.0
7.3
7.7
7.0
7.0
7.0
6.7
6.7
6.0
6.3
7.0
7.7
6.7

Aug
7.0
8.0
7.3
7.7
7.7
7.3
7.7
7.0
7.7
7.0
7.7
6.7
7.7
8.0
7.0
7.3
6.3
6.3
6.7
7.7
7.7
7.3
7.3
7.0
7.3
6.7
6.7
7.0
6.3
6.7

Mean
7.4
7.4
7.4
7.4
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.2
7.2
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.0
7.0
7.0
7.0
7.0
7.0

31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84

Cultivar
Wilma
NK 82492
PST-4CD
HF138
Cindy
Longfellow
ERG 1143
Attila
BAR Fr 9F
Barlotte
Barnica
SR 3000
PST-4HD
PST-4C8
Shadow
Dawson
Raymond
Capital
Marker
Jasper
Puma
SRX 89-31
PST-4NI
Vista
WW Rs 143
BARB 09A2
Belvedere
HF 102
LD 3438
Warwick
Shademaster
Silvana
Koket
Reliant w/Endophyte
NK88001
Estoril
Claudia
LD 3414
Franklin
Melody
WW Rs 130
WW Rs 138
Scaldis
ZW 42-148
PST-4AG
Aurora
PST-AUE
Flyer
Reliant w/o Endophyte
Waldorf
Bargena
Salem
Boreal
Ensylva

May
7.3
7.0
6.3
6.7
6.7
7.3
6.7
7.0
7.0
7.3
6.7
7.7
8.0
6.3
6.7
6.7
7.0
7.3
6.7
6.3
7.0
8.0
6.3
6.7
6.0
7.3
6.0
5.7
6.7
7.3
6.0
7.7
6.0
7.0
5.7
6.7
5.0
6.0
5.3
7.7
6.0
6.0
7.0
5.7
7.3
7.3
7.3
5.7
7.3
7.3
5.3
6.0
5.3
4.7

June
7.3
6.7
7.0
7.0
7.3
7.0
7.0
7.0
7.0
7.3
6.7
7.3
7.0
6.7
6.3
7.3
7.0
7.0
6.7
6.7
7.0
7.3
6.7
6.7
7.3
6.3
6.0
6.3
6.7
6.7
6.7
6.7
6.3
7.0
6.3
6.3
6.0
6.3
6.0
6.3
6.7
6.7
7.0
6.0
7.0
7.0
6.7
6.0
7.3
6.0
6.0
6.3
6.0
5.7

19

July
6.7
7.3
7.0
7.0
6.3
6.7
7.0
6.7
7.0
6.3
6.7
6.7
6.3
7.0
7.0
7.0
6.3
6.3
7.0
6.7
6.3
6.3
7.0
6.7
6.3
6.7
7.0
7.3
6.7
6.7
6.7
6.0
7.0
6.3
6.3
6.0
7.0
6.3
6.7
6.0
6.0
6.3
6.0
6.7
6.3
6.0
6.0
6.7
6.0
6.0
7.0
6.3
6.3
7.3

Aug
6.7
6.7
7.3
7.0
7.3
6.7
7.0
6.3
6.3
6.0
7.3
5.7
5.7
7.0
7.3
6.3
6.7
6.3
6.7
7.3
6.7
5.0
6.7
6.7
6.7
6.0
7.3
7.0
6.3
5.7
6.7
5.5
6.7
5.3
7.3
6.7
7.7
7.0
7.0
5.0
6.3
6.3
5.0
7.0
4.7
4.7
5.0
6.7
4.7
6.0
7.0
6.3
7.3
7.0

Mean
7.0
6.9
6.9
6.9
6.9
6.9
6.9
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.7
6.7
6.7
6.6
6.6
6.6
6.6
6.6
6.6
6.5
6.5
6.5
6.4
6.4
6.4
6.4
6.4
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.2

85
86
87
88
89
90
91
92
93
94
95

Cultivar
Valda
Eureka
Serra
Biljart
Crystal
Bighorn
BAR Fr8RC3
Sylvester
Elanor
Barreppe
Mx-86
LSD(ao5)

May
7.0
7.0
7.3
8.0
7.0
6.7
5.0
4.7
5.3
5.0
4.3
1.2

June
6.7
7.0
6.7
4.7
6.3
5.7
6.0
5.7
5.3
5.0
4.3
1.1

July
6.0
5.3
5.3
6.3
6.3
6.0
6.3
6.3
5.3
5.7
5.0
1.2

Aug
4.7
5.0
4.7
5.0
4.3
5.3
6.3
6.3
6.3
6.7
4.0
1.3

Mean
6.1
6.1
6.0
6.0
6.0
5.9
5.9
5.8
5.6
5.6
4.4
3.8

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

20

Shade Adaptation Study

-

N. E. Christians

The shade adaptation study was established in the fall of 1987 to evaluate the performance of 35 species
and cultivais of grasses. The species include creeping red fescue (C.R.F.), hard fescue (H.F.), tall fescue
(T.F.), Kentucky bluegrass (K.B.), and rough bluegrass (
trivialis).
The area is located under the canopies of a mature stand of Siberian elm trees (Ulmus
) at the
Iowa State University Horticulture Research Station north of Ames, Iowa. The grasses were mowed at
a 2-inch height and received 2 lb N/1000 ft2/year. No weed control has been required on the area. The
area was irrigated during extended droughts.
Monthly quality data were collected from May through October (Table 7). Visual quality was based on
a scale o f 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality. This trial has been
observed through the extremes of the drought year 1988 and the very wet conditions of 1993. The
quality of the various species included in this trial vary greatly with moisture conditions. In dry
weather, the fine fescues, especially the hard fescues, do well, whereas Rough bluegrass (
trivialis)
deteriorates badly. In extended wet periods, Rough bluegrass does very well. Some of the tall fescues
and chewings fescues also tend to perform better in wet conditions.

Table 7. The 1993 quality ratings for grasses in the shade trial.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

Cultivar

May

June

July

Aug

Sept

Oct

Mean

Sabre (Poa trivialis)
Victor (C.F.)
Rebel (T.F.)
Mary (C.F.)
Arid (T.F.)
Shadow (C.F.)
Estica (C.R.F.)
Jamestown (C.F.)
Falcon (T.F.)
Midnight (K.B.)
Pennlawn (C.R.F.)
Apache (T.F.)
Bonanza (T.F.)
Rebel II (T.F.)
Banner (C.F.)
Coventry (K.B.)
Ensylva (C.R.F.)
Waldorf (C.F.)
RAM I (K.B.)
Atlanta (C.F.)
ST-2 (SR 3000) (H.F.)
Waldina (H.F.)
BAR FO 81-225 (H.F.)
Agram (C.F.)
Glade (K.B.)

3.3
6.3
5.3
7.7
5.3
7.0
4.7
6.3
5.7
4.7
7.7
4.3
4.0
4.7
7.0
5.0
5.3
5.0
5.0
5.7
6.0
5.3
6.7
5.0
4.3

8.3
6.3
7.0
5.7
6.7
6.0
6.0
5.7
6.0
6.7
6.3
7.0
7.0
5.7
6.0
6.0
5.7
6.7
5.7
6.3
5.7
5.0
5.7
5.3
6.0

8.0
7.3
7.3
7.0
6.3
6.0
6.7
6.7
6.7
7.0
7.7
7.0
6.7
6.3
6.0
6.3
6.3
7.7
6.0
6.3
7.0
5.7
7.3
5.7
5.7

7.3
7.3
6.7
5.3
6.3
6.0
6.7
6.3
6.7
6.7
4.3
6.0
6.3
6.3
4.7
6.3
5.3
4.3
5.7
4.7
4.3
4.7
33
4.7
5.0

8.7
7.7
7.0
6.7
7.7
7.0
7.7
6.0
6.7
7.0
4.7
6.3
7.0
6.3
5.3
5.7
6.0
5.0
6.7
5.3
5.0
5.3
4.3
5.3
5.0

8.7
8.0
8.3
7.7
7.7
7.7
7.7
8.0
7.3
6.3
7.0
7.3
7.0
7.3
7.0
6.7
6.7
7.0
6.7
6.3
6.0
7.0
5.7
6.7
5.7

7.4
7.2
6.9
6.7
6.7
6.6
6.6
6.5
6.5
6.4
6.3
6.3
6.3
6.1
6.0
6.0
5.9
5.9
5.9
5.8
5.7
5.5
5.5
5.4
5.3

21

26
27
28
29
30
31
32
33
34
35

Cultivar

May

June

July

Aug

Sept

Oct

Mean

Koket (C.F.)
Chateau (K.B.)
Biljart (H.F.)
Highlight (C.F.)
Wintergreen (C.F.)
Bristol (K.B.)
Spartan (H.F.)
Scaldis (H.F.)
Nassau (K.B.)
Reliant (H.F.)
LSD(0.05)

6.3
5.3
5.7
5.3
5.3
4.0
4.3
5.3
3.7
4.3
2.0

4.7
5.3
5.7
5.7
5.7
5.0
5.0
5.3
4.3
4.7
1.4

5.3
5.7
6.0
6.0
7.0
5.0
5.3
6.0
5.3
5.0
1.3

4.0
4.0
3.3
3.7
3.3
4.3
3.0
3.0
3.0
2.7
2.3

4.3
5.0
4.3
4.3
3.7
5.0
4.0
3.3
3.7
3.7
2.6

6.3
6.0
5.0
5.0
5.0
6.7
6.7
4.3
5.7
5.0
2.3

5.2
5.2
5.0
5.0
5.0
5.0
4.7
4.6
4.3
4.2
1.5

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and
1 = poorest quality

22

USGA Buffalograss Trial -1993
N. E. Christians

The USGA buffalograss trial consists of 5 buffalograss (Buchloe dactyloides) varieties developed as
part of the USGA turfgrass breeding program that are being compared to a standard buffalograss
variety ’Texoka’.
The trial was established in August, 1988, and suffered considerable winter kill because of the late
planting date. Only variety 84-315 survived the first winter in a satisfactory condition. In November
1989, plugs o f all varieties were established in the greenhouse and maintained during the winter of
1989-1990. All six field plots were reestablished in the last week of May, 1990. The summer of
1990 was very wet. These plugs became well established during the growing season and all reached
100% cover by dormancy in September, 1990.
The first quality ratings were taken in 1991 and the data included in this report is from the third full
season of data collection (Table 8). Visual quality was based on a scale of 9 to 1: 9 = best quality, 6
= acceptable quality, and 1 = poorest quality. In 1993, 84-315 was the highest rated variety. Varieties
84-409 and 84-304 were severely damaged during the winter. Very little of the grass on these plots
survived the 1993 season. Data collection will continue for several more seasons on these grasses.

Table 8. The 1993 quality ratings for the USGA buffalograss study.

Cultivar

June

July

Aug

Sept

Mean

1

84-315

7.7

8.0

7.3

7.7

7.7

2

Texoka

7.7

7.3

7.7

7.3

7.5

3

85-378

6.0

6.7

5.7

7.0

6.3

4

84-609

3.0

4.0

4.3

5.0

4.1

5

84-409

1.0

1.0

1.7

3.0

1.7

6

84-304

1.3

1.3

1.3

1.7

1.4

LSD(o.o5)

1.8

2.0

2.4

1.9

1.7

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and
1 = poorest quality

23

Alkaligrass Evaluations -1993
N. E. Christians

Alkaligrass (Puccinellia spp.) is a grass that is well adapted to soils that are high in sodium (Na+). There
are many regions in the country, particularly in the west where levels of Na+ are so high that Kentucky
bluegrass, ryegrass, and other cool season grasses cannot survive. In these regions, alkaligrass is a
reasonable substitute. In Iowa, there are few areas where Na+ levels are naturally high, but Na+ can readily
be elevated to toxic levels along city streets and other road areas where salt is applied for ice melting
purposes in the winter and alkaligrass is used in the state in those areas.
The United States Golf Association has been supporting research at Colorado State University for several
years on the selection and development of alkaligrass for use on golf courses. Four of these varieties are
presently being compared to an industry standard (Fultz weeping Alkaligrass) at the Iowa State University
Turfgrass research area since 1991. The results of the 1993 test are in Table 9.
There were no significant differences among any of the varieties in 1992 and all of them generally
maintained an unacceptable quality rating through the season. They showed some improvement during
the spring of 1993, but then badly deteriorated in the very wet summer conditions. Nearly all o f the
alkaligrass had died by September, 1993. No significant differences we found among the treatments in
any of the months that evaluations were taken.

Table 9. The 1993 quality ratings for the alkaligrass, non-inigated study.

Cultivar

May

June

July

Aug

Mean

1

Fultz

4.7

3.7

3.0

2.7

3.5

2

#2

4.7

3.3

3.7

3.0

3.7

3

#14

5.3

3.7

3.7

3.7

4.1

4

#18

5.7

4.6

4.0

2.7

4.1

5

#57

5.0

3.3

3.7

2.6

3.9

LSD(0.05)

NS

NS

NS

NS

NS

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality

24

Green Height Bentgrass Cultivar Trial (Native Soil)
N. E. Christians and R. W. Moore

This is the third year of data for the 20 cultivars that were established in the fall o f 1989 at the Iowa
State University Horticulture Research Station. The study was reseeded in the spring of 1990 because
of poor winter survival.
The cultivars are maintained with a fertilizer program of 1/4 lb N applied at 14-day intervals with an
approximate total of 6 lbs of N/1000 fF/growing season. A 3/16-in mowing height was used.
Fungicides were used as needed in a preventative program. Herbicides and insecticides were applied
only in a curative program.
Table 10 contains the averages of monthly visual quality ratings. Visual quality was based on a scale
of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality. The ranking of cultivars
was quite different in the very wet conditions of 1993 than in earlier years, although the standard
varieties like Emerald, Penncross, and Pennlinks still performed well through the season. The two top
ranked varieties were Lopez and Regent. Providence and National were the lowest ranked varieties in
1993.
Table 10. The 1993 ratings for the green height bentgrass trial.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

Cultivar

May

June

July

Aug

Mean

Lopez (WVPB 89-D-15)
Regent (Normarc 101)
Emerald
Penncross
Pennlinks
Pro/Cup (Forbes 89-12)
Putter
Bardot
Carmen
BR 15183
Tracenta1
Entry 20 (Southshore)
SR 1020
Cobra
88.CBE
Allure
Egmont2
88.CBL
Providence
National
l s d (005)

6.3
5.3
5.0
6.0
6.3
5.0
4.0
5.7
4.3
53
4.3
5.0
5.7
5.0
4.7
6.3
5.3
4.7
5.0
5.3
NS

8.3
7.0
7.0
6.7
6.3
6.7
7.0
7.0
6.3
6.3
6.7
6.7
5.3
5.7
5.3
5.0
5.0
5.3
5.0
4.3
5.6

9.0
7.7
7.3
7.3
6.7
7.0
7.7
6.7
7.7
6.7
6.7
6.3
6.3
6.7
5.7
5.0
5.3
5.7
5.3
4.0
5.3

8.3
6.7
7.0
6.3
7.0
7.0
7.0
6.0
7.0
6.3
6.7
5.3
5.7
4.3
5.3
5.0
5.3
4.7
5.0
4.7
6.0

8.0
6.7
6.6
6.6
6.6
6.4
6.4
6.3
6.3
6.2
6.1
5.8
5.8
5.4
5.3
5.3
5.3
5.1
5.1
4.6
3.7

‘Tracenta and Allure are colonia bentgrasses, A grostis tenuis.
2Egmont is a browntop bentgrass, A grostis capillaris.
3BR 1518 is a dryland bentgrass, A grostis castollana.
Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.
25

Fairway Height Bentgrass Study -1993
N. E. Christians and R. W. Moore

The fairway height bentgrass study was established in the fall of 1988 to compare the response of several
new cultivais of seeded bentgrasses with the older types. The grass was kept at a 0.5-in mowing height,
the standard mowing height for creeping bentgrass fairways. The area received liquid applications of urea
as needed during the season (0.2 lb N/1000 ft2/application in 3 gal water/1000 ft2). The total N application
rate was approximately 3 lbs/season. Fungicides and insecticides were used as needed. The area was
irrigated as needed.
Table 11 contains monthly visual quality ratings. Visual quality is based on a scale of 9 to 1: 9 = best
quality, 6 = acceptable quality, and 1 = poorest quality. The area was saturated through most of May,
June, and July and no significant differences were observed among varieties in those months. By August,
statistically significant differences were apparent. Providence (SR 1019) was the highest rated variety in
1993.

Table 11. The 1993 quality ratings for the fairway height bentgrass study.

Cultivar

May

June

July

Aug

Mean

1

Providence (SR 1019)

6.3

7.0

8.0

8.7

7.5

2

ISI 123

6.3

7.7

7.3

7.3

7.2

3

Pennlinks

6.3

7.3

7.3

7.7

7.2

4

Putter

6.3

7.0

7.3

8.0

7.2

5

ISI 124

6.3

7.0

7.3

7.7

7.1

6

Penneagle

7.0

7.3

7.0

7.0

7.1

7

Penncross

6.3

7.0

6.7

8.0

7.0

8

J.H. Bent

5.7

7.3

7.3

7.3

6.9

9

SR 1020

6.3

7.0

7.0

7.3

6.9

10

Emerald

6.0

7.0

7.7

6.3

6.8

11

Southshore

5.7

7.3

7.3

7.0

6.8

12

Cobra

6.0

6.3

7.3

6.7

6.6

13

Exeter (Colonial Bent)

6.0

6.3

5.7

7.0

6.3

14

Carmen

5.7

6.0

6.7

6.0

6.1

15

National

5.3

5.7

6.7

6.7

6.1

16

Prominent

5.0

5.7

6.0

5.7

5.6

LSD(00,)

NS

NS

NS

1.5

1.1

Quality based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

26

Herbicide and
Growth Regulator
Studies

1993 Preemergence Annual Weed Control Study
N. E. Christians and R. G. Roe

The 1993 preemergence annual weed control study was conducted at the turfgrass research area on a
Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) soil with a pH of 6.2, 2.3% organic matter, 19 ppm
P, and 96 ppm K. The objectives of the project were to evaluate the efficacy of several labeled and
experimental preemergence herbicides applied to a Ram 1 Kentucky bluegrass turf for the control of
crabgrass. Plots measured 5 ft by 5 ft. They were arranged in a randomized, complete-block design with
three replications.
The area was seeded in the fall of 1991 with a combination of large hairy and smooth crabgrass that had
been harvested from the research area. Treatments were applied on April 28. Liquids were applied with
a backpack carbon dioxide sprayer equipped with 8006 nozzles in the equivalent of 3 gal water/1000 ft2.
Granular materials were applied with a hand-held shaker. The summer of 1993 was the wettest in history
for the region (Figure 1). The soil on the area was saturated through most of the test period. Surprisingly,
excess water did not result in more weed infestation. The bluegrass was very competitive with annual
weeds. Much of this competitiveness was due to the inability to mow the area on a regular basis because
o f the very wet conditions. The cool weather of midsummer also favored the cool season bluegrass over
the competing warm season weeds.
The study was observed weekly for signs of phytotoxicity throughout the season. No damage was
observed on any of the treated plots at any time during the summer of 1993. Estimates of the percentage
cover o f crabgrass were made on 8/20/93. Total lack of moisture stress made data collection difficult.
By September, crabgrass had all but disappeared from the plot area. All treatments significantly reduced
crabgrass. Several treatments provided 100% crabgrass control (Table 12). The Andersons and HoJo
(Howard Johnson) materials were fertilizers loaded with different amounts of Dimension. These materials
were very effective at the 0.188 lb ai rate. Barricade, Dimension 1 EL, and some o f the experimentals
from Rhone Poulenc (Exp) also provided 100% crabgrass control.

27

4 / 7 4 / 1 4 4 /2 1 4 / 2 8 5 / 5 5 / 1 2 5 / 1 9 5 / 2 6 6 / 2

Figure 1. 1993 Weather Data

6 / 9 6 / 1 6 6 / 2 3 6 / 3 0 7 / 7 7 / 1 4 7/21 7 / 2 8 8 / 4 8/1 1 8 / 1 8 8 / 2 5 _ 9 / l _ 9 / 8 J 3 / ^ ^

(s8Ljou¡) iiejurey eAjieiniuno

(j) ejn;Bjeduiei

28

mo-] ç

qßiH A|>|©0m

Table 12. Percentage cover of crabrass on Kentucky bluegrass plots.

lbs a.i./A

Crabgrass
% Cover

1. Control

—

14

2. Pendimethalin 60WP

1.5

1

3. Pendimethalin 60WP

3.0

1

4. Barricade 65WG

0.33

0

5. Barricade 65WG

0.5

0

6. Barricade 65WG

0.65

0

Product

7. Dacthal 75WG

10.0

2

8. 022094 50WG

1.5

4

9. 022094 50WG

3.0

5

10. Exp 30742B 2.3G

5.0

1

11. Exp 30742B 2.3G

6.0

0

12. Exp 31068A 5G

5.0

0

13. Exp 31068A 5G

6.0

1

14. Exp 30911A 5G

5.0

0

15. Chipco Ronstar G. Bio 2G

3.0

1

16. Dimension 1EL

0.375

0

17. Anderson 65105

0.063

2

18. Anderson 65105

0.125

2

19. Anderson 65105

0.188

0

20. HoJo 651XX

0.063

0

21. HoJo 65135

0.125

2

22. HoJo 65135

0.188

0

23. O.M. Scotts 30-3-10
w/Pendimethalin 1.15%

1.5

1

24. O.M. Scotts 30-3-10
w/Pendimethalin 1.15%

1.8

2
4

LS^O.05

29

1993 Postemergence and Preemergence Annual Grass Control Study
N. E. Christians and R. G. Roe

The objective o f this study was to investigate the effectiveness of several postemergence and preemergence
annual grass herbicides for the control of crabgrass. The work was conducted on a Nicollet (fine-loamy,
mixed, mesic Aquic Hapludoll) soil with a pH of 6.1, 3.3% organic matter, 20 ppm P, and 96 ppm K.
Individual plots measured 5 ft by 5 ft. The grass on the area was Indigo Kentucky bluegrass. The
treatments were arranged in a randomized, complete-block design with three replications. The summer
of 1993 was the wettest in history for the region (Figure 1 Page 28). The soil on the area was saturated
through most o f the test period. Surprisingly, excess water did not result in more weed infestation. The
bluegrass was very competitive with annual weeds. Much of this competitiveness was due to the inability
to mow the area on a regular basis because of the very wet conditions. The cool weather o f midsummer
also favored the cool season bluegrass over the competing warm season weeds.
The study area was seeded in the fall of 1991, with a combination of large hairy and smooth crabgrass
that had been harvested at the research area. Treatments 2, 3, and 8 were applied preemergently on
5/12/93. Treatments 4, 5, 6, 7, 9, and 10 were applied on 6/11/93 when the crabgrass was in the 1 to 2
leaf stage. All treatments were applied with a backpack carbon dioxide sprayer equipped with 8006
nozzles. The spray pressure was 20-25 psi. Treatments were applied with the equivalent o f 3 gal
water/1000 ft2.
The plots were observed weekly for signs for phytotoxicity. No damage was observed on any o f the plots
during the season. This may have partly been due to the very wet and cool conditions. Estimates of
percentage crabgrass cover were made on 8/20/93 (Table 13). The preemergence applications were very
effective. The postemergence applications with Dimension were surprising ineffective. This material has
proven to be a very effective postemergence material in past studies at this location. The reason for this
ineffectiveness this years is uncertain, although it was likely related in some way to the unusual weather
conditions.
Table 13. Percentage cover of crabrass on Kentucky bluegrass plots.
Product
1. Control

Crabgrass
% Cover

lbs a.i./A

37

—

2. Pre-M 60WP

3.0

Pre*

3

3. Barricade 65WG

0.75

Pre

1

4. Acclaim 1EC + Pre-M

0.8 + 2.0

E Post

2

5. Acclaim 1EC + Pre-M

0.125 + 2.0

E Post

8

6. Acclaim 1EC + Barricade

0.08 + 0.75

E Post

2

7. Acclaim 1EC + Barricade

0.125 + 0.75

E Post

1

8. Dimension 1EL

0.50

Pre

4

9. Dimension 1EL

0.375

E Post

40

10. Dimension 1EL

0.50

E Post

19
24

LSD q.05

30

Broadleaf Weed Control Study - 1993
N. E. Christians and R. G. Roe
The objective o f this study was to investigate the efficacy of several herbicides as postemergence
controls o f broadleaf weeds in turf areas. The study was conducted at the Iowa State University
Horticulture Research Station north of Ames, Iowa. The soil on the site was a Nicollet (fine-loamy,
mixed, mesic Aquic Hapludoll) with an organic matter content of 3.0%, a pH of 7.25, 10 ppm P, and
105 ppm K. Individual plots measured 5 ft by 10 ft. They were arranged in a randomized, completeblock design with three replications. The area was irrigated as needed to prevent dormancy o f the
Kentucky bluegrass turf. The grass on the area is a common Kentucky bluegrass established in 1968.
This site had a good population of dandelion (
Taraxacumofficianale), white clover
and Black M edic (Medicago sativa) (Table 14). Treatments were applied on June 15, 1993, at 8:00
a.m. Conditions were nearly ideal for weed control. No rain occurred until June 16, more than 24
hours after treatment. All treatments were applied with a backpack carbon dioxide sprayer equipped
with 8006 nozzles. The spray pressure was 20-25 psi. Treatments were applied with the equivalent o f
3 gal water/1000 ft2.
No phytotoxicity on the Kentucky bluegrass was observed. Weed counts and estimations of
percentage weed cover were made on August 3, 1993 (Table 14) when maximum control was achieved
and before germination o f a new weed crop occurred on the area. Normally, later dates o f data
collection would have been included, but due to extremely wet weather conditions (Figure 1 Page 28),
germination o f weeds occurred in mid August and data would not have reflected weed control by the
herbicides. All treatments significantly reduced weeds on August 3. There was a considerable
difference in clover control among treatments. Trimec and Confront (in both the liquid and granular
forms) provided excellent control as did some of the experimental materials. There was a very high
population o f dandelions. None of the products provided 100% control of this species. Trimec and
liquid Confront provided the best dandelion control. Black Medic was less widely distributed in the
test area. Most materials provided good control of this species.
Table 14. Weed count on broadleaf weed control trial - June 15, 1993
Treatment
1
2

Control
Exp 31044A 3.25 SL

Rate
(lb ai/A)
—
1.73

Clover
% Cover

# of
Dandelion

# of
Black Medic

65

213

10

2

16

0
0

3

Trimec 4.25 EC

2.13

1

12

4

Chipco Weedone Amine 3.7 SL

1.85

30

32

2

5

Confront XRM 5085 3 SL

0.75

0

9

0

6

Turflon ester XRM
4714 4 EC
+ 2,4-D ester

0.5
1.0

4

15

0

7

Confront/Fert NAF 0.47%

0.75

8

Scotts TB + 2 2.34%

3.0

1
18

30
57

1
1

9

S-4278 32-3-4

0.5

2

33

0
0
0

10

S-4278 32-3-4

0.75

1

27

11

S-4281 Biodac

0.5

18

43

12

S-4281 Biodac

0.75

7

40

0

S-4281 Biodac

1.0

0

36

0

21

27

5

13

LSDao5

31

The Effects of High and Low Nitrogen Regimes on
the Response of Creeping Bentgrass and Kentucky Bluegrass
to Growth Regulating Compounds
N. E. Christians

The response o f turfgrasses to growth regulating compounds are known to vary with differing
environmental conditions and with a variety of other external factors. In this study, the effects o f high
and low nitrogen (N) regimes were studied on the response of creeping bentgrass and Kentucky
bluegrass maintained under fairway conditions to Primo (Trinexapac-ethyl) and Cutless (Flurprimodol).
The study was conducted during the 1993 season at the Iowa State University Horticulture Research
Station north of Ames, Iowa. The creeping bentgrass area was initiated on a 14 year old stand o f
Penncross creeping bentgrass maintained at fairway mowing height (0.5 inches). The area had
received 0.5 lbs N/1000 ft2 in the early spring before the study was established. The site is watered as
needed to prevent stress, but due to very heavy rainfall in 1993, irrigation was not necessary through
most of the study period. The soil on which the turf was established was a modified soil mix
consisting of 5% gravel, 62% sand, 21% silt and 12% clay with 1.7% organic matter. The pH o f this
soil is 7.9, with P levels of 9 ppm, and K levels of 128 ppm. The Kentucky bluegrass was established
on a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) soil with a pH of 7.75, P level of 20 ppm,
K level o f 114 ppm and an organic matter content of 3.4%. The cultivar was Midnight and the area
was established in 1985. It was maintained at a 1 inch mowing height.
Both the creeping bentgrass and Kentucky bluegrass trials were conducted in split plot designs with 3
replications. The main plots were two nitrogen regimes: 0.5 and 1.0 lb N/1000 ft2 per month. The N
source was urea, which was applied in the liquid form with a backpack sprayer in the equivalent o f
3 gal water/1000 ft2. The first applications o f N were made 2 weeks before growth regulator
treatments were established. Follow-up treatments were made at 30 day intervals throughout the study
period.
The growth regulator treatments were applied as subplots within the two N regime main plots. There
were 3 growth regulator treatments in the creeping bentgrass study, including a control, Primo at 0.09
lb a.i./acre (0.75 pints/acre), and Cutless 50 WP at 2.19 lb a.i./acre (1120 g a.i./ha). There were 4
growth regulator treatments in the Kentucky bluegrass study, including a control, Primo at 0.09 lb
a.i./acre (0.75 pints/acre), and 0.18 lb a.i./acre (1.5 pints/acre), and Cutless at 2.19 lb a.i./acre
(1120 g a.i./ha). The treatments were applied as liquids in the equivalent o f 3 gal water/1000 ft2 with
a backpack sprayer equipped with 8006 nozzles at 20 psi. The individual growth regulator plots
measure 5 ft X 5 ft. The treatments were initiated on 6/11/93 with a follow-up treatment at the same
rate on 7/16/93.
The N content of the tissue was determined at 5 intervals during the study (Table 15). Clippings were
collected separately in each of the 3 replications of the 0.5 and 1.0 lb N a.i./1000 ft2 treatments and
submitted to the Ohio Agricultural Research Development Center nutrient tissue testing laboratory for
N determination. The data presented in Table 15 are the means of the 3 replications.
The summer o f 1993 was the wettest in recorded history with more than 40 inches o f rain recorded
during the test period (Figure 1 Page 28). The plot area was saturated through much o f this time.
Quality data were also collected on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and
1 = poorest quality. Clippings were collected from the 5 ft X 5 ft plots on 2 dates following each o f
the 2 applications. Clippings were ovendried at 75°C for 48 hours and data were reported as average
32

dry weight o f clippings for the 3 replications. Initially, additional dates of clipping collection were
planned, however, the difficulty of collecting clippings at the low mowing height maintained in the
studies, when the soil surface was wet, limited clipping collection.
The tissue N content o f the grass in the high N treated plots was consistently 0.2 to 0.3% higher than
the N level in the grass maintained under the low N regime for the Kentucky bluegrass study. The
only exception was the third clipping date which occurred on 8/3 after a very wet period and shortly
before N retreatment (Table 15). The grass in the high N plots in the bentgrass area were 0.2 to 0.6%
greater than the grass in the low N plots.
An analysis o f variance was conducted on the data (Table 16). Of greatest interest is the treatment by
nitrogen rate interaction (TMT*N), which tests the hypotheses that the response to the growth
regulator treatments varied with nitrogen rate. A significant TMT*N interaction was observed on 6/24
and 8/17 only for quality response of the Kentucky bluegrass. Nitrogen rate affected clipping
treatment response on 7/16 and 8/17. No TMT*N interactions were observed at any of the quality
rating dates or at any of the clipping collection dates in the creeping bentgrass study.
The interaction between the growth regulator treatment and the nitrogen level on Kentucky bluegrass
at the 6/24 rating date was due to a reduction of discoloration of plots treated with both Primo and
Cutless at the 1.0 lb N rate (Table 17). This same trend was observed on some of the later rating
dates as well, but was statistically significant on the 8/17 date only. Although there were some small
reductions in discoloration of bentgrass at the higher N level, at no time was there a significant
interaction o f N and growth regulator treatment. The lack of an interaction was partly due to less
discoloration o f bentgrass than Kentucky bluegrass at both N rates.
Clipping weights varied greatly from testing date to testing date due to the extremely wet conditions.
Because of the low mowing height, there was a need to harvest clippings with a reel mower which
requires a relatively dry soil surface. The area was saturated through most of July and early August
which made clipping collection difficult. The very high clipping levels recorded on 8/3 on the
Kentucky bluegrass area was due to the inability to mow the site for several days before clipping
collection and to an unusually low mowing height setting on the mower. Qipping weights should be
compared among growth regulator treatments and N levels within a collection date only.
The Primo and Cutless were effective at reducing tissue production even though the area was very wet
during the study period. This was particularly true for the creeping bentgrass. The significant
TMT*N interactions observed on 7/16 on the bluegrass area appears to be due to a greater reduction
on growth relative to the control at the lower N rate. There is evidently less growth reduction at the
higher N rate (Table 16 and Table 19). On 8/17, a similar trend occurs for the Primo, but not for the
Cutless. The growth reduction for the Cutless was relatively greater at the higher N level. There were
no TMT*N interactions observed on the bentgrass area (Table 16).
It is not possible to draw final conclusions from data collected in such an unusually wet year,
however, it does appear that for the Kentucky bluegrass maintained at fairway height there is reason to
believe that higher N levels do reduce discoloration. High N levels may also reduce the effectiveness
o f the growth regulating materials on this species. More work to substantiate these results in a normal
year should be considered.

33

Table 15. Percentage nitrogen in the tissue of Kentucky bluegrass and creeping bentgrass.
Percentage N in Tissue
Kentucky Bluegrass
lbs N/1000 ft2

PreTMT

1st Clipping

2nd Clipping

3rd Clipping

4th Clipping

0.5

3.87

3.58

3.70

3.31

3.52

1.0

4.02

3.83

3.99

3.33

3.78

Creeping Bentgrass
0.5

3.36

4.06

4.85

4.34

4.58

1.0

3.81

4.53

5.06

5.00

4.75

Percentage nitrogen data are the means of 3 replications.

Table 16. Statistical significance of treatment effect, nitrogen level, and the tmt*nitrogen interaction.
Quality Ratings

|

Clipping Weights

Kentucky Bluegrass
Source

6/24

Treatment
Nitrogen

NS
♦♦

7/2
*
♦♦

TMT*N

*

NS

8/3

8/10

8/17

NS
♦♦

7/29
♦♦
♦♦

NS
♦♦

NS
♦♦

NS
♦♦

NS

NS

NS

NS

♦♦

7/8

Treatment

♦*

**

NS

♦♦

Nitrogen

♦♦

NS

NS

**

Creeping Bentgrass
*♦
NS
NS
♦
♦♦
NS

TMT*N

NS

NS

NS

NS

NS

NS

NS

7/16

6/25
*

8/13
4c

8/17
♦

♦4c

♦♦

NS

NS
4c4c

NS

4c

NS

♦♦

**

4c4c

♦

♦♦

4c

4c

NS

♦

NS

NS

NS

NS

Table 17. Quality ratings for the Kentucky bluegrass study.
Nitrogen
Level

7/8

7/29

8/3

8/10

8/17

8

7

8

8

8

8

8

8

9

9

8

8

6

7

7

8

8

7

7

7

8

8

9

9

8

9

8

8

7

7

9

9

6/24

7/2

0.5

7

Control

1.0

7

Primo .75

0.5

Primo .75

1.0

Treatment
Control

Primo 1.5

0.5

5

6

7

Primo 1.5

1.0

7

7

Cutless

0.5

6

7

9
7

9
7

9
8

8

8

Cutless

1.0

7

8

9

8

9

8

8

34

Table 18. Quality ratings for the creeping bentgrass study.

Nitrogen
Level

6/24

7/2

Control

0.5

7

9

Control

1.0

8

8

Treatment

7/8

7/29

8/3

8/10

8/17

7

9

9

8

7

9

9

8
8

Primo .75

0.5

6

8

8
7

8

9

8
7

Primo .75

1.0

7

8

7

9

9

9

9

Cutless

0.5

6

6

7

7

8

7

8

Cutless

1.0

6

7

7

7

7

8

9

Quality is based on a scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality.

Table 19. Clipping weights from the Kentucky bluegrass study.

Treatment
Control

Nitrogen
Level

6/25

7/16

8/3

8/17

0.5

20.6

56.3

238.5

27.9

Control

1.0

18.3

37.2

0.5

16.5

76.3
36.4

261.5

Primo .75

159.0

19.6

Primo .75

1.0

16.5

80.4

264.1

37.5

Primo 1.5

0.5

8.9

34.5

151.4

15.6

Primo 15

1.0

13.7

0.5

14.3

213.2
212.0

26.7

Cutless

67.2
49.7

23.1

13.9

53.7

233.4

23.8

Cutless

1.0

Clipping weights are in grams of tissue from 5 ft x 5 ft plots. Data are the means of 3 replications.

Table 20. Clipping weights from the creeping bentgrass study.

Treatment

Nitrogen
Level

6/25

7/16

8/3

8/17

Control

0.5

8.0

6.1

9.0

34.0

Control

1.0

13.5

8.0

9.7

45.7

Primo .75

0.5

3.8

5.5

5.8

34.2

Primo .75

1.0

5.1

8.0

6.8

58.1

Cutless

0.5

3.6

9.3

4.2

54.2

Cutless

1.0

3.6

10.7

4.4

60.8

Clipping weights are in grams of tissue from 5 ft x 5 ft plots. Data are the means of 3 replications.

35

The Rooting o f Creeping Bentgrass and Kentucky Bluegrass
Treated with Growth Regulating Compounds
N. E. Christians

Growth regulating compounds have the capability of reducing shoot growth of grasses and thereby
reducing the need for mowing. However, there is little information on the effects of many o f the
newer compounds on the root growth of these grass species. The objectives of this study were to
investigate the effects of Primo (Trinexapac-ethyl) and Cutless (Flurprimodol) on the rooting o f
creeping bentgrass and Kentucky bluegrass turf.
The study took place over a two year period at the Iowa State University Horticulture Research Station
north o f Ames, Iowa. The creeping bentgrass area was a 5 year old stand of Penncross creeping
bentgrass maintained at fairway mowing height (0.5 inches). The area receives 4 lbs N/1000 ft2 per
year and is watered as needed to prevent stress. The soil on which the turf was established is a
Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) with a pH of 7.75, P level of 3 ppm, K level o f
48 ppm and an organic matter content o f 2.8%. The Nassau Kentucky bluegrass was maintained at
lawn height (2 inches). The area also received 4 lbs N/1000 ft2 per year. It is established on a
Nicollet soil with a pH of 7.4, P level of 6 ppm, a K level of 74 ppm and organic matter content of
3.5%.
The treatments included an untreated control, Primo at 300 g a.i./ha, and Cutless at 1120 g a.i./ha.
The first application was applied on August 15, 1992. Rooting data were collected on 9/15/92,
9/29/92, and 10/25/92. Data were taken by collecting four 2.5 cm cores to a 20 cm depth. The soil
was washed from the roots o f the cores with a hydropneumatic élutriation machine as described by
Smucker (Agron. J. 74:500-503). The roots were oven dried for 24 hours at 75°C, weighed, ashed in
a muffle furnace at 500°C for 24 hours and weighed again. Rooting was reported as the difference in
weight between oven dried and ashed root samples. Quality data were also collected on a scale o f 9 to
1, 9 = best quality, 1 = dead turf, and 6 = acceptable quality.
The study was repeated in 1993 on the same plot areas. The same rates of Primo and Cutless were
applied on 5/10/93 and 6/11/93. Rooting data were collected in the same way as previously described
at 4 weeks after the first application on 6/11, just before the second application. Rooting data were
scheduled for collection at 4, 6, 8, 10, and 12 weeks after the first application. Actual data collection
occurred at somewhat different intervals due to the very heavy rains of 1993 (Tables 23 and 24).
Quality data were collected throughout the test period as described earlier.
The weather in the fall of 1992 was normal for Iowa and some irrigation was required to maintain the
plots. The summer o f 1993 was the wettest in recorded history with more than 40 inches of rain
recorded during the test period (Figure 1 Page 28). The plot area was saturated through much of this
period.
In 1992, there was some initial reduction of turf quality on Kentucky bluegrass by both Primo and
Cutless, but at no time did the ratings drop below an acceptable level of 6 (Table 22). There was
some initial discoloration of creeping bentgrass, but no statistically significant differences occurred
(Table 21). No reductions in creeping bentgrass quality were observed on 9/15 or 9/29.
Numerical reductions in root weights of creeping bentgrass by both Primo and Cutless were observed
at the 9/15 collection date, but the reductions were not significantly different (Table 21). No
reductions in rooting of bentgrass were observed at either 9/29 or 10/25. There was no reduction o f
Kentucky bluegrass rooting on 9/15 (Table 22). Significant reductions in Kentucky bluegrass were
36

measured on 9/29 in response to applications of both Primo and Cutless. A significant increase in
rooting beyond that observed in the control was measured in plots treated with Cutless on 10/25. This
may have been due to a postinhibitory stimulation. No reduction of rooting on plots treated with
Primo was observed on 10/25.
The soil in the test area was saturated through much of the 1993 test period. Soil cores were collected
during brief dry periods that occurred during the season. Cutless resulted in initial reductions in turf
quality below acceptable levels (Table 23). The grass treated with Cutless recovered later during the
very wet period of mid-summer. Quality was not reduced below acceptable levels following the
second treatment on 6/11/93. There was some initial reduction in quality of grass treated with Primo,
but at no time did quality ratings fall below acceptable levels. Quality ratings of Kentucky bluegrass
treated with Cutless fell below the acceptable level following the second application (Table 24). By
7/29, the Kentucky bluegrass treated with Cutless had recovered, although ratings were still below that
o f the control. By August, complete recovery had occurred. Primo reduced quality ratings slightly
through much o f the summer, as compared to the control, but at no time did ratings fall below an
acceptable level o f 6.
There were some numerical reductions in rooting measured in plots of creeping bentgrass and
Kentucky bluegrass in response to both Primo and Cutless (Tables 23 and 24). At no testing date
were these reductions found to be statistically significant.
Although it is difficult to draw final conclusions from data collected in such an unusual season as was
experienced in 1993, it is apparent from the two years of data reported here that both Primo and
Cutless have little impact on rooting of Kentucky bluegrass and creeping bentgrass managed under
these conditions.
Table 21. The effects of Primo and Cutless on the turf quality and rooting of creeping bentgrass in 1992.
8/29/92
Treatment

9/15/92

9/29/92

9/15/92

9/29/92

10/25/92

Root Weight (g)

Quality Rating*

1. Control

9

9

9

0.1248

0.0719

0.0451

2. Primo 25 WP

7

9

9

0.0512

0.0784

0.0463

3. Cutless 50 WP

7

9

9

0.0552

0.0652

0.0500

NS

NS

NS

NS

NS

NS

LSDaos

Table 22. The effects of Primo and Cutless on the turf quality and rooting of Kentucky bluegrass in 1992.
8/29/92
Treatment

9/29/92

9/15/92

9/15/92

9/29/92

10/25/92

Root Weight (g)

Quality Rating*

1. Control

9

9

9

0.0184

0.0374

0.0360

2. Primo 25 WP

7

8

8

0.0237

0.0225

0.0349

3. Cutless 50 WP

8

9

9

0.0292

0.0238

0.0494

1.0

1.0

1.0

NS

0.0111

0.0112

LSDao5

Quality is based on a scale of 9 to 1: 9 = best, 6 = acceptable, and 1 = poorest quality.
Root weight are the difference between oven dried root samples and ashed weights of 4, 2.5 cm diameter, 20 cm deep
samples from each treated plot.

37

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Primo Grass Seed Germination Study - 1993
T. Roethler and N.E. Christians

The objective of this experiment was to determine if Primo affects the germination and establishment of
creeping bentgrass, Kentucky bluegrass, and perennial ryegrass.
An experiment was conducted in the field at the Iowa State University Horticulture Research Station north
o f Ames, Iowa, and in the Iowa State University Horticulture greenhouse. The project at the research
station was established on 8/26/93 and the greenhouse study was established on 10/23/93.

Field Study
The field study was conducted as a split plot with the Primo treatments as main plots and the 3 grass
species as sub plots. The study was replicated 3 times. The growth regulator main plots measured 5 ft
by 5 ft. They were divided evenly into 3 sections and planted with the 3 grasses: Penncross creeping
bentgrass at 1.0 lb/1000 ft2, Bronco Kentucky bluegrass at 1.5 lb/1000 ft2, Manhattan II perennial ryegrass
at 3 lb/1000 ft2.
The three Primo treatments were as follows:
1.
2.
3.

Control
Primo at 0.5 oz/1000 ft2 (0.36 ml/plot)
Primo at 1.0 oz/1000 ft2 (0.72 ml/plot)

The treatments were applied in 285 ml of water/plot (approximately 3 gal/1000 ft2). Data were collected
on days to germination and on percentage cover following germination for 9 weeks.

Greenhouse Study
The objective o f the greenhouse study was to determine if the three species used in the field study were
affected by very high rates of Primo. This study was established on 10/23/93.
Seventy-two 3.5 inch by 3.5 inch pots were filled with soil from the ISU field area. Each pot was 0.085
ft2 in surface area. The same seed was used as in the outdoor experiment. Twenty-four pots were seeded
with the Kentucky bluegrass, twenty-four with creeping bentgrass, and twenty-four with the perennial
ryegrass. The seeding rates were the same as in the field: Kentucky bluegrass at 1.5 lb/1000 ft2 = 0.0578
g/pot, creeping bentgrass at 1 lb/1000 ft2 = 0.0385 g/pot, perennial ryegrass at 3 lbs/1000 ft2 = 0.116 g/pot.
The Primo rates used in the greenhouse were much higher than the outdoor experiment to determine what
effects extremely high rates would have on germination. The rates were as follows:
Treatment

ml Primo/pot

Dilution

1. Control

0.0

0

2. Primo at 1 oz/1000 ft2

0.002454

3. Primo at 2 oz/1000 ft2

0.005

25 ml in 175 ml

4. Primo at 4 oz/1000 ft2

0.01

50 ml in 150 ml

5. Primo at 8 oz/1000 ft2

0.02

1600 ml in 100 ml

6. Primo at 16 oz/1000 ft2

0.04

200 ml

12.5 ml in 187.5 ml

39

The study was conducted as a split plot in 4 replications with the species as main plots and the primo
treatments as sub plots.
The pots were initially irrigated with 50 ml of water and the pots were watered regularly throughout the
experiment when needed. Data were initially taken daily to record the days to germination and percent
cover of the pots was recorded weekly for 9 weeks. Clipping weight was taken at the end o f the study.
The results of the field study showed that at recommended rates there was no substantial effect on the
germination or establishment of the 3 grass species (Table 25). No visual differences were recorded
among treatments at any time during the 9 week study period.
In the greenhouse study, there was no effect on the germination of the 3 species, as was the case in the
field. But there was a difference in percent cover and clipping weight at the higher rates of Primo.
Clipping weight decreased as the treatment rates increased uniformly for all species and the data for all
three species were combined for analysis (Table 26). The control treatment had an average weight of
1.268 g while treatment 6 had an average clipping weight of 0.292 g, showing a dramatic effect at the
higher treatments. There was a significant species by treatment interaction on percent cover over the 9
week test period (Table 27). Kentucky bluegrass showed a slight drop in percent cover as the rates
increased. The final cover of the control was 75%, while treatment 6 had a final cover of 67%. The
creeping bentgrass followed the same pattern as the Kentucky bluegrass, with a drop from 91% cover to
66% cover from the control to treatment 6. Perennial ryegrass appears not to have a substantial affect on
the percent cover at any level of the treatments (Table 27).
In conclusion, no effect was observed on the germination of Kentucky bluegrass, creeping bentgrass, or
perennial ryegrass at the recommended rate of Primo. However, there may be an affect on percent cover
and clipping weight at higher rates. One must keep in mind though that Primo is recommended at much
lower rates than were used in the greenhouse.

Table 25. The effects of Primo on germination of three grass species in the field.
Number of Weeks Following Establishment
2

1
Grass Species
Kentucky bluegrass

Creeping bentgrass

Perennial ryegrass

LSD((X05)

3

4

5

6

7

8

9

Primo
Treatment

Days

Control

6

3

5

7

8

33

37

41

50

67

0.5 oz/1000 ft2

6

3

5

7

8

38

41

46

50

69

1.0 oz/1000 ft2

7

2

5

7

8

38

41

45

50

70

Control

8

0

2

3

3

7

8

10

12

18

0.5 oz/1000 ft2

8

0

2

3

3

4

6

8

10

15

1.0 oz/1000 ft2

8

0

2

3

3

6

8

9

10

16

Control

4

18

21

26

43

60

73

77

80

88

0.5 oz/1000 ft2

4

18

20

25

42

60

73

77

80

90

1.0 oz/1000 ft2

4

18

20

25

40

58

73

76

78

88

NS

NS

NS

NS

NS

NS

NS

NS

NS

Percent Cover

40

Table 26. The effect o f Primo on the average clipping weight of the three species in the greenhouse.
Treatment

Clipping Weight

1

1.268

2

1.131

3

0.935

4

0.696

5

0.475

6

0.292

LSD(0.05)

0.05

Table 27. The effect of Primo on the percent cover of the three species in the greenhouse study.
Species
Kentucky bluegrass

Creeping bentgrass

Perennial ryegrass

Primo Treatment

Percent Cover

1

75

2

71

3

72

4

74

5

67

6

67

1

91

2

86

3

87

4

84

5

76

6

66

1

84

2

85

3

82

4

83

5

82

6

82

41

1993 CIBA Primo Study
M. L. Agnew

Objectives:

1) To evaluate the effects of Primo on the growth and quality o f ’Midnight’ Kentucky
bluegrass;
2) To compare the effects of Sprint 330 when added to 2 rates o f Primo 1 EC;
3) To evaluate the benefits o f adding nitrogen to Primo 1 EC.

This study was established at the Iowa State University Horticulture Research Station north o f Ames,
Iowa, on an 8-year- old stand of Poa pratensis ’Midnight’. The soil on the test area is a Nicollet
(fine-loamy, mixed, mesic Aquic Hapludoll) with 3.3% organic matter, a pH o f 7.1, 7 ppm P, and 109
ppm o f K.
Treatments:

Rate foz / 1000 ft2)
0.50
0.75
0.50 + 1.0
0.75 + 1.0
0.40
0.75 + 21.0

Product
1. Primo 1EC
2. Primo 1EC
3. Primo 1EC + Sprint 330
4. Primo 1EC + Sprint 330
5. Primo 25WP
6. Primo 1EC + CoRoN
7. Check

The turf was maintained as a 2 inch mowing height and irrigated to prevent moisture stress. Plot
measured 5 ’ X 5 ’ and were randomized in a complete block design. All plots were fertilized on May
15, 1993 with 1.0 lb N/1000 ft2 as sulfur coated urea (37-0-0).
Treatments were applied on May 20, and July 23, 1993 with a pressurized backpack sprayer. The
May 20 application was made at 10:45 am and the soil temperature was 55°F. The July 23 application
was at 9:30 am and the soil temperature was 78°F.
Data collected during the summer o f 1993 included visual quality, clipping yields and thatch
development. All plots were rated weekly on a visual scale of 9 to 1: 9 = dark-green, dense turf, 6 =
m inim um acceptable quality, and 1 = straw-brown turfgrass stand. Clipping yields were collected on a
weekly basis or when enough grass was present to collect. Clippings were collected by removing all
the leaf tissue above 2 inches within a 21 in by 5 ft area (8.75 ft2) down the center of each plot.
Qippings were placed in paper sacks and dried. Weights were recorded as grams per 8.75 ft2. Plots
were rated for seed head development on June 15, 1993, as percent of plots covered with seedheads.
Plots were rated on August 8, 1993, for phytotoxicity damage. A scale of 1 to 5: 1 = no damage and
5 = brown turf was used.
The weather in 1993 can be classified as cool and wet. For 36 days after application (DAA) in the
spring the high temperature only reached 85°F one time and the cumulative rainfall reached over 8
inches (Figure 2). The temperatures were warmer after the second application, but not considered to
be excessive (Figure 3). The cumulative rainfall was over eight inches, 24 DAA.
The visual quality, seed head development and phytotoxicity data is presented in Table 28. Primo (0.5
rate) + Sprint and Primo (0.75 rate) + CoRoN provided improved quality over the control and other
Primo treatments on May 30. The Primo (0.75 rate) + CoRoN provided improved quality over the
control and other Primo treatments on July 23, September 8 and overall. A greater amount of seed
heads were noted on turf treated with Primo. This was largely due to the seed heads being removed

42

on other plots at earlier mowings. The seed heads will set lower in the grass on the Primo treated
plot. The phytotoxicity ratings showed that Primo (0.75) sustained the greatest amount of damage.
The addition o f CoRoN negated any phytotoxic effects.
Clipping yield data is presented in Table 29. The totals are separated into spring application and
summer application. All primo treated plots reduced clippings during the spring. The clipping
production after the summer application demonstrated that the initial nitrogen application was depleted.
The addition of CoRoN increased the overall clipping during this time period, and significantly
improved the quality.
The cumulative clipping yields are presented in Figures 3 and 4. For the spring application, the
greatest increase in clipping accumulation occurred 20 DAA, and accumulation tapered off by 40
DAA. For the summer application, the accumulation of clipping were more gradual than in the
spring.
Primo treated plots successfully reduced clipping production while having very little effect on visual
quality. Because the summer of 1993 was very cool and wet, the effect of the sprint application were
not evident. However, it is very clear from these trials that nitrogen application is very important to
maintain minimal growth and quality.

43

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CO
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Cumulative Rainfall (inches)

Figure 3. Summer Application Weather Data

Days After Application

45

Figure 4.

Cumulative Clipping Yields Following Spring Application

Figure 5. Cumulative Clipping Yields Following Summer Application

46

The Effect o f Ethofumesate (Prograss) on a Putting Green at
Veenker Memorial Golf Course in
Iowa
J. B. Unruh, J. Livingston and N. E. Christians

Ethofumesate (Prograss) is marketed as an annual bluegrass
annua) control for golf course
fairways. It is labeled for use on Kentucky bluegrass (Poa pratensis), perennial ryegrass (Lolium
perenne), and creeping bentgrass (Agrostis palustris) maintained at fairway mowing heights. It is not
labeled for low-mowed creeping bentgrass on putting greens.
The objective of this study was to assess annual bluegrass control in addition to injury to creeping
bentgrass from ethofumesate applications. Additionally, the effect of fertilizer on injury to creeping
bentgrass caused by ethofumesate was determined.
The experiment was initiated on September 24, 1994 and treatments were applied as indicated in Table
30. Plots measured 5 ft by 5 ft. and were situated on the practice green at Veenker Memorial Golf
Course in Ames, Iowa. Phytotoxicity data were taken 3.5 weeks after initial ethofumesate treatment.
Turf quality and density estimates were taken on April 4, 1994 and April 29, 1994. Density estimates
were obtained by visually estimating the percentage of annual bluegrass, creeping bentgrass or dead
grass contained within the area o f a small wire grid. This procedure was done at three randomly
determined locations within the plot area.
Phytotoxicity ratings taken 3.5 weeks after treatment revealed that only the 0.75 lb rate (without
fertilizer) yielded any appreciable damage. These plots, however, were still at an acceptable level.
Initially in the spring, treated plots exhibited less than acceptable quality, with the fertilizer
supplemented plots being the best among treated plots. The lower rates of ethofumesate significantly
reduced the annual bluegrass density.
By April 29, the quality o f the plots were all above the acceptable level except for the 0.56 lb rate
plots. This could be because of the significant amount of dead grass within the plots. All four
treatments significantly reduced the annual bluegrass density within the plots, however, there were no
differences among treatments.

47

Table 30. The effect of Ethofumesate (Prograss) treatment on a Putting Green

I

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1

Turfgrass Disease
and Insect Research

Evaluation of Fungicides for Control of
Snow Molds on Creeping
1993-1994
M. L. Gleason

The trial was conducted on a bentgrass green (cv. unknown) at the Nashua Town and Country Qub
Golf Course, Nashua, IA. This green has a high thatch content, is subject to drifting snow, and has
had severe outbreaks o f snow mold in most of the last 10 years. The experimental design was a
randomized complete block with 4 replications. All plots measured 5 ft x 5 ft. Fungicides were
applied on November 17, 1993, using a modified bicycle sprayer at 30 psi and a dilution rate of 5
gal/1000 ft2.
Snow cover persisted from about January 1 until March 20, 1994. On March 23, symptoms of gray
snow mold were evident on the part of the green where snow cover persisted longest. Snow mold
development on untreated check plots was light, with an average of less than 10% o f the plot area
symptomatic (Table 31). All fungicide treatments gave significantly better control of snow mold than
the untreated check, except TRA 0028 at 8 oz + Chipco 26019 Flo at 4 oz, BAS 490 at 0.0064 g a.i.,
and BAS 490 at 0.0129 g a.i. No phytotoxicity symptoms were observed.

Company
Grace-Sierra

ISK Biotech

1993-1994 evaluation of fungicides for control of snow molds on creeping bentgrass at
Nashua Town & Country Club Golf Course, Nashua, IA.
Rate/1000 ft2

Product

Disease Ratine2

Check

1.75 a

GS/SM 93-01

0.25 b

GS/SM 93-02

0.00 b

GS/SM 93-03

0.00 b

GS/SM 93-04

0.00 bc

GS/SM 93-05

0.33 bc

GS/SM 93-06

0.00 bc

GS/SM 93-08

0.25 b

GS/SM 93-09

0.00 b

GS/SM 93-10

0.00 b

GS/SM 93-11

0.00 b

GS/SM 93-12

0.00 b

GS/SM 93-13

0.00 b

Fluazinam 500
Fluazinam 500+

1.0 oz.

Daconil F
ASC67153 SC
Daconil F+

oz.
oz.

0.25 b

o
od

0.00 b
0.00 b

O
00

2.5 OZ.

00
b

Table 31.

oz.

0.00 b

ASC67103

16 ml

Fluazinam 500

1.0 oz.

49

0.33 bc

Company
Terra

Rhone-Poulenc

Ciba-Geigy

BASF

Product

rate/1000 ft2

Disease Rating3

Thalonil 90+

4.5 oz.

0.25 b

Chipco 26019FLO

4 fl. oz.

Thalonil 90+

9 oz.

Chipco 26019FLO

4 fl. oz.

TRA 0028+

8 fl. oz.

Chipco 26019FLO

4 fl. oz.

TRA 0028+

16 fl. oz.

Chipco 26019FLO

4 fl. oz.

Chipco 26019+

4 oz.

0.00 b
0.75 ab
0.00 b
0.00 b

Daconil 2787

8 oz.

Chipco 26019+

8 oz.

Daconil 2787

8 oz.

CGA 173506 50WP+

3.5g a.i.

Banner 1.1 ED

2 oz.

CGA 173506 50 WP

7g a.i.

0.00 b

Banner 1.1 EC

4 oz.

0.00 b

BASF Exp.

.0032g a.i.

0.00 bb

BASF Exp.

.0064g a.i.

1.50 a

BASF Exp.

.0129g a.i.

1.00 abb

0.00 b
0.00 b

“Means of four replications unless otherwise noted (bn=2, cn=3). 0 = no disease; 1 = 1-5% o f plot
showing symptoms: 2 = 5-10% of plot; 3 = 10-25%; 4 = 25-50% o f plot 5 = >50% o f plot. Means
followed by the same letter are not significantly different (DMRT, P=0.05).

50

Evaluation of Fungicides for Control of Brown Patch
in Creeping Bentgrass — 1993
Mark L. Gleason

Trials were conducted at Veenker Memorial Golf Course on the campus of Iowa State University,
Ames, IA. Fungicides were applied to creeping bentgrass maintained at 5/32-inch cutting height, using
a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1000 ft2. The experimental design was
a randomized complete block with three replications. All plots measured 4 ft x 5 ft. All plots were
surrounded by 1-ft-wide strips of untreated turf in order to help create uniform disease pressure.
Fungicide applications began on June 11 and were repeated at recommended intervals on June 19 and
25 and July 2, 9, 16, 23, and 30. Disease development was rated on July 14, July 30, and August 6.
The summer o f 1993 was the wettest in Iowa since 1851. Heavy, frequent rainfall in June through
August favored disease development, but below-normal temperatures helped to suppress brown patch.
Disease pressure on the test plot was moderate to severe on July 14 and August 6 and severe on July
30.
Most formulations suppressed disease significantly on each rating date. Several treatments provided
excellent control on all rating dates; two treatments, 1) Thalonil 90 and 3.5 oz and 2) TRA 0028 at
6.0 oz on 14-day intervals, showed no disease on all dates. No phytotoxicity was observed for any
treatments.
PCNB 75 W formulations at the 4-oz rate and 7-day intervals caused moderately severe yellowing and
browning o f the turf in July and August. Sentinel 40 WG caused a slightly enhanced green color of
the turf by early August.

51

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o Z

Evaluation of Fungicides for Control of
Dollar Spot in ’Penncross’ Bentgrass - 1993
Mark L. Gleason

Trials were conducted at the Iowa State University Horticulture Research Station north o f Ames, Iowa.
Fungicides were applied to Penncross creeping bentgrass maintained at 5/32-inch cutting height, using
a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1000 ft2. The experimental design was
a randomized complete block with four replications. All plots measured 4 ft x 5 ft.
Fungicide applications began in early June, following inoculation with infested rye grain. However,
due to a communication error, the plot had been sprayed with Daconil 2 weeks earlier, so the
inoculation was ineffective. Sprays were discontinued on June 30. The plot was reinoculated on
August 1, and all treatments were reapplied on August 6. Subsequent applications were made at
specified intervals on August 13, 20, and 27. Disease development was rated on July 30 (before the
reinoculation), August 20, and September 3.
Disease development was severe during the test period, which was unusually rainy (twice the normal
rainfall total during August). Two materials were not significantly better for disease control than the
untreated check on the August rating dates: Thalonil 90 at 3.5 oz and TRA 0028 at 6 oz at a 14-day
interval. Other treatments varied widely in efficacy. No phytotoxicity symptoms were observed.

53

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dum ber of infection centers per plot.
inoculation with infested grain was done on August 1.
3Numbers in a column followed by the same letter are not significantly different (DMRT, P=0.05).

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3

Evaluation of Fungicides for Control of
Leaf Spot in ’Park’ Bluegrass - 1993
Mark L. Gleason

Trials were conducted at the Iowa State University Horticulture Research Station north of Ames, Iowa.
Fungicides were applied to Kentucky bluegrass (cv. Park) maintained at 2 1/2-inch cutting height,
using a modified bicycle sprayer at 30 psi and a dilution rate of 5 gal/1000 ft2. The experimental
design was a randomized complete block with four replications. All plots measured
4 ft x 5 ft.
Fungicide applications began on June 10 and continued at recommended intervals (14 or 21 days) until
August 12. Disease development was rated on July 14, July 30, and August 18.
Disease development was light to moderate during the test period, which was unusually rainy. Several
compounds suppressed disease significantly in comparison to the untreated check on each rating date.
Daconil SDG at 3.8 oz and a 14-day interval gave the most consistent disease control, closely followed
by ASC 67098 at 6.0 oz and a 14-day interval. No evidence of phytotoxicity was observed during the
test period.

55

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56

Potential Control o f Symptom Expression by Leaf Spotted
(Bipolaris sorokiniana) Kentucky Bluegrass Leaves
C. F. Hodges and D. A. Campbell

Bipolaris sorokiniana is the cause of leaf spot of Kentucky bluegrass throughout the north central
states and is a serious pathogen of numerous grass species (turf and non-turf) world wide (11,12). In
addition to the attack o f leaves, this pathogen can infect crowns, roots, inflorescence, and germinating
seedlings. The leaf infecting stage of the disease can be found throughout the growing season. Leaf
spot damage is common in the spring, but the environmental conditions of fall provide optimum
conditions for severe leaf spotting and chlorosis (9, 10). The fall season with periods of prolonged
overcast, cool, wet, weather and progressively shorter daylengths increase the extent to which infected
leaves yellow.
Research in our laboratory over several years has established that the physiology of yellowing of
infected leaves is related to senescence, ethylene, and a nonspecific phytotoxin produced by the
pathogen (1, 6, 8). Yellowing is typically most severe in the fall on older infected leaves. This is due
to enhancement o f the rate of leaf senescence in response to shorter daylengths; a condition that is
exploited by the pathogen. The interaction can be further enhanced by postemergence herbicides (4, 5,
7) and perhaps nitrogen fertilization (2, 3). The actual cause of yellowing o f infected leaves is due in
large part to the production of endogenous ethylene during the infection process. The phytotoxin
produced by the pathogen also seems to cause some direct yellowing at the margin of the lesions
formed on the leaves.
Traditional approaches to the control of B. sorokiniana leaf spot of Kentucky bluegrass have included
a combination cultural practices and application of fungicides. The cultural approaches include
moderate nitrogen fertilization, thatch reduction, raising mowing heights, avoidance of afternoon and
evening irrigation, and the use of resistant cultivars. Cultural practices generally have only a modest
affect on controlling this pathogen and resistant cultivars tend to be regionally effective and the nature
of the resistance is often precarious over time and with environmental stress. Several fungicides are
effective against B. sorokiniana (11), but the quantities required and their cost become a major factor
in their use. This pathogen can be exceptionally costly to control because it can be active on some
portion of the plant during the entire growing season.
In that we grow turf for its aesthetic value, it might not be necessary to prevent infection o f Kentucky
bluegrass leaves by B. sorokiniana, if we could inhibit the yellowing symptoms that occur following
infection. If for example, the biosynthesis of ethylene could be prevented during infection, the
yellowing o f the leaves would be substantially reduced. The presence of small lesions on the leaves
without yellowing would be of little consequence to the aesthetic value of the turf, and the infected
leaves would be periodically removed with mowing. The research conducted in our laboratory over
the last three years has examined the potential for preventing the yellowing of Kentucky bluegrass
leaves infected by B. sorokiniana.
OBJECTIVES OF RESEARCH
The primary objective o f this research project has been to evaluate substances known to prevent the
biosynthesis and/or mode of action of the endogenous ethylene generated during the infection of
Kentucky bluegrass by Bipolaris sorokiniana. Control of this process could feasibly reduce or
eliminate the use o f fungicides for the control of this disease (and possibly others) by preventing the
yellowing associated with disease development.

57

RESEARCH OBSERVATIONS
The primary source of endogenous ethylene during infection is from the biosynthetic pathway in the
host plant. Some ethylene also is produced by the pathogen from a second pathway, but the amount is
believed to be negligible in most cases. Therefore, the biosynthesis and/or mode of action o f
endogenous ethylene produced by the host has been targeted for control. The following substances
have been evaluated for their ability to prevent the biosynthesis of ethylene during the infection
process and to prevent or reduce yellowing of the leaves:
1.
2.
3.
4.
5.
6.

Aminooxyacetic Acid (AOA)
Aminoisobutyric Acid (AIB)
Canaiine (CAN)
Carbonyl Cyanide m-Chlorophyenylhydrazone (CCCP)
Còbalt Chlorophylloride (COCL)
Propyl Gallate (PG)

Ten milliliters o f each substance at concentrations of 10'3M were applied to the soil in pots containing
Kentucky bluegrass each of 3 days preceding inoculation, and then each of 4 days during pathogenesis
which included the assay days for endogenous ethylene evolution by the infected leaves. The four
youngest visible leaves were inoculated with four agar plugs (4mm) containing the mycelium o f the
pathogen.

1.

Ethylene Production:
Inoculated plants were assayed for endogenous ethylene generation at 24, 48, 72, and 96 hours
after inoculation. The normal levels of endogenous ethylene in healthy leaves ranged from
0.28 to 0.32 pi l*1. All ethylene inhibiting substances, except AIB, decreased endogenous
ethylene at one or more of the four 24h sampling periods.
None o f the ethylene inhibiting substances applied to the roots of Kentucky bluegrass
prevented infection by B. sorokiniana and lesion development was typical of that on inoculated
control plants. Ethylene in nontreated, inoculated plants increased to 1.48 pi l'1 at 48 hours
after inoculation. All ethylene inhibiting substances decreased the surge of endogenous
ethylene at 24h and 48h during the early stages of pathogenesis. At 72h, as pathogenesis
progressed, AIB and COCL ceased to decrease ethylene evolution. CAN, AOA, CCCP, and
PG continued to decrease endogenous ethylene production at 72h and 96h. AOA and CAN
were among the more consistent substances at decreasing endogenous ethylene in inoculated
leaves; these materials held the ethylene in a range of 0.4 to 0.9 pi l'1 over each o f the 24 hour
observation periods.

2.

Chlorophyll Loss:
Inoculation of leaves of untreated control plants with B. sorokiniana decreased the chlorophyll
content of the leaves to 43% of that in healthy control leaves at 96h after inoculation.
Ethylene inhibiting materials applied to the roots o f healthy plants did not significantly change
the chlorophyll content of the leaves. Plants treated with AIB, CCCP, COCL, and PG and leaf
inoculated with B. sorokiniana failed to prevent the loss o f chlorophyll during pathogenesis.
Inoculated plants treated with CAN and AOA substantially decreased the loss o f chlorophyll
compared to that of inoculated control plants. Inoculated leaves of plants treated with CAN
and AOA retained 74% and 80% of their chlorophyll, respectively.

58

CONCLUSIONS AND OUTLOOK
1.

CAN, AO A, CCCP, and PG proved effective in decreasing the surge o f endogenous ethylene
during infection when applied to the roots of inoculated plants. However, only CAN and
AOA maintained a substantial portion of the chlorophyll during pathogenesis. The treatment
of roots did not prove as effective as we had hoped and we are now in the process of
conducting foliar application tests that we believe will be more effective with a broader
spectrum o f materials. The primary drawback of foliar application is the possibility of
increased phytotoxicity. Preliminary observations with foliar applications o f CAN and AOA
look more promising than the results obtained with soil treatments. Other considerations
relative to the observations of this research are presented below.
a.

b.

The soil treatment studies conducted in this project utilized very high levels of
inoculum in an effort to see how effective the materials tested could be at containing
ethylene production and subsequent chlorophyll loss. In retrospect, it is probable that
the inoculum pressure exerted by this approach simply overwhelmed the plant tissue
and any good that the substances being tested might have done. The inoculum levels
originally used would be several hundred times greater than any level encountered in
the field. Foliar treatments are currently being reexamined with substantially lower
levels of inoculum and somewhat different environmental parameters. This could
make a major difference in the results.
It is unlikely that the ethylene inhibiting substances alone will prevent loss of
chlorophyll from infected leaves. Some chlorophyll loss may be related to other
hormones and to senescence induced by the pathogen. Work on the potential
manipulation of these factors will be a goal of future research. Control of senescence
physiology is another primary goal. If senescence retardation can be achieved and
combined with a decrease in ethylene (which induces senescence) production, the
potential for symptom expression control is very good.

ACKNOWLEDGEMENT
The research presented in this report was supported, in part, by a grant from the Green Section, United
States Golf Association.

59

LITERATURE
1.

Coleman, L. W., and Hodges, C. F. 1987. Ethylene biosynthesis in
pratensis leaves in
response to injury or infection by Bipolaris sorokiniana. Phytopathology 77:1280-1283.

2.

Cheeseman, J. H., Roberts, E. C., and Tiffany, L. H. 1965. Effects of nitrogen level and
osmotic pressure of the nutrient solution on the incidence o f Helminthosporium sativum
infection in Merion bluegrass. Agron. J. 57:599-602.

3.

Couch, H. B., and Moore, L. D. 1971. Influence of nutrition and total non-structural
carbohydrate content on Helminthosporium
Phytopathology 61:888 (abstr.).

isncited leaf

4.

Hodges, C. F. 1980. Interaction of sequential leaf senescence o f Poa pratensis and
pathogenesis by Drechslera sorokiniana as influenced by postemergent herbicides.
Phytopathology 70:628-630.

5.

Hodges, C. F. 1984. Drechslera sorokiniana leaf spot development on sequentially senescent
leaves of Poa pratensis exposed to postemergence herbicide combinations. Plant Dis.
68:213-215.

6.

Hodges, C. F., and Coleman, L. W. 1984. Ethylene-induced chlorosis in the pathogenesis o f
Bipolaris sorokiniana leaf spot of Poa pratensis. Plant Physiol. 74:462-465.

7.

Madsen, J. P., and Hodges, C. F. 1984. Effect of chlorophenoxy herbicides on free amino
acids in sequentially senescent leaves of Poa pratensis and on pathogenesis by Bipolaris
sorokiniana. Phytopathology 74:1407-1411.

8.

Hodges, C. F. 1990. Endogenous ethylene response and chlorophyll loss in sequentially older
leaves of Poa pratensis infected by Bipolaris sorokiniana. J. Plant Physiol. 136:670-674.

9.

Nilsen, K. N., Hodges, C. F., and Madsen, J. P. 1979. Pathogenesis of Drechslera
sorokiniana leaf spot on progressively older leaves of Poa pratensis as influenced by
photoperiod and light quality. Physiol. Plant Pathol. 15:171-176.

10.

Nilsen, K. N., Madsen, J. P., and Hodges, C. F. 1979. Enhanced Drechslera sorokiniana leaf
spot expression on Poa pratensis in response to photoperiod and blue-biased light. Physiol.
Plant Pathol. 14:57-69.

11.

Smith, J. D., Jackson, N., and Woolhouse, A. R. 1989. Fungal diseases o f amenity turf
grasses. E. & F. N. Spon. New York.

12.

Sprague, R. 1950. Diseases of cereals and grasses in North America. Ronald Press. New
York.

60

The Screening o f Allelopathic Compounds
as Potential Herbicides
D. A. Campbell and N. E. Christians

Laboratory petri dish germination and greenhouse pre- and postemergence treatment studies were
initiated to determine the efficacy o f certain water soluble and less soluble compounds, identified in
the literature as having allelopathic activity in other plant species, to inhibit the germination of Lolium
perenne (perennial rye).

Procedure
Initially four compounds were investigated Arbutin, Catechol (Pyrocatechol), Camphor, and Tannic
acid. Of these four, Camphor was dropped due to it’s relatively insoluble nature.
In addition five more compounds (Aloin (Barbaloin), Esculin, Gramme, Succinic acid, and Syringic
acid) were investigated. Plant survival data were also collected.
All compounds were brought into solution at various Molar (M) concentrations using distilled water
(Table 35 & 36). A petri dish germination inhibition assay was initiated using 1 ml of the various
Molar concentrations on a 7 cm piece of Whatman #1 filter paper disk in a 15 x 100 mm disposable
petri dish. After applying the solution to the filter paper, 10 seeds of Lolium perenne were placed
equidistantly over the surface. The dishes were then wrapped with two layers o f Parafilm and placed
in a growth chamber with 8 hours o f light per day and 25°C day and 15°C night. The seeds were
allowed to germinate for 14 days with data taken at days 7 and 14. In addition to total germination
inhibition (the ability of a compound to completely stop the emergence of either the root radical or
coleoptile through the seed coat), visual observations were made to assess the degree to which the
compounds retarded normal development of the root or shoot compared to the heathy control
seedlings. Three separate replicated studies were conducted with each of these compounds to obtain
the data.
Greenhouse assays were preformed using 4" X 4" pots filled with field soil to 1/2" below the top. The
seed bed was firmed and 0.309 g (8 lbs/1000 ft2) of perennial rye seed were applied. The seeds were
then covered with 28 cm2 o f field soil. Preemergence assays were performed by applying 2.5 ml of
the compound per pot, to the soil surface by atomizing with a DeVilbiss 561 series air compressor and
an atomizing nozzle to assure complete, uniform coverage. After preemergence treatments were
applied, the pots were placed on a mist bench for 24 hours to water in, as is commonly done with
commercial preemergence products. Postemergence applications were done by using the same
procedure as above to establish a stand. Seedlings were then allowed to grow until the first leaf
reached a height o f 5 cm. The treatments were then applied at the same rate in the same fashion as
above, but on the established leaf tissue. Treated seedlings were allowed to stand for 48 hours without
watering.

Results
In the petri dish assay Tannic Acid and Catechol were effective at completely inhibiting germination at
-1 Molar (1 x 10_1M) concentrations, while Arbutin effectively inhibited germination by 75% at that
concentration. At the -2M concentration Tannic Acid, Catechol and Arbutin inhibited germination
17%, 22% and 0% respectively. The -3M concentrations of these compounds offered little
germination inhibition (0 - 2%) (Table 35).

61

Visual observations of the -2 and -3 Molar concentrations of Tannic Acid, Arbutin, and Catechol
offered more interesting results than the percent of inhibition would indicate (Table 35). Tannic Acid
at the -2M concentration caused a 30% reduction in shoot length and a 80% reduction in root length,
at -3M it caused little shoot reduction and a 50% reduction in root length. Arbutin while inhibiting
germination by 75% at -1M caused a 50% reduction in shoot length and 100% inhibition o f root
formation in the seedlings that did emerge. At -2M a 30% reduction in shoot length was observed
with a 90% reduction in root length. The -3M concentration showed little effect on either shoot or
root length. Catechol at -2M caused a 80% reduction in shoot length and a 80% reduction in root
length in the seedlings that did germinate. At -3M little shoot reduction was observed with a 20%
reduction in root length (Table 35).
Petri dish germination assays o f the five new compounds showed that only one had any effect on
germination. Succinic acid at -1M ( I X 10_1M) concentration, with germination being reduced to
37.5% o f non-treated control (Table 1A). Inhibition was not present at the -2M concentration.
Visual observation of the shoot and roots showed no reduction, except in the case of Succinic acid at
-1M, with 100% reduction in root production and 80% reduction in shoot development compared to
non-treated control. No reduction was observed at -2M (Table 36).
Pre and postemergence greenhouse assays have been completed on all of the compounds. None o f the
compounds tested showed any significant decrease in stand compared to the non-treated controls in
preemergence assays (Table 37 & 38). Postemergence applications had only one treatment that
showed any effect. Catechol at -1M caused tip burning, but the seedlings fully recovered in about two
weeks. All compounds were tested at the lowest dilution.

Conclusions
While most o f these compounds were quite effective at inhibiting germination at the -1M
concentration and a seemingly small inhibition at -2M and -3M the extent to which they retard shoot
and root formation should affect a seedlings ability to survive once it has germinated.
Any o f the compounds that show promise will be tested against other turf weed species. Phytotoxicity
studies will be conducted on mature desired turf species to determine if the dose levels that show
allelopathic activity on seedling germination have any deleterious effects on these species.

62

Table 35. Summary o f germination inhibition from petri dish assay.

Treatment

% Germination

% Visual Reduction

Tannic Acid -1M

0

100% root 100% shoot

Tannic Acid -2M

83

80% root 30% shoot

Tannic Acid -3M

100

50% root > 5% shoot

Arbutin -1M

25

100% root 50% shoot

Arbutin -2M

100

90% root 30% shoot

Arbutin -3M

98

> 5% root and shoot

Catechol -1M

0

100% root 100% shoot

Catechol -2M

78

80% root 80% shoot

Catechol -3M

98

20% root > 5% shoot

Table 36. Summary of germination inhibition from petri dish assay.
Treatment

% Germination

% Visual Reduction

Aloin -3M

100

0

Aloin -4M

100

0

Esculin -3M

100
100

0

Gramine -2M

100

0

Gramine -3M

100

0

Succinic acid -IM

37.5

100% root 80% shoot

Esculin -4M

0

Succinic acid -2M

100

0

Syringic acid -3M

100

0

Syringic acid -4M

100

0

Table 37. Comparison of mean stand count for first run of preemergence applications.
Treatment

Mean Stand Count

Control

144

Arbutin

143

Pyrocatechol (catechol)

141

Tannic acid
LSD(ao5)

140
4.76

63

Table 38. Comparison o f mean stand count for preemergence applications, on second set o f compounds.

Treatment

Mean Stand Count

Barbaloin (Aloin) -3M

142

Syringic arid -3M
Suerinic arid -IM

141

Gramine -2M

141

Esculin -3M

141

Control

139

LSD(0t05)

7.01

141

64

Fertilizer Trials and
Soil Studies

Natural Organic Source Study
M. L. Agnew

The objective of this study is evaluate the effects of different natural organic nitrogen sources on
Kentucky bluegrass growth.
Treatments included 6 natural organic nitrogen sources and a non-fertilized control. Nitrogen sources
include: blood meal, com gluten meal, leather meal, composted turkey manure, composted chicken
manure, and activated sewage sludge. Applications of 1 lb N were made on May 27, July 1, and
August 15, 1993. Treatments were made on newly established ’Bronco’ Kentucky bluegrass mowed at
2 inches and irrigated to prevent drought.
Plots were rated for quality in June, July, August, and September. Visual quality is measured on a
scale of 9 to 1: 9 = best quality, 6 = acceptable quality, and 1 = poorest quality. Clippings were
collected from a 2 ft X 5 ft area in June, July, August, September, and October. Clippings were oven
dried, weighed and reported as grams of dried tissue per 10 ft2. Roots were collected in November of
1993. These were segmented into 4 depths, washed and oven dried, then reported as grams o f root
tissue per depth.
Composted chicken manure produced the best quality turf followed by composted turkey manure, corn
gluten meal, and blood meal (Table 39).
Composted chicken manure produced over 100% more clippings than any other nitrogen source (Table
40), while it produced the least amount of roots (Table 41). The free ammonia in chicken manure
obviously benefitted shoot growth, however, it was also aided record rainfalls that negated any
potential ammonia toxicity. This was noted in previous natural organic nitrogen trials.
This study will be repeated in 1994 to validate the data.

65

h i'' t''

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15.8
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2.7

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4.4

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4.0

Total

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rH

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66

D
X
G
b

£
i
co
S«

U
3
§
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«
a>
jsi
I

ooo
.2s
X

a s
o _e a>
2H
g s 1 -b
I
S 8 2 ß o #
•a

Control (0)

G

3
5

4.0

X
X

4.8

a

1.8

rH

rH
rH

1.5

x
x

X O m O) q
(N K K x in
VO d

rH

m rt

rH

1.7

<
L>
C
3

X X r* r- Ov VO ^t x

cC
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LSD(o.oî)__________________ 4^9_______ 2.5

o

in

h Tt

X q
n-

1.3

a

Ö0
c
*S<
a.

1.3

r5 00 Is 'O Is

m

2.0

r- x

27

cv x

30

Table 39. The influence of organic nitrogen source on turfgrass quality.

P

T able 4 1 . T he in flu en ce o f organic nitrogen source on turfgrass rooting.

Depth (cm)
Fertilizer Source

0 -5

5-10

10-15

15-20

Total

Blood Meal

47.5

22.7

14.2

7.7

92.2

Com Gluten Meal

67.7

20.9

12.5

7.7

108.9

Leather Meal

49.3

25.2

14.3

9.2

98.0

Turkey Manure

70.8

21.6

16.4

9.4

118.2

Chicken Manure

46.6

20.5

13.4

6.9

87.4

Sewage Sludge

74.5

26.5

16.4

6.6

123.9

Control

70.2

24.6

14.0

8.0

116.8

LSD(0.05)

21.9

NS

NS

NS

NS

67

Fertilizer Rate Evaluation
M. L. Agnew

This study was established in Spring, 1993, to compare the effects of seven different nitrogen
formulations on a nine-year-old stand of ’Ram I’ Kentucky bluegrass. Individual plots measured 3 ft x
10 ft and the treatments were replicated three times in a randomized block design. The plots were
mowed weekly, collecting all leaf tissue above 2 ft, with one mower pass. Irrigation was added to
reduce plant stress.
Nitrogen fertilizers used in this study include: Nutralene, SCU, Coron, Urea, Nutralene + Urea, SCU
+ Urea, and Coron + Urea. The fertilizers were applied at 3 rates on May 10, June 26, and August
14.
Data collected included fresh visual quality ratings, clipping weights, and root density. Visual quality
ratings were collected weekly prior to clipping removal. Ratings are based on a scale o f 9 to 1: 9 =
dark-green turfgrass stand, 6 = minimum acceptable quality, and 1 = dead, straw-brown turf.
Clippings were collected each week or when enough growth warranted clipping removal. Clippings
were collected with a Toro rotary mower and placed in bags. Clippings were dried and the weights
were recorded. In November, roots were collected, washed, oven dried and recorded as mg of dry
tissue.
Visual quality ratings are shown in Figure 6. For the 0.5 lb N rate SCU and Coron + Urea had the
highest overall quality. For the 0.75 lb N rate Nutralene, SCU, Urea, and Coron + Urea had the
highest overall quality. For the 1.0 lb N rate Urea, Nutralene, Nutralene + Urea, and SCU + Urea had
the highest overall quality.
Clipping weight data is shown in Figure 7. In general for all rates, Urea treated plots produced the
greatest amount of clippings. This was followed by SCU treated plots.
Rooting data is presented in Figure 8. For the 0.5 and 0.75 lb N rates, Coron and Coron + Urea
treated plots had the greatest amount of roots. At the 1.0 lb N rate the Urea treated plots had
significantly less roots than SCU, Coron, SCU + Urea, and Coron + Urea treated plots.

68

N itrogen Source
0.5 N/M Rate
Visual Quality

Figure 6.

----------------------------------------------------------------V isual Q uality

8

N u trala n a

6CU
CORON
U raa
N utralana ♦ U
SCU ♦ Uraa
CORON ♦ Uw

Nitrogen Source
0.75 N/M Rate
Visual Quality
V isual Quality

Nitrogen Source
1.0 N/M Rate
Visual Quality
Visual Q uality

5.3
5 .7
6 .7

N u trala n a
SCU
CORON

6.3
5

Nutralana ■*. Uraa
SCU a Uraa
CORON » U raa

CI

6
6 .7

7.3
8
6.3

7.3
7.3
6 .7

8

8

7 .7
8
6.7

7.3
7 .7
7

7 .7
7
5.7
6.3
6 .7
7
7

4 .3
3 .7
5
5.3
4.3
5
5.3

6 .7
4 .7
6 .7
6
6.3
6
7

69

7
6
6 .7
6.7

7.3
7
5.7
6

7.3
6.7
7

7.3
7.3
7

7 .3
7
6 .3
7 .3
7

7.7
8
7
8
7.7

7
7

7.3
7.3

7
7 .3
6 .3
8.3
8 .3
7.3
6

6.8
6 .5
6.3
6.8
6 .8
6.8
6.7

N itrogen S o u rc e
Figure 7.

0.5 N/M Rate
Clipping Weights

----------- —

-----------------------------------------------

g ra m s dry w eight

Nitrogen Source
0.75 N/M Rate
Clipping Weights
g ram s dry w eight

43.4
4 0 .8
4 6 .9

N utr*l*n*
El
SCU
Ur**
Nutr*l*n* ♦ Ur** B
SCU « Ur**
■
Coron
COROW ♦ Ur*«

ÜI

28.3
3 3 .2
2 9 .2

4 7 .5
41.1
3 8 .6
4 6 .4

1 8.3
1 8 .9
16.3
1 5 .8
1 7.4
18.3
1 7 .5

2 3 .6
2 5 .2
2 1 .9
21.3
24
24.1
2 3.3

20.3
21.3
5.7
15 .8
17.8
19.9

11.8
1 1 .9
12.2
12.8
12.6

20.2

24.4
2 0 .7
3 1 .7
23 .7
25 .2
29.1
3 1 .9

1 9 .9
1 8 .2
29.4

28.8
28.8
29.3

22.2
18.4

22.1
26 .7
2 7 .5
25.8

20.8

17.4
18 .8
19
14.4
1 5 .6

20.9
20.3
1 7 .7
1 7 .2

17.3
1 6 .5

18.3
16 .2

1 9 .9
2 0 .7
18 .6
18 .9
1 9 .2
1 7 .8
1 9 .7

23
23.4
20 .5
21.1

19.1

2 7 .5
2 5 .9
2 7 .6
2 7 .6
2 8 .6
20.8
22.6

Nitrogen Source
1.00
N/M Rate
Clipping Weights
g ra m s dry w eight

62

52

42

32

22

12

N utr*l*n*
SCU
Ur**
NuVftlcn* ♦ Ur**
SCU + Ur**
Coron
CORON * Ur**

u
B
B

B
B
B

Ü

4 3 .6
4 3 .6
4 9 .9
4 5 .9
52.1
6 0 .7
5 4 .3

3 0 .3
31.1
3 7 .7
39.1

1 8 .5
1 7 .6
22.3
2 3 .4

33.1
2 9.7
3 0 .9

1 8 .2
1 7 .5

19.3

2 5 .2
2 5 .2
2 8 .7
3 0 .4
2 3 .7
2 3 .7
24.4

18.6
17.3
2 5 .9
2 4 .2
1 6 .9
16
1 8 .6

8.1
6 .8
6 .5
9.1
7.3
6.2
7.1

12.3
11 .6
1 3 .9
14.4
1 3 .2
10.4
13

70

3 4 .7

3 5 .8
3 2 .3

2 7 .9
1 9 .7
3 4 .6
3 4 .6
30.1

3 1 .3
4 1 .4

2 8 .2
3 5 .3

30
3 0 .5

3 0 .6
22
36.1

2 8 .9
34 .4
3 1 .3
3 1 .8

20.3
19.2
21.1

3 2 .2
3 3 .3
3 6 .2
3 6 .2
31.1
2 2 .6
2 9 .7

N itro gen S o u rce
0.5 N/M Rate
Root Density
F igure 8 .
m g dry roots

Nitrogen Source
0.75 N/M Rate
Root Density
m g dry roots

402

302

202

102

Nutralana
SCU
CORON
Uraa
Nutralan» ♦ Ur»«
SCU ♦ Uraa
CORON « U n a

_

Fl

155
1 5 8 .0
1 3 2 .6
2 1 7 .5
2 3 5 .6

35
53.1
44.9

2 4 1 .2
2 8 6 .2

5 3 .8
7 7 .9

4 3 .9
58 7

20.1
22.4
17
21.3
2 2 .9
27
2 4 .2

9.4
10
7
11.1
14.7
9 .5

21 7.1
2 4 1.2
204.4
2 8 9.6
32 8.4
3 3 6 .7
3 9 7 .8

Nitrogen Source
1.00 N/M Rate
Root Density
m g dry roots

352
302
252
202
152

102
52

2
N u iraie n t
SCU
CORON

B

m
■

Nutralana * Urta
SCU * Urea

■

s

1 7 9 .2
247 .4
1 9 2 .6
1 2 0 .2
1 5 1 .5

3 9 .6
57
56
4 5.4
41.1

16.3
3 4 .2
2 3 .9
1 4 .7
14 .6

200.6

4 8 .5
5 5 .9

20 .9
17.4

202.8

71

7.4
1 3 .3
12
6 .7
10.6
10.8
10.6

242.5
3 5 1 .9
2 8 4.5
187.1
21 7 .8
28 0 .7
286.8

UHS Controlled Release Nitrogen Study
M. L. Agnew

The objective of this study was to evaluate two UHS polymer coated ureas in field situations.
This site was located at the Iowa State University Research Station north of Ames, Iowa. The soil
type is Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll). The turfgrass is a 9-year-old stand of
’Glade’ Kentucky bluegrass. The turf was mowed at 2 inches and irrigated to prevent moisture stress.
The treatments include four nitrogen sources and 2 nitrogen rates.
Trt #
1
2
3
4
5
6
7
8
9

N Source
urea
UHS2002
UHS2003
ureaform
urea
UHS2002
UHS2003
ureaform
control

Total N/Plot
4
4
4
4
3
3
3
3
0

N/ADDlication
1.33
1.33
1.33
1.33
1.00
1.00
1.00
1.00
0.00

Treatments were arranged in a randomized complete block design with 3 replications. Individual
treatment plots measured 5 ft x 10 ft.
Plots were rated for quality in May, June, July, August, and September. Visual quality is measured on
aa scale of 9 to 1: 9 = lush green turf, 6 = the minimum acceptable level, and 1 = brown turf.
Clippings were collected from a 2 ft x 5 ft area in May, June, July, August, and September. Clippings
were oven dried, weighed and reported as grams of dried tissue per 10 ft2.
Visual quality data is listed in Table 42. Nitrogen sources applied at the 1.33 lb N/1000 ft2 rate
continually had better quality ratings. In addition, urea treated plots had better quality rating following
application, whereas the UHS experimental products exhibited better quality than urea by 4 weeks
after application.
Clipping yield data is listed in Table 43. Nitrogen sources applied at the 1.33 lb N/1000 ft2 rate
produced greater clippings. Urea treated plots produced the greatest amount of total clippings.

72

2
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vo
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ri­ rt VO CS
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73

48.2

53.3
43.7

44.2

1 1

X

X

X

X

O

O

6.7

31.4

53.5
41.6
48.2

40.1

59.1

51.5

56.5
45.4

45.8
48.6

53.0

51.6

40.5

46.4

CS CO

Control

X
D

cs CO

Ureaform

(Zi

.s
è
=3
CO

Ureaforra
Urea

X

X
X
CO

X
d
CO

H
<D
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co rf rt rf rf CO CO CO CO ©
E
ffî
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b

Table 43

§
X
D

a

CO
XJ
2
U

2
Ureaforrr

o

X

X
D

CO

Urea

X

Ureaforrr

Urea

CO

§ 1
(Z)

o

Ov CO CS Ov CO X © CS vq
CO rf
io
rf rH o* rH vo
rf ? rt $ rf rf v
rt CO

63.4

0.3

7.0

7.0

7.0

8.0

0*9

03 rf rt rt rt CO CO CO CO
« a:
Un

»o X
© X
rH rH VO vo
CS CS rH

a a s

VO

51.2

.

rH

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©

CO Ov Ov
CO* rt
H d
rH1 rH
CS

»O

51.9

6.3

a

6/3

NS

7.3

tH

S

Ov CO © rf
CS
X
CS CS CS rH
rH

H
»o vo
Ov r-î rH
CS CS CS

©
»O r- CS
i-H d
cî
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a

5/26

5.7
6.7
7.3

7.3

7.3

7.7

8.3
7.3

od

7.3

7.3
7.7
7.3

8.7
8.3
7.3

6.7

7.0

7.0

L L

o
00

o

oô

6*0

O

od

Ov rt ©
CS
8 CS a

s

Ov
ç
VO

5/20

8.3

9.0

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8.3

tH
i-H

©
CO

SN

o o r- CO r- o CO o
00 00 VO s
od S VO

od

CO r* X vo VO VO X
VO VO
d
rH r-l od a VO
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a

99

6*0

K

X

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7.7

8.0

o

8.0

8.7

8.0

8.3

7/23

o

od 00 od

L L

o

00

H
jj

Fertilizer
Source

rf
X

40.5

5.7
6.3

X
d

vq o rH CS r** CS © rt
X
1—H d Ov d K rH CS d rH
CS CS CS CS rH CS CS rH rH CS

44.2

7.0

7.0
8.7

6.7

6.7

o

7.3

7.3

8.3

8.3

7.3

7.3

CO VO
VO* O

X
d

L L

7/12

r- o o
d 00 d

L L

6/15

K

rH
tH

L L

6/11

K

x

06

5/28

K

CO
rH
\
X

X

VO

Table 42. UHS visual quality data 1993.

o

od od

O
00

0*9

S

o

X

L L

d

CO CO rt
VO VO VO rt rH

UHS 200

o

o

X

o

CS rf rf rt VO
rH
X
£ S X ?

É

46.5

O

8.0

o

8.7

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The objective of this study was to evaluate three formulations o f resin-coated nitrogen sources and
sulfur-coated urea for the O. M. Scotts Company. The resin-coated fertilizer ratios were 40-0-0,
39-0-0, and 38-0-0. Each were applied at a 2 lb N application rate on May 8 and August 6 and a 1 lb
N application rate on May 8, June 29, August 6 and September 15, 1993. A non-fertilized control was
added for comparison purpose. The turfgrass was "Envy" perennial ryegrass mowed at 1-inch with all
clippings removed. The site was irrigated to prevent moisture stress.
The 1993 growing season began with the site being injured by desication. Plots were removed by
mid-June.
Data collected included visual quality and clipping yields. Visual quality is based on a scale of 9 to 1:
9 = dark green turfgrass, 6 = minimum quality, and 1 = straw-colored turf. Clipping yields were
obtained at each mowing by collecting all leaf tissue over 2-inch with a 1.75 ft x 10 ft (17.5 ft2) area.
Qippings were dried at 65°F for 48 hours and weights recorded.
Visual quality data is presented in Table 44. Generally, the 2 lb N rate provided superior quality.
However, no fertilizer rate had an unacceptable quality. There were no differences between fertilizer
source for either the 1 or 2 lb N rates.
Clipping yield data is presented in Table 45. Applying fertilizers at a 2 lb N rate substantially
increased the amount of clippings that were produced. This was most evident just after the May and
August application dates. The 40-0-0 produced the greatest amount of clippings for the 2 lb N rate,
while 38-0-0 produced the greatest amount of clippings for the 1 lb N rate.

74

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Plant Response to Nitrogen Source
M. L. Agnew

The objective of this study is evaluate the effects of eight different nitrogen sources on Kentucky
bluegrass growth.
Treatments included 2 natural organic nitrogen sources, six synthetic nitrogen sources, and a nonfertilized control. Nitrogen sources includes: Coron (28-0-0), Nutralene (40-0-0), Sulfur-Coated Urea
(37-0-0), Urea (46-0-0), Ureaform (38-0-0), N-Sure (28-0-0), Ringer’s Lawn Restore (10-2-6), and
Cbm Gluten Meal (10-0-0). Applications at 1 lb N were made on May 10, June 4, August 15, and
September 15, 1993. Treatments were made on ’Glade’ Kentucky bluegrass. This was the third and
final year of this research project.
Plots were rated for quality in May, June, July, August, September and October. Visual quality is
measured on a scale of 9 to 1: 9 = dark green turf, 6 = minimum acceptable level 1 = straw-colored
turf. Clippings were collected from a 2 ft x 10 ft area in June, July, August, and September.
Clippings were oven dried, weighed and reported as grams of dried tissue per 20 ft2.
Nutralene, Sulfur-Coated Urea, and Urea had the best overall quality, while there was very little
difference in quality of the other treatments (Table 46). This is not surprising, since the plots received
60+ inches of rainfall in 1993.
Sulfur-Coated Urea and Urea produced the greatest amount of clippings. Ureaform, Coron, and NSure produced significantly less clippings while maintaining an acceptable quality level (Table 47).
Roots were collected in April and November. Coron and Ureaform had the greatest amount of roots
following a winter that exhibited much winter injury in Iowa (Table 48). There was no difference in
root growth following the extremely wet summer (Table 49).

77

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The Effects of Soil Compaction on Soil Physical Properties
and Plant Growth of Five Cultivars of Tall Fescue
D. L. Anderson and M. L. Agnew

The selection o f a turfgrass species for use in an athletic facility is based upon tolerance o f traffic,
cold temperature stress, and irrigation requirements. Due to its tolerance of drought and wear stresses,
tall fescue makes an excellent turf for low maintenance athletic fields in southern Iowa. In a
comparison study, tall fescue was found to have a higher wear tolerance than Kentucky bluegrass
(KBG) and perennial ryegrass (PR), but its tolerance of compaction was inferior to both Kentucky
bluegrass and perennial rye. This study used improved turf-type cultivars of both KBG and PR while
using K 31 tall fescue, a grass which is more like a forage type fescue.
The objective of this study was to compare the compaction tolerances of four improved, turf type
cultivars of tall fescue with that of K 31.
On May 3, 1992, the cultivars K 31, Crossfire, Twilight, Rebel II, and Rebel Jr. were seeded at the
Iowa State University Research Station north of Ames, Iowa, at a rate of 6 lbs/1000 ft2. Three
replicated plots of each cultivar, measuring 20 ft x 15 ft, were created in a randomized block design.
Each plot was divided into six treatment plots measuring 10 ft x 2 ft, three o f which were compacted
in the fall o f 1992 and three in the summer of 1993 using a smooth power roller. Three levels of
compaction were applied: OX, 10X, and 20X, where IX equals 1 pass with the roller at 0.193 MPa.
Fall treatments were applied once per week over a 4 week period beginning August 31. The summer
compaction treatments were applied as OX, 20X, and 40X on June 23 and 30, and OX, 10X, and 20X
on August 12. The site was irrigated with an inch of water 24 hours prior to treatments to achieve
maximum soil compaction.
The plots were irrigated using athletic field type sprinkler heads at a rate of 1-inch per week to prevent
moisture stress. Fertilization was applied at a rate of 1 lb N/1000 ft2 in May, August, and September.
The grass was maintained at a mowing height of 2 inches. Herbicides were applied as needed to
control weeds.
The data collected included rooting density, dried clipping weight, visual quality, bulk density and
water retention. Visual quality was based on a scale from 9 to 1: 9 = thick, dark green turf, 6 =
minimum acceptable level, and 1 = dead turf.
The cultivars did not differ in their response to compaction (Tables 50-53). All of the cultivars
reacted to increasing soil compaction with a reduction in visual quality, clipping weights, and rooting
density. Differences were observed between the cultivars. Regardless of the compaction treatments,
Rebel Jr. consistently performed the best visually, followed by Crossfire, Twilight, and Rebel II. K 31
performed poorly, never surpassing the acceptable quality rating of 6.
Differences were also observed in the soil physical properties between the fall and summer compaction
treatments. Compaction in the fall of 1992 resulted in an increased bulk density from a control of
1.31 to 1.41 under 10X, and 1.42 under 20X treatments. Aeration porosities were reduced due to
increased soil compaction. The summer treatments resulted in no significant difference between the
bulk densities or the aeration porosities of the three treatments. This is believed to be due to the
excessive rainfall received last year saturating the soil, preventing any soil compaction from taking
place.

80

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Environmental
Research

Fate o f Nitrogen, Phosphorus, Pendimethalin, Chlorpyrifos,
Isazofos, Metalaxyl, Dicamba,
and MCPP Applied to
Turfgrass Maintained in Golf Course Fairway Condition
S. K. Starrett, N. E. Christians, and T. A. Austin

Current public concern for the environment has focused attention on the environmental effects of
chemical applications to turfgrass areas. Little research has been done concerning the environmental
effects o f N, P, and pesticides applied to turfgrasses. The objectives of this study were: 1) to
investigate the hydrology of undisturbed soil columns with a Kentucky bluegrass turfgrass and intact
macropores under a heavy and light irrigation regime and, 2) to measure the fate of N (using 15N as a
tracer), P, and 7 turf type pesticides. Dicamba, 2,4-D, and MCPP data is still being analyzed.
Preliminary results are: macropores transport surface-applied N through soil profiles; a heavy
irrigation increases N, pendimethalin, chlorpyrifos, isazofos, and metalaxyl transport compared with
light irrigation; volatilization of liquid urea is negligible when followed with irrigation; and irrigation
rate does not affect P transport after a 4-week period. N losses can be reduced by irrigation
management procedures. By applying light, more-frequent irrigations instead o f heavy, less-frequent
irrigations for several weeks after N application, N leaching is reduced.
Golf courses can be managed in such a way that even phosphorus, which is known to be fairly
immobile, can be moved through a 20-inch soil profile and potentially into the ground water.
However, there are management practices that the superintendent has control of that can greatly affect
the potential for movement o f fertilizers. These practices include rate of application, timing (just
before a heavy rainfall is not recommended), and particularly irrigation practices. In our study, 1-inch
irrigations vs. 0.25 inch irrigations, after a surface application of nitrogen, increased the amount of
nitrogen that leached 20 inches into the soil profile by 40 times.
The fate o f these pesticides were also studied under field conditions. Iowa State University and the
University of Nebraska-Lincoln conducted identical experiments over the summers of 1991 and 1992.
Preliminary results are that while the verdure (the tissue between the soil surface and the mowing
height) contained high concentrations of the pesticides immediately after application, irrigation, rainfall
and clipping reduced the amount of pesticide recovered from the plant material with time. The thatch
layer was highly retentive of the pesticide residues. Dicamba, 2,4-D, and MCPP were most mobile,
followed by metalaxyl and isazofos. Chlorpyrifos and pendimethalin were the least mobile.
Pendimethalin, chlorpyrifos, isazofos, and metalaxyl appeared to degrade more rapidly in the turfgrass
environment than typically reported for other agronomic crop systems.

83

Herbicidal Activity of Hydrolysed Corn Gluten Meal on
Three Grass Species under Controlled Environments
D. L. Liu, N. E. Christians, and J. T. Garbutt

Synthetic organic pesticides have become a major component o f agricultural, forestry, and turfgrass
management systems. Environmental and human health problems associated with pesticides have been
documented. Public awareness and concern for environmental protection and human safety has led to
the search for naturally occurring compounds that are able to inhibit growth and development o f weed
plants. Commonly-assigned U.S. Patent 5,030,268 disclosed that com gluten meal can be used as a
natural preemergence herbicide, however, it is quite insoluble in water and this characteristic renders it
hard to apply as a herbicide. The herbicidal activity of 17 samples derived from com gluten meal and
other crop materials were evaluated using 3 different grass species under controlled environments.
Based on the results from greenhouse and growth chamber bioassays, it was found that samples of
enzymatically hydrolyzed com gluten meal were more herbicidally active than the com gluten itself
and were highly water-soluble. Com gluten hydrolysate derived from the action o f bacterial proteinase
had the highest inhibitory activity. This water soluble material derived from com gluten meal had a
growth-regulating effect on the root system, therefore it can potentially be used as a natural herbicide.
A patent entitled "Preemergence Weed Control Using Plant Protein Hydrolysate" was applied for on
July 28, 1993, a notice of allowance was granted on September 28, 1993, and a patent number of
5,290,749 was issued on March 1, 1994 by U.S. Patent and Trademark Office.

84

Isolation and Identification o f Root-Inhibiting
Compounds from Corn Gluten Hydrolysate
D. L. Liu and N. E. Christians

Since pesticides are toxic or biologically active by design, there is a concern regarding their effects on
human health and environmental quality. Interest has centered on the use o f plant derived compounds
as natural herbicides and they are considered to represent an environmentally sound approach to weed
control. Com gluten hydrolysate found to have a growth-regulating effect on the root system of
germinating grass seeds has been suggested to be used as a natural herbicide. If the bioactive
compounds in com gluten hydrolysate can be isolated and identified, they could be used as natural
herbicide to serve as a starting point for chemical synthesis of biodegradable herbicides. The objective
of this study was to develop a protocol to extract, isolate, and identify the root-inhibiting compounds
from com gluten hydrolysate. An aqueous solution of com gluten hydrolysate was used for isolation
o f root-inhibiting compounds from Zea mays L. and a perennial ryegrass bioassay was developed to
test the root-inhibiting activity. Five bioactive dipeptides were isolated by using Sephadex G-15 gel
filtration, solid phase extraction, and C18 reversed-phase high performance liquid chromatography
procedures. The five dipeptides were glutaminyl-glutamine, alaninyl-asparagine, alaninyl-glutamine,
glycinyl-alanine, and alaninyl-alanine. Their root-inhibiting activity on perennial ryegrass was
demonstrated in petri dish bioassays. They could be used as a substitute for synthetic chemical
herbicides or as a supplement to synthetic herbicides to reduce the concentration of these pesticides in
the environment. A patent entitled "Preemergence Weed Control Using Peptides Isolated from Com
Gluten Hydrolysate" was applied for on July 28, 1993, a notice of allowance was granted on October
1, 1993, and a patent number o f 5,290,757 was issued on March 1, 1994 by U.S. Patent and
Trademark Office.

85

Evaluation of Corn Gluten Meal as a
Natural Weed Control Product Under Greenhouse Conditions
B. R. Bingaman and N. E. Christians
Recent research has shown that the protein fraction of com grain extracted in the wet-milling process,
com gluten meal, can be effective in controlling several monocotyledonous and dicotyledonous weed
species and has the potential for use as a natural product herbicide in both turfgrass (Christians, 1993)
and strawberry ecosystems (Nonnecke and Christians, 1993). Root formation during germination is
inhibited by com gluten meal in susceptible species. When the affected plants are then submitted to
moisture stress, mortality results because of the poorly developed root systems (Christians, 1993). In
addition, com gluten meal is approximately 10% nitrogen by weight and provides an additional
nitrogen source to plant species with well developed root systems. United States Patent Number
5,030,268 has been granted for the use of com gluten meal as a surface applied preemergence
herbicide.

Twenty-two plant species were screened for susceptibility to com gluten meal under greenhouse
conditions. Ten dicotyledonous species were used: velvetleaf (
tkeophrasti Medic.), redroot
pigweed (Amaranthus retroflexus L.), lambsquarters (
album L.), catchweed bedstraw
(<Galium aparine L.), black medic (
Medicagolupulina L.), buckhom plantain (
lan
purslane (
P
ortu
laco lerácea L.), curly dock (
Rumexcrispus L.), black nigh
L.), and dandelion (
Taraxacumofficinale Weber). Eleven monocotyledonous species were scr
quackgrass
(Agropyronrepens (L.) Beauv.), orchardgrass (Dactylis glomerta L.), smooth crabgrass
(Digitaria ischaemum (Schreb.) Schreb. ex Muhl), large crabgrass (
sanguinalis (L.) Scop.),
bamyardgrass (
Echinochloacrus-galli (L.) Beauv.), woolly cupgrass (
villosa (Thunb.)
Kunth), annual bluegrass (Poa annua L.), giant foxtail (
faberi Herrm.), yellow foxtail (
lutescens (Weigel) Hubb.), green foxtail (
etariviridis (L.) Beauv.), shattercan
S
L.), and creeping bentgrass (
Agrostispalustris Huds.).
Com gluten meal was applied at 0.0, 30.2, 60.4, and 90.5 g ft'2. The treatments were applied to the
soil surface for the preemergence (PRE) treatments and were mixed with the top 2.5 cm o f soil for the
preplant incorporated (PPI) treatments.
Treatment with com gluten meal reduced the survival rates of all broadleaf and grass species tested
(Table 54). The results of these greenhouse screenings substantiate the preliminary observations from
previous studies that the efficacy of com gluten meal may extend to a broad spectrum of
monocotyledonous and dicotyledonous plant species (Christians, 1993). All tested broadleaf and grass
species exhibited some degree of susceptibility to the herbicidal properties of com gluten meal.
More field trials are necessary to confirm the efficacy of com gluten meal for specific problem weed
species. Additional work is being conducted to determine the optimum treatment levels and
application methods necessary to provide satisfactory weed control in different management systems.

86

Table 54. Reductions in the Survival o f Plants Treated with Three Levels o f Com Gluten M eal”

% Reduction in Plant Survival
Plant Species

60.4 g ft'2

30.2 g ft'2

90.5 g ff2

annual bluegrass

60

81

72

bamyardgrass

31

35

41

black medic

49

63

63

black nightshade

78

99

100

buckhom plantain

80

95

96

catchweed bedstraw

66

33

94

common lambsquarters

82

88

99

creeping bentgrass
curly dock

85

85

96

75

94

97

dandelion

42

90

100

giant foxtail

63

54

83

green foxtail

37
51

78
70

100

large crabgrass
orchardgrass

56

53

92

purslane

97

95

100

quackgrass

0
87

20

71

96

99

shattercane

42

43

51

smooth crabgrass

51

85

97

velvetleaf

0

18

35

redroot pigweed

82

woolly cupgrass

6

29

79

yellow foxtail

43

65

78

■LSD(aoS) = 40 for mean comparisons among com gluten meal treatment levels for each species.
bThese data are mean percentages of the plant survival reductions as compared with the survival of the control plants. These
reductions are the means for surface applied (PRE) and preplant incorporated (PPI) treatments (n=12 for each treatment).

REFERENCES
Christians, N. E. 1993. The use of com gluten meal as a natural preemergence weed control in turf.
In "International Turfgrass Society Research Journal" (R. N. Carrow, N. E. Christians, and R.
C. Sherman Eds.), pp. 284-290. Intertec Publishing Corp., Overland Park, Kansas.
Nonnecke, G. R;, and Christians, N. E. 1993. Evaluation of com gluten meal as a natural, weed
control product in strawberry. Acta Horticulturae 348, 315-320.

87

A Study on the Effects of Corn Gluten Meal
and Corn Gluten Hydrolysate on the Establishment o f
Agrostis Palustris
J. A. Livingston and N. E. Christians
The purpose o f this study was to test the inhibitory effects of different rates of com gluten meal and
gluten hydrolysate on the seed germination of creeping bentgrass (Agrostis palustris').
"Com gluten meal is a 60% com protein material that is produced in the wet-milling process." It
contains about 10% nitrogen (N) by weight and has been used as a feed material for many different
animals. Although normally produced as a powder, com gluten meal can be made in pellet form for
easy application. Com gluten meal is not very water soluble (Table 55).
Research by Dr. Nick Christians led to the eventual patent of com gluten meal as a preemergence
weed control in 1991. The com gluten meal was found to inhibit root formation of germinating seed,
which is detrimental to the plant when water is withheld from it. Further research has shown that
when used on established turf, com gluten meal is an excellent natural fertilizer (Table 55).
Gluten hydrolysate, a water soluble extract of com gluten meal, also has comparable preemergence
control capabilities to com gluten meal. One advantage of gluten hydrolysate is that it can be used as
a liquid spray. A patent was also issued in 1993 for the use of the hydrolysate as a natural herbicide
(Table 6).
The objective of this experiment was to do a comparison of com gluten meal and gluten hydrolysate.
The study will help to determine which rates of material provide the most effective inhibition o f
germinating seed.
The experiment was started on March 10, 1994. Eighty-four 3x3 in2 pots were filled with sifted soil
from the greenhouse. The creeping bentgrass was applied to the pots at a rate of 5g/10,000 cm2 (0.029
g/pot). After the seed was applied, seven rates of com gluten meal and gluten hydrolysate were added
to the pots. The materials were applied at the following rates: 0, 0.2, 0.5, 2.0, 6.0, 8.0, 10.0 g/dm2,
(0, 0.12, 0.29, 1.16, 3.48, 4.65, and 5.81 g/pot). Each treatment was replicated three times.
Two watering methods were used in the experiment. Twenty-one pots with each of the seven com
gluten meal treatments were placed on a greenhouse mist bench, while the other twenty-one com
gluten meal treated pots were wetted and then wrapped in parafilm. The same was done to the
hydrolysate treatments.
After the seeds started to germinate, the pots on the mist bench were moved to a greenhouse bench
where they were watered every two to three days. The parafilm covered pots were opened at night to
prevent mold from growing and covered again during the day to prevent drying.
Six days after the beginning of the experiment, all pots were surface watered using a watering can.
The next day the parafilm treatments were placed in a plastic flat which was half filled with water.
The parafilm treatments were removed from the flat two days later. For the remainder o f the
experiment, all pots were kept quite dry and were watered lightly only when needed. Photographs and
visual data were taken towards the end of the experiment.

88

Visual data showing percentage (%) cover of the treated pots compared to the control was taken after
twenty and twenty-six days respectively. After twenty days, the surface watered hydrolysate
treatments showed the greatest amount of inhibition on the creeping bentgrass. The surface watered
com gluten meal treatments had the least effect on the germinating seed. Subsurface watering had
greater inhibition on the com gluten meal treated pots; however, surface watering provided greater
inhibition on the hydrolysate treated pots. The hydrolysate treatments showed the most overall control
on the germinating creeping bentgrass. The data after twenty-six days also gave results similar to the
twenty day data. The visual data for both dates is summarized in Tables 55 and 56.
A very wide range of rates was used in this experiment. No seed germination occurred at rates equal
to or greater than 6.0 g/dm2. Therefore, more experimentation will be conducted to determine the
amount o f inhibition that can be expected at lower rates of application. New experiments will be
conducted with the same procedure with a smaller range of rates.
Table 55. Percentage o f cover (%) 20 days.
Com Gluten Meal

Hydrolysate

Surface
Watered

Subsurface
Watered

Surface
Watered

Subsurface Watered

Control

100

100

100

100

0.2

95

78

32

92

0.5

37

72

5

25

2.0

Treatment
g/dm2

5

2

0.3

6.0

0

0

0

0.3
0

8.0

0

0

0

0

10.0

0

0

0

0

3.8

3.2

2.0

1.9

Table 56. Percentage of cover (%) 26 days.
Hydrolysate

Com Gluten Meal
Surface
Watered

Subsurface
Watered

Surface
Watered

Subsurface
Watered

Control

100

100

100

100

0.2

90

55

28

98

0.5

60

45

0.7

22

2.0

5.0

0.3

0.3

0

6.0

0

0

0

0

8.0

0

0

0

0

10.0

0

0

0

0

11.5

6.6

1.9

1.9

Treatment
g/dm2

LSD((X05)

REFERENCES
Christians, N.E. 1993. The use of com gluten meal as a natural preemergence control in turf. Inter.
Turfgrass Soc. Res. J.7, R.N. Carrow, N.E. Christians, R.C. Shearman (Eds.) Intertec
Publishing Corp., Overland Park, KS. pp. 284-290.
Christians, N.E., D.L. Liu, and J.T. Garbutt. 1993. Preemergence weed control using plant protein
hydrolysate. U.S. Patent issued in Oct. 1993, patent number to be issued in March of 1994.
89

Innovative Production Techniques for Shade and Ornamental Trees
J. K. lies

Introduction
Producing landscape plants in containers has become a permanent and important part of the nursery
industry. In some parts of the country, container culture has replaced field culture as the primary
method of production. Still, production costs for container-grown ornamentals can be quite high
prompting nursery managers to grow only plants that perform reliably in containers and reach
marketable size quickly. Since the early 1980’s, several in-ground container production systems have
been developed to overcome three serious problems associated with traditional container-growing
methods: root circling in the container; plant stability; and low-temperature injury to roots.
Trees produced using in-ground containers will not blow over, can be overwintered in place, are
protected from harmful high root zone temperatures during the summer, require less water than above­
ground culture, and are far easier to transplant than traditional field-grown stock.

Pot-in-pot - The innovative pot-in-pot system involves sinking an outer sleeve pot into the ground,
and inserting a second pot, the actual production pot that is harvested with the tree, inside the sleeve
pot. The production container often has vertical basal ribs, or may be copper-treated to reduce root
circling.
In-ground plastic containers - In the past, trees could not be grown in-ground using single plastic
containers because of drainage problems. Recently, a rigid plastic container has been developed which
has rows of small holes around the container sides and throughout the container base. The many
perforations should help moisture drain from the container and reduce the potential for circling roots,
however, no comparative tests have yet been conducted.
In-ground container culture will help reduce root zone temperature and moisture extremes, but will the
improved container/media environment result in accelerated growth for nursery stock? Treeshelters
(cylindrical polypropylene tubes) have been broadly used in Great Britain to reduce costs o f
establishing small forest and landscape trees. Treeshelters protect young trees against herbicidal drift
and animal browsing, but their most noteworthy benefit is the 60 to 600% increase in plant growth
that results from their use. Elevated temperature, humidity, and/or carbon dioxide concentration within
treeshelters have all been suggested as probable causes for the increased growth. But the advantages
of using treeshelters in container culture has not been fully explored.
Therefore we have initiated a study to: (1) determine how several tree species would respond to being
grown in in-ground plastic containers with and without treeshelters, and (2) compare their growth with
growth and survival of trees grown using traditional field production techniques.

Materials and Methods
In spring 1994, seedlings (18-24 inch) of five tree species (Table 57) were obtained from Lawyer
Nursery, Inc. (Plains, Mont.) and randomly assigned to six nursery production treatments (Table 58).
A randomized complete block design was used. Plant height was measured at the beginning o f the
experiment, and will be measured again at the end of the first year (Sept. 1994) and at the end o f the
second year (Sept. 1995) of the study. Temperature, relative humidity, and carbon dioxide
concentration will be measured inside and outside treeshelters twice during each year of the study. At
the completion of the experiment, fresh and dry weights of shoots and roots will be obtained.

90

Table 57. Tree species used to evaluate in-ground container/treeshelter production systems.

Acer buergeranum - Trident maple
Cercidiphyllum japonicum - Katsuratree
Corylus colurna - Turkish filbert
Maackia amurensis - Amur maackia
Sorbus alnifolia - Korean mountainash

Table 58. Tree production treatments.

Control - Field-grown/no treeshelter.
Treatment 1 - Field-grown/with treeshelter.
Treatment 2 - In-ground single container.
Treatment 3 - In-ground single container/with treeshelter.
Treatment 4 - In-ground pot-in-pot.
Treatment 5 - In-ground pot-in-pot/with treeshelter.

91

Determination of the Site of Action o f a
Root Inhibiting Compound Derived from Corn Gluten Meal
J.B. Unruh and N.E. Christians

In 1985, it was observed that unprocessed com meal applied at large quantities to soil areas had an
inhibitory effect on the establishment of germinating plants. Further studies showed that the protein
fraction of com grain, com gluten meal, had higher levels of the inhibitor. The work o f D. L. Liu and
N. E. Christians, Iowa State University, subsequently led to the isolation and identification o f five root
inhibitory compounds contained in the water soluble protein extract from com gluten meal.
In an effort to better understand the efficacy of these root inhibiting compounds for weed control
purposes, investigations are currently underway to determine the site of action of these root inhibiting
compounds.
Microscopic studies focusing on cellular activity of treated and untreated plants are currently being
done. These studies are revealing structural and morphological differences between treated and
untreated seedlings, as well as differences in cell processes such as cell division.
The next major phase in this project will be to label the root inhibiting compound with a radioactive
marker, and then through special processes, trace the compound's movement through the plant. This
project should be completed within the next year.

92

The Use o f a Natural Product for the
Preemergence Control of Annual Weeds
N. E. Christians

In 1985, it was observed that unprocessed com meal applied in large quantities to soil areas had an
inhibitory effect on the establishment of germinating plants. Further evaluations showed that there was
a naturally occurring, organic compound (or compounds) within the com meal that had a growth
regulating effect on the root system of germinating plants. Studies were conducted to determine if any
o f the components o f the com meal contained higher concentrations of the inhibitory substance. It
was discovered that high levels of the inhibitor were found in the com gluten meal, the protein
fraction of the com grain.
The com gluten meal contains 10% nitrogen by weight and was shown to be a good natural source of
fertilizer nitrogen for mature plants that had well established root systems. Further studies
demonstrated that the com gluten meal could be used as a natural ’weed and feed’ material for lawn
areas. The nitrogen in the product serves as a nutrient source to improve lawn quality, while the
inhibitory substance acts to prevent germinating weeds, such as crabgrass, from infesting the lawn.
Several grassy and broadleaf weeds have been shown to be controlled by preemergence application of
the com gluten meal. United States patent 5,030,268 was issued for the use of com gluten meal as a
natural preemergence herbicide in July, 1991 and reissued with broader claims as Re. 34,594 on
April 26, 1994. A marketing agreement has been reached with Gardens Alive Corporation and
marketing should begin in late summer 1994. Marketing agreements with other companies are also
being pursued.
Com gluten meal is a byproduct of the wet-milling process. It has been used for decades as an animal
feed for dogs, poultry, fish, and many other animal species. The product is being promoted as an
environmentally safe, natural herbicide that can be used to control weeds preemergently in turf areas
without the use o f synthetic preemergence herbicides that are presently used in large quantities in the
U.S.
Work has also been conducted on other crop systems, such as strawberries, floral crops, and vegetable
crops. It anticipated that the com gluten meal will find a market for these crop systems as well as for
home gardening.
Some discussion on the registration of this material have taken place with representatives of the
Environmental Protection Agency. A package of information to initiate the registration process should
be submitted within the next few weeks.
Cbm gluten meal was applied to 5 ft x 5 ft plots at the research station during 1991, 1992, and 1993
at levels o f 0, 2, 4, 6, 8, and 10 lb N/1000 ft2 (20, 40, 60, 80, and 100 lbs com gluten meal/1000 ft2).
Data from the 1993 season on crabgrass control with com gluten meal are shown in Figure 9.
Crabgrass was reduced by 90% at the 2 lb N/1000 ft2 rate (20 lb of com gluten meal/1000 ft2).
Higher levels of control were achieved at higher rates of com gluten meal, but these rates are generally
impractical for use on turf. The control held to the end of the 1993 crabgrass season even though the
late summer o f 1993 was extremely wet.
Applications o f this same rates of com gluten meal were applied to the same plots in the spring of
1994.

93

94

LBS. N PER 1000 SQ. FT.

1993 CRABGRASS
CONTROL
TRIAL
WITH CORN GLUTEN MEAL: SEPT. 1993

Introducing

Introducing
Iowa State University Personnel
Affiliated with the Turfgrass Research Program

Michael Agnew, Ph.D.

Associate Professor, Extension Turfgrass Specialist
Horticulture Department

Dave Anderson

Graduate Student and Research Associate
Horticulture Department M.S. (Agnew, M./ Christians)

Doug Campbell

Research Associate, Horticulture Department

Nick Christians, Ph.D.

Professor, Turfgrass Science Research and Teaching
Horticulture Department

Jim Dickson

Field Manager, Horticulture Department

Steve Driscoll

Field Technician, Horticulture Department

Paula Flynn

Extension Associate, Plant Disease Clinic
Plant Pathology Department

Mark Gleason, Ph.D.

Assistant Professor, Extension Plant Pathologist
Plant Pathology Department

Mark Hartman

Field Technician, Horticulture Department

Harlene Hatterman-Valenti, Ph.D.

Extension Associate, Weed Science Department

Clinton Hodges, Ph.D.

Professor, Turfgrass Science Research and Teaching
Horticulture Department

Jessica Latta

Field Technician, Horticulture Department

Donald Lewis, Ph.D.

Associate Professor, Extension Entomologist
Entomology Department

Dianna Liu, Ph.D.

Postdoctoral Research Associate, Horticulture Department

Joe Livingston

Undergraduate Research Associate, Horticulture Department

Jason Manfull

Field Technician, Horticulture Department

Richard Moore

Interim Superintendent Horticulture Research Station

Steve Nelson

Field Technician, Horticulture Department

Glenn Pearston

Computer Consultant, Horticulture Department

Gary Peterson

Extension Field Specialist - Horticulture

95

Timothy Roethler

Undergraduate Research Associate, Horticulture Department

Marcy Simbro

Field Technician, Horticulture Department

Julie Smith

Field Technician, Horticulture Department

Steve Starrett

Graduate Student and Research Associate
Civil Engineering Department Ph.D. (Christians/Austin)

J. Bryan Unruh

Graduate Student and Research Associate
Horticulture Department Ph.D. (Christians)

We would also like to thank Adrian Lucas, William Emley, Lynn Schroeder, and A1 Morris for their
support during the last year.

96

Companies and
Organizations

Companies and Organizations That Made Donations
or Supplied Products to
the Iowa State University Turfgrass Research Program

Special thanks are expressed to the Big Bear Turf Equipment Company and Cushman Turf for providing
a Cushman Turfgrass Truckster, a mataway, a lawn aerifier, and a Jacobson Turf King reel mower for
use at the research area in 1993; to Tri-State Turf and Irrigation for providing a Greensmaster III Triplex
Greensmower for use on the research area and a Groundsmaster 220 rotary mower.

Grain Processing Corporation
PO Box 349
Muscatine, Iowa 52761

American Hoechst Corporation
Agricultural Chemicals Department
Route 1 - Box 7
Brownsdale, Minnesota 55918

Grace Sierra
PO Box 4003
Milpitas, California 95035-2003

Big Bear Turf Equipment Company
10405 T Street
Omaha, Nebraska 68127

Grass Roots Turf
6143 Southwest 63rd
Des Moines, Iowa 50321

Ciba Corporation
Agriculture Division
Greensboro, North Carolina 27049

Growth Products Inc.
PO Box 1254
White Plains, New York 10602

Coron Corporation
PO Box 198
Souderton, Pennsylvania 18964

Harmony
PO Box 846
Waterloo, Iowa 50704

Cushman Turf
5232 Cushman
Lincoln, Nebraska 68501

Iowa G olf Course Superintendents
Association

D & K Turf Products
8121 Parkview Drive
Urbandale, Iowa 50322

Iowa Professional Lawn Care
Association

DowElanco
Midland, Michigan 48674

Iowa Sports Turf Managers
Association

Earthgro
P.O. Box 143
Lebanon, Connecticut 06249

Iowa Turf Producers and
Contractors

Enviro-Gro Technologies
P.O. Box 5036
Lancaster, Pennsylvania 17601-0036

Iowa Turfgrass Institute
LESCO Incorporated
PO Box 10915
Rocky River, Ohio 44116-0915

Gardens Alive
5100 Schenley Place
Lawrenceburg, Indiana 47025

Lyman-Ritchie Sand & Gravel
4315 Cuming Street
Omaha, Nebraska 68131

97

Milorganite
735 North Water Street
Milwaukee, Wisconsin 53200

Tri State Turf & Irrigation Co.
6125 Valley Drive
Bettendorf, Iowa 52722

Monsanto Company
Agricultural Products Division
800 North Lindbergh Boulevard
St. Louis, Missouri 63167

United Horticultural Supply
4564 Ridge Dr. NE
Salem, Oregon 97303
Weathermatic Corporation
Telsco Industries
P.O. Box 180205
Dallas, Texas 75218-2005

NOR-AM Chemical Company
PO Box 7495
3509 Silverside Road
Wilmington, Delaware 19803

Wilbur-Ellis Company
215 North Summer Street
West Burlington, Iowa 52655

PBI/Gordon Corporation
PO Box 4090
1217 West 12th Street
Kansas City, Missouri 64101-9984

Williams Lawn Seed Company
PO Box 112
224 South Hills Drive
Maryville, Missouri 64468

Pickseed West Incorporated
PO Box 888
Tangent, Oregon 97389
Pursell
P.O. Box 450
201 W. Fourth St.
Sylacauga, Alabama 35150
O. M. Scott and Sons
14111 Scottslawn Road
Marysville, Ohio 43041
R.G.B. Laboratories Incorporated
1531 Charlotte Street
Kansas City, Missouri 64108
Rhone-Poulenc Chemical Company
PO Box 125
Blade Horse Lane
Monmouth Junction, New Jersey 08852
Spraying Systems Company
N Avenue at Schmale Road
Wheaton, Illinois 60187
Sustane Corporation
P. O. Box 19
Cannon Falls, Minnesota 55009
Terra Chemical Corporation
Box 218
Quimby, Iowa 51049
The Toro Company
Irrigation Division
Riverside, California 92500

28 06/03 4 2
29407 -

98

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. . . and justice for all
The Iowa Cooperative Extension Service’s programs and policies are consistent with pertinent
federal and state law s and regulations on nondiscrimination regarding race, color, national origin,
religion, sex, age, and disability.
Cooperative Extension Service, Iowa State University o f Science and T echnology and the United
States Department o f Agriculture cooperating. Robert M. Anderson, Jr., director, A m es, Iowa.
Distributed in furtherance o f the A cts o f G ttigtassjyf May 8 and June 30, 1914.

BEARD
COLLECTION