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THESis

 

 

This is to certify that the

thesis entitled

Effects of Weed Control Measures in
Established Alfalfa on Yield and
and Forage Quality

presented by

Dennis Robert Cosgrove

has been accepted towards fulfillment
of the requirements for

degree in Crop Sc1ence

 

 

 

Date May 10, 1983

0-7639

MS U is an Affirmative Action/Equal Opportunity Institution

 

 

 

 

MSU

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RETURNING MATERIALS:
Place in book drbp to
remove this checkout from
your record. FINES will
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stamped below.

 

 

WW W” by;

 

MGM USE Gilli

 

 

/<//- J3 73

EFFECTS OF WEED CONTROL MEASURES IN ESTABLISHED

ALFALFA 0N YIELD AND FORAGE QUALITY

By

Dennis R. Cosgrove

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE ,
Department of Crop and Soil Sciences

1983

ACKNOWLEDGMENTS

I would like to thank Dr. Michael Barrett for his guidance
and patience during the course of this study. I am grateful to have
an opportunity to work with him and proud to have him as a friend.
Appreciation is also expressed to Dr. J. v. Thomas of the M. S. U.
Animal Science Department for his assitance and advice concerning
forage analysis. Finally, I would like to thank Drs. Meggitt and
Penner and all of the faculty, staff and graduate students concerned
with the Michigan State Need Control Program for their assistance and
fbr making Michigan State University an exciting and enjoyable

experience.

ii

TABLE OF CONTENTS

List of Tables ........................ iv
Introduction ......................... 1
Literature Review ...................... 3
Weed Control and Forage Quality .............. 7
Materials and Methods .................... 10
Results and Discussion .................... 15
Site I. . . . ....................... 15
Weed Control ....................... 15
Influence of Herbicides on Forage Composition and Yield . 27
Influence of Herbicide Treatments on Forage Quality . . . 39
Site II .......................... 59
Weed Control ....................... 59
Influence of Herbicides on Forage Composition and Yield . 72
Influence of Herbicide Treatments on Forage Quality . . . 81
Site III .......................... 101
Weed Control ....................... 101

Influence of Herbicides on Forage Composition and Yield . 111

Influence of Herbicide Treatments on Forage Quality . . . 129

General Discussion ...................... 143

Literature Cited ....................... 149

iii

Table

10

ll

12

LIST OF TABLES

Treatments evaluated ..................

Harvest dates for the 1981 and 1982 growing season. . .

Orchardgrass control ratings at site one for the 1981

growing season .....................

Perennial grass control ratings at site one for the

1982 growing season. Treatments applied in 1981/82 . .

Quackgrass control ratings at site one for the 1981

growing season .....................

Perennial grass control ratings at site one for the
1982 growing season. Treatments applied 1980/81 and

1981/82 ........................

Perennial grass control ratings at site one for the

1982 growing season. Treatments applied in 1980/81 . .

Dandelion control ratings at site one for the 1981

growing season .....................

Dandelion control ratings at site one for the 1982

growing season. Treatments applied in 1981/82 .....

Dandelion control ratings at site one for the 1982
growing season. Treatments applied in 1980/81 and

1981/82 ........................

Dandelion control ratings at site one for the 1982

growing season. Treatments applied in 1980/81 .....

First harvest dry matter yields of total forage.
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one in the 1981 growing

Season .........................

iv

Page
12

13

16

17

19

22

23

25

26

28

29

31

13

14

15

16

17

18

19

20

21

22

23

Second harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one in the 1981 growing

season .........................

Third harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one in the 1981 growing

season .........................

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site one in

the 1981 growing season ................

First harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site one in the 1982 growing

season for treatments applied in 1981/82 ........

First harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one in the 1982 growing

season. Treatments applied in 1980/81 and 1981/82. . .

First harvest dry matter yields of total forage.
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1980/81 ........

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1981/82 ........

Third harvest dry matter yields of total forage.
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1981/82 ........

Second harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1980/81 ........

Third harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1980/81 ........

Second harvest dry matter yields of total forage.
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing

season for treatments applied in 1980/81 and 1981/82. .

V

32

33

34

36

38

40

41

42

43

 

24

25

26

27

28

29

30

31

32

33

34

535

Third harvest dry matter yields of total forage,
alfalfa, grass, and broadleaf weeds as influenced by
herbicide treatments at site one for the 1982 growing
season for treatments applied in 1980/81 and 1981/82. .

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site one in
the 1982 growing season for treatments applied in
1981/82 ........................

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site one for
the 1982 growing season for treatments applied in
1980/81 ........................

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site one for
the 1982 growing season for treatments applied in
1980/81 and 1981/82 ..................

First harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
one in the 1981 growing season .............

Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide
treatment at site one in the 1981 growing season. . . .

First harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
one in the 1982 growing season. ............

Percent alfalfa, grass and broadleaf weeds present
in first harvest forage as influenced by herbicide
treatment at site one in the 1982 growing season. . . .

Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site one
in the 1981 growing season ...............

Third harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site one
in the 1981 growing season ...............

Second harvest, in vitro digestible dry matter and acid
detergent fiber content of forage at site one in the
1982 growing season ..................

Third harvest protein, in vitro digestible dry matter

and acid detergent fiber content of forage at site
one in the 1982 growing season .............

.vi

45

46

47

48

50

51

52

53

55

56

57

58

 

36

37

38

39

40

41

42

43

44

45

46

47

‘48

49

50

Quackgrass control ratings at site two for the 1981

growing season .....................

Quackgrass control ratings at site two for the 1982

growing season. Treatments applied in 1981/82 .....

Quackgrass control ratings at site two for the 1982
growing season. Treatments applied in 1980/81 and

1981/82 ........................

Quackgrass control ratings at site two for the 1982

growing season. Treatments applied in 1980/81 .....

Dandelion control ratings at site two for the 1981

growing season .....................

Dandelion control ratings at site two for the 1982

growing season. Treatments applied in 1981/82 .....

Dandelion control ratings at site two for the 1982
growing season. Treatments applied in 1980/81 and

1981/28 ........................

Dandelion control ratings at site two for the 1982

growing season. Treatments applied in 1980/81 .....

White cockle control ratings at site two for the 1981

growing season .....................

First harvest white cockle control ratings at site
two for the 1982 growing season. Treatments applied

in 1981/82 .......................

First harvest white cockle control ratings at site
two for the 1982 growing season. Treatments applied

in 1980/81 .......................

First harvest white cockle control ratings at site two
for the 1982 growing season. Treatments applied in

1980/81 and 1981/82 ..................

First harvest shepherd's purse control ratings at site

two for the 1981 growing season ............

First harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site two in the 1981 growing

season .................. . ......

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site two in the 1981 growing

season .........................

vii

60

61

62

63

65

66

67

68

69

70

71

73

74

75

76

51

52

53

54

55

56

57

58

£59

(50

EN

Third harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site two in the 1981 growing

season .........................

First harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1981/82 .............

Second harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1981/82 .............

Third harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1981/82 .............

First harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 and 1981/82 .......

Second harvest yield of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 and 1981/82 .......

Third harvest yield of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 and 1981/82 .......

First harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 .............

Second harvest yields of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 .............

Third harvest yield of total forage, alfalfa, grass
and broadleaf weeds as influenced by herbicide treat-
ments at site two for the 1982 growing season for

treatments applied in 1980/81 .............

Season total dry matter yields of forage and alfalfa.
as influenced by herbicide treatments at site two

in the 1981 growing season ...............

viii

77

78

79

80

82

83

84

85

86

87

88

62

63

64

65

66

67

68

69

70

71

72

73

74

Season total dry matter yields of total forage and
alfalfa as influenced by herbicide treatments at site
two in the 1982 growing season. Treatments applied in
1981/82 ........................

Season total dry matter yields of total forage and
alfalfa as influenced by herbicide treatments at site
two in the 1982 growing season. Treatments applied in
1980/81 and 1981/82 ..................

Season total dry matter yields of total forage and
alfalfa as influenced by herbicide treatments at site
two in the 1982 growing season. Treatments applied in
1980/81 ........................

First harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site two
in the 1981 growing season ...............

Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treat-
ment at site two in the 1981 growing season ......

Second harvest protein, in vitro digestible dry
matter and acid detergent fiber content of forage at
site two in the 1981 growing season . . . . . .....

Third harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site two
in the 1981 growing season ..... . .........

First harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
two in the 1982 growing season ....... . .....

Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
two in the 1982 growing season .............

Third harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
two in the 1982 growing season. ............

Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treat-
ment at site two in the 1982 growing season ......

Quackgrass control ratings at site three for the 1981
growing season. . . ..................

Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1981/82 .....

ix

89

90

91

92

93

95

96

97

98

99

100

103

75

76

77

78

79

80

81

82

83

84

85

'86

87

88

Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1980/81 and
1981/82 ........................

Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1980/81 .....

Dandelion control ratings at site three for the 1981
growing season .....................

Dandelion control ratings at site three for the 1982
growing season. Treatments applied in 1981/82 .....

Dandelion control ratings at site three for the 1982
growing season. Treatments applied in 1980/81 and
1981/82 ........................

Dandelion control ratings at site three for the 1982
growing season. Treatments applied in 1980/81 .....

White cockle control ratings at site three for the
1981 growing season ..................

First harvest white cockle control ratings at site
three for the 1982 growing season. Treatments applied
in 1981/82 .......................

First harvest white cockle control ratings at site
three for the 1982 growing season. Treatments applied
in 1980/81 and 1981/82 ................

First harvest white cockle control ratings at site
three for the 1982 growing season. Treatments applied
in 1980/81 .......................

First harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1981 growing
season .........................

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1981 growing
season .........................

Third harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1981 growing
season .........................

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site three
in the 1981 growing season ...............

X

105

106

107

108

109

110

112

113

115

116

118

119

120

89

90

91

92

93

94

95

96

97

98

99

First harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1981/82. ........

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1981/82. . . . .....

Third harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1981/82 .........

Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site three in the

1982 growing season for treatments applied in 1981/82 . .

First harvest dry matter yields of total forage, alfalfa
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for

treatments applied in 1980/81 ..............

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1980/81 .........

Third harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1980/81 .........

Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site three in
the 1982 growing season for treatments applied in

1980/81 .. ........................

First harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1980/81 and 1981/82. . .

Second harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1980/81 and 1981/82. . .

Third harvest dry matter yields of total forage,
alfalfa, grass and broadleaf weeds as influenced by
herbicide treatments at site three in the 1982 growing

season for treatments applied in 1980/81 and 1981/82. . .

xi

121

123

124

125

127

128

130

131

132

100 Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site three in the
1982 growing season for treatments applied in 1980/81
and 1981/82 ........................ 133

101 First harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site three in
the 1981 growing season .................. 134

102 Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treat-
ment at site three in the 1981 growing season ....... 135

103 Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site three
in the 1981 growing season ................. 136

104 Third harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site three
in the 1981 growing season ................. 137

105 First harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site three
in the 1982 growing season ................. 138

106 Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treat-
ment at site three in the 1982 growing season ....... 139

107 Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site
three in the 1982 growing season .............. 141

108 Third harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site three
in the 1982 growing season ................. 142

'109 Savings vs. cost of some herbicide treatments causing

significant increases in first harvest forage protein
content .......................... 147

xii

INTRODUCTION

Hay was Michigans second leading field crop in value of production

for the 1981 growing season. Total hay production was 3,894,000 tons

of which 3,300,000 tons was alfalfa or alfalfa/grass mixtures. Hay pro-

duction involved 1,270,000 acres of Michigan farm land in 1981. This hay

was either utilized on the farm by livestock producers or sold as a cash

crop.

Heeds can reduce the value of alfalfa hay in several ways. Weeds

can compete with alfalfa plants for moisture and nutrients, they can slow

liay'drying'hithe field and they can reduce hay quality (11). Competition

from weeds in established stands of alfalfa can limit alfalfa growth but

Sfince the weeds are harvested along with the forage the total forage pro-

<1L1ction may not be effected by the presence of weeds. Weeds, however,

Eilre generally of lower quality as an animal feed than alfalfa and, there-
'FIJre, weeds in established alfalfa have the potential to lower the quality

(’1: the forage. In addition, competition from weeds reduces the density

and vigor of the alfalfa stand which in turn reduces the alfalfa stand life.
TFFIis results in the premature need to plow down the stand and rotate to

E“Mather crop or to re-establish the stand which is an expensive procedure.

(:CDInmolling weeds can extend the life of the alfalfa stand. This enables

1:}19 grower to spread the cost of establishing the alfalfa over a greater

number of years.

 

 

Most weed control measures 'hi alfalfa are concerned with stand
establishment and much research was done in this area (21, 23, 26, 30).
The benefits of weed control programs in established alfalfa are less
clear. Some investigators found weed control measures increased either
protein content or digestibility of forage (7, ll, 12). These increases,
in at least one case, resulted in a higher animal intake of forage and
higher milk production. In addition, feeding a forage with a high protein
content could reduce the need to purchase expensive protein supplements.
In other cases, however, weed control measures have failed to significantly
increase protein content or forage digestibility (31). Before weed
control programs in established alfalfa become widely accepted more
concrete benefits from their use must be demonstrated. The objectives
(of this study were: (1) to evaluate metribuzin [4-amino-6-tertfbutyl-3-
(methylthio)-as—triazine-5(4)+)one] , pronamide [3,5-dichloro-N-Cl ,1-

dimethyl-Z-propynyl )benzamide] , simazine [2-chloro-4,6-bis(ethy1amino)-
j§;—triazine, and terbacil [3-tertfbutyl-5-chloro-6-methluracil] for their
£21=ficacy as weed control agents in established alfalfa. (2) To determine
'tlie effect of stand density and weed pressure on the performance of these
'1eerbicides. (3) To determine the effects of these herbicde treatments on

fOrage yield, and (4) To determine the effects of these weed control

measures on forage qualitY-

LITERATURE REVIEW

The effectivenss of chemical weed control in established stands of

a1 falfa is influenced by several factors. Timing of application effects

the spectrum of weeds controlled and also the extent of control. Ilnicki

and Hist (18) found no response from curlydock [Rumex crispus (L.)], daisy

 

f"! eabane (Erigeron strigosus Muhl.) or white cockle (Lychnis alba Mill.)

 

to fall applications of terbacil, simazine or several other herbicides.

Ye‘l 1 ow rocket (Barbarea vulgaris R. Br.) and chickweed [Stellaria media

 

(L - ) ] were both controlled with fall or spring applications of the same
he r‘b icides. Sheaffer and Wyse (31) found no differences in dandelion
(La Y‘axacum officinale Weber.) control in the first cutting with spring

heI"I3icide treatments compared to fall treatments at two of three sites

tes ted. At the remaining site, spring applied metribuzin at 0.80 kg/ha

and 1.1 kg/ha significantly reduced common dandelion populations compared
to the same treatments fall applied. Arnold and Oneal (3) reported less
downy brome [Bromus tectorum (L.)] control from fall applications of
metY‘TDUZln and terbacil than spring applications of the same materials.
V'i Ste and Sanborn (45) found October applications of pronamide to be
ol3t1’mal for quackgrass [Agropyron repens (L.)] control.

Stand density and the size of the weed population are also important
faCtors which affect weed control in established alfalfa. Davis et a1. (6)

1:Ol—lhd quackgrass suppression with pronamide increased as alfalfa stand

de"Sity increased. Pagano et. a1. (24) found total forage yields decreased

following a metribuzin application in areas with severe weed infestations.
In areas with high alfalfa populations, total forage yields were increased
Fortino (14) observed similar results using metribuzin “and determined
that benefits were maximized by alfalfa stands containing 4 or more alfalfa
plants/ftz. Triplet et. a1. (35) found alfalfa populations as low as 10

to 20 plants/m2 were able to utilize resources made available as a result

of a pronamide treatments.

Longevity of weed control is another factor which must be taken into
con sideration when discussing weed control programs in established alfalfa.
Shea ffer and Wyse (31) observed that, of the treatments applied, only
but h ‘i dazole (3[5-C1 ,1-dimethy1 ethyl )-l ,3,4-thiadiazol-2-yl ]-4-hydroxy-l-

methyl-Z-imidazoli-dinone) reduced common dandelion populations the year

f01 'I owing treatment. Robison et. a1. (29) compared several herbicides

and observed little residual weed control the year following treatment,

a1 1: hough, in some cases there appeared to be enough herbicide residue to
cau se alfalfa injury if the treatment was reapplied at the original rate.
ROb ‘T son does not specify which treatments caused alfalfa injury. Fawcett
et - al. (12) found annual applications of pronamide were necessary for

C“Jackgrass control in stands of alfalfa with 10 to 20 crowns/m2 but that
Control persisted into the second year in stands with 40 to 50 crowns/m2.

SWah (33) observed that downy brome control from atrazine, (2-chloro-4-

etharlamine-6-isopropylamina-S-triazine) simazine, and terbacil decreased

to 1 ess than half and broadleaf weed control ceased 18 months after applica-

t'i Ons. Duke (7) reported quackgrass reinfestation of pronamide treated

p‘l Ots occurred in July of the first cropping year following treatment and

“0 difference in quackgrass populations among treatments the second cropping
year following treatment.

A fourth factor influencing weed control in established alfalfa is
the weed species present. Annual broadleaf weeds such as shepherd's purse
[Capsella bursaLpastoris (L.) medic.] and chickweed are generally easily
controlled. Kapusta (19) reported excellent common chickweed control with
cyanazine (4.5 kg/ha), simazine (1.7 kg/ha) and terbacil (1.1 kg/ha).
Pruss (28) found December applications of‘simazine at 1.12 kg/ha controlled
shepherd's purse. Pagano et. a1. (24) found shepherd's purse to be controlled
by a pplication of metribuzin at 0.56 kg/ha to dormant alfalfa. Peters and
0' Leary (27) obtained shepherd's purse control with spring applications of
terbacil at 0.56 and 1.12 kg/ha, as well as spring applied simazine at 1.12
and 2 .24 kg/ha.
Control of perennial broadleaf weeds such as white cockle and dandelions
1" established stands of alfalfa has proven somewhat difficult. Pearson
and Meggitt (25) observed that simazine at 1.12 and 2.24 kg/ha and terbacil
at 1 - 12 kg/ha applied in early spring gave excellent control of white
CDC k1 e. Pagano et. a1. (24) found 0.84 kg/ha of metribuzin to be necessary
for control of white cockle whereas Fortino (14) reported difficulty in
"hi te cockle control with metribuzin rates of 1.12 kg/ha. Peters and
0' Leary (27) reported severe chlorosis, but not death, with spring treat-
ments of simazine (2.24 kg/ha), terbacil (0.56 kg/ha) and bromacil
(5‘bromo-Bsec-butyl-6-methyluracil) (0.56 and 1.12 kg/ha). Applications
°T 2 ,4-03 [4-(2,4-dichlorophenoxy)butanoic acid] had little effect. Currey
and Peters (5) reported partial control of white cockle with late summer
3991 ications of either terbacil or simazine at 1.12 kg/ha. Duke and Spear
(3) observed satisfactory control of white cockle with 2.24 kg/ha of

simazine spring applied but poor control with 2.24 or 3.36 kg/ha of

Simazine applied in the fall. Good control was also observed with terbacil
or bromacil at 2.24 kg/ha, but these rates were injurious to the alfalfa.
Several herbicide treatments have been evaluated for control of
dandelion in established alfalfa. Duke and Spear (8) observed dandelion
control with spring applications of terbacil at 2.24 kg/ha and bromacil
at 1 -12 and 2.24 kg/ha. However, these rates were injurious to the al-
faT ‘Fa. No treatment gave good control when applied in the fall. Triplett
et- a1. (35) found December applications of 2,4-D [(2,4-dichlorophenoxy)
acetic acid] reduced the number of seedling dandelions, but did not affect
the number of mature dandelions. Pagano et. al. (24) observed only
Par‘t'i a1 control of dandelions with metribuzin at 0.84 kg/ha. Sheaffer
and Wyse (31) treated established stands of alfalfa at four separate
10Cations with fall and spring applied buthidazole, metribuzin, simazine
and 2 ,4-08. They observed that on courser textured soils all treatments,
except spring applied simazine at one site and spring applied simazine
as Well as fall applied metribuzin and 2,4-DB at a second site, reduced
dar‘Iclelion populations at the third cutting. Pearson and Meggitt (25)
1EOUYWd spring applications of terbacil at 1.12 kg/ha provided good dandelion
control. Duke and Hunt (9) observed that spring applications of metribuzin
"Ere more effective for dandelion control than fall applications. Dutt
(1 0 ) reported excellent and fair control of dandelion with metribuzin and
te"‘bacil, respectively, but does not specify the time of application.
wadd‘ington (46) obtained control of dandelion in established alfalfa with
dich‘lobenil (2.2 kg/ha), asulam (methylsulfanilycarbamate) (4.45 kg/ha)
0" terbacil (1.1 kg/ha).
0f the grass species, quackgrass is the most serious problem in

a] 'Fana stands in Michigan. It is a perennial which reproduces both by

Seed and by underground rhizomes (32). In addition to its highly competitive
IIature, there is also evidence which suggests quackgrass has an all allelo-
pathi’c effect on some crops (20). The best quackgrass control from a
herbicide program in established stands of alfalfa was obtained through
fa] 1 applications of pronamide. Vista and Sanborn (45) observed good
quackgrass control with pronamide at both 0.84 and 1.68 kg/ha. Duke (7)
obta 1' ned excellent quackgrass control with pronamide at 1.68 kg/ha whether
app‘l 'i ed in the spring or fall. Dutt (11) observed nearly complete suppres-
sion of quackgrass with fall applications of pronamide at 1.71 kg/ha.
Harvey and Conners (16) found excellent quackgrass control with pronamide
at O - 84 and 1.68 kg/ha, although the 0.84 kg/ha rate did not provide season
10719 control. Fortino (14) also observed suppression of quackgrass, but

"013 Control, using 1.12 kg/ha metribuzin.

Mntrol and Forage Quality

Need control measures generally lead to higher crop yield. However,

this 1‘ s not always the case with weed control programs in established

“1:31 ‘Fa. Effective weed control measures in existing stands of alfalfa

Often result in lower or unchanged total forage yields. Fawcett and
Harvey (12) observed that fall applications of pronamide decreased total
f0"age yields in fields with low alfalfa densities. However, total
a1 1:61 ‘Fa yields were increased with some pronamide treatments. Total forage
“91 ds either remained constant or increased slightly in fields with higher
“1:31 ‘Fa stand densities. Dutt (10) observed that herbicides either de-
c"Eased or had no effect on total forage dry matter 719195- However,
pronamide applications significantly increased total alfalfa yields. Duke

““9 Spear (8) found total forage yields either remained the same or

deer“5-‘ased as a result of herbicide treatments to established alfalfa

infested with several species of broadleaf weeds. Total alfalfa yields
Were not changed. Sheaffer and Wyse (31) found no increase in either total
forage yield or total alfalfa yields as a result of controlling common dan-
delion in established stands of alfalfa. Although the benefits of weed
control in established alfalfa are not apparent in increased forage yields,
a potential benefit exists in increased forage quality.

Protein content and forage digestibility are both accepted criterion
for Forage quality. Cord (4) showed crude protein in alfalfa hay to be
negat “ively correlated with weed content. The digestibility of protein in a
forage increases with increasing protein content (13, 15, 17). As alfalfa
is h 'i gher in crude protein than many weed species (22, 34), increasing the
alfa1 'Fa component of a forage could increase the protein percentage of that
forage .

Forage digestibility is related to the fiber content of the forage.
The 12$ ber fraction of a forage is difficult to define (43). Van Soest
cons ‘3 ders the plant cell walls to represent the total fibre fraction (39),
the cell contents being completely digestible by ruminants (40). The plant
C91 1 wall constituents include hemicellulose and cellulose fractions which
are partly digestible, and a lignin fraction which is completely indigestible.
CE] 1 wall constituents may be determined using the neutral detergent method
of Van Soest and Wine (44). However, this neutral detergent fiber (NDF)
ShOWS little correlation to digestibility (42). The acid detergent method
of Van Soest (41) only recovers the cellulose and lignin fractions of the
CE] 1 wall constituents and shows a better correlation with digestibility

(37 s 38). The invitro rumen fermentation technique of Tilley and Terry (36).

0f 31 T methods so far investigated for estimating the dry matter digesti-

bi] ‘ity of a forage, has proven to be the most accurate (1, 42). Several

 

7'Ilvestigators have used these tests to determine the effects of weed
Control measures on forage quality. lemme et. al. (34) showed a significant
increase in both crude protein and in-vitro digestible dry matter (IVDDM) for
treated alfalfa compared to untreated alfalfa infested with several annual
broad] eaf weeds. Fawcett et. a1. (12) found significant protein increases
in 'F'i rst cutting hay as a result of pronamide applications to alfalfa
infested with quackgrass. IVDDM was also increased in all three cuttings.
There was no effect on acid detergent fiber content. Dutt (10) found little
difference in crude protein (CP) in treated alfalfa infested with perennial
broad 1 eaf weeds. However, significant first cutting protein increases
were observed with applications of pronamide to an alfalfa stand heavily
infested with quackgrass. In a second study, Dutt (10) found significant
increases in both CP and IVDDM as a result of pronamide application to
quac: Kgrass infested alfalfa. Duke (7) also reported significant protein
incr~eases in the first cutting of pronamide treated alfalfa. Sheaffer and
"5'59 ( 31) observed no consistent increases in either CP or IVDDM as a result

0f Controlling common dandelion in established alfalfa.

MATERIALS AND METHODS

Weed control experiments were conducted in established alfalfa
at three locations in East Lansing, Michigan.

The soil type at location one was a Riddles-Hillsdale sandy loam
(161’ ne-coarse)1oamy, mixed typic hapludalfs). A soil test indicated pH
0f 7 - 2, 2.41 percent organic matter, 134 kg/ha available P and 102 kg/ha
ava ‘i 1 able K. Three hundred pounds K20 was applied after first cutting
in 1 981 as recomended by the soil test. Site two was a Capac loam
(f1. rte-loamy, mixed mesic Aeric Ochraqualfs). A soil test indicated a
pH Of 7.2, 3.69 percent organic matter, 92 kg/ha available P and 170 kg/ha
ava ‘3 1able K. One hundred fifty pounds K20 was applied after first cutting

in 1 981 as recommended by the soil test. The soil type at site three

Was also a Capac loam. A soil test indicated a pH of 7.1, 3.88 percent
Pbganic matter, 29 kg/ha available P and 349 kg/ha available K. No
add ‘i tional fertilizer was applied. The alfalfa variety was Vernal at all
t"“"ee sites. Site one was a seven year old stand with a stand density of

30 plants/m2 and severe weed pressure. Site 2 was a 2 year old stand with

56 Dlants/m2 and light weed pressure. Site 3 was a 2 year old stand with
58 plants/m2 and severe weed pressure.

Visual weed control ratings were made using a 0-100 scale, 0 being
no

control; 100 being complete control. Ratings were done just prior to
each cutting date. Botanical composition of the forage at harvest was

determined by cutting a square meter sample from each plot and separating

1O

 

 

11

the forage into alfalfa, broadleaf weed and grass weed components.

Total forage yields were determined three times a year when 10% of the

alfalfa plants had blooms present (1/10 bloom stage). Harvest dates

for the three sites are shown in Table 2. Herbicides were applied

November 24, 1980 and March 23, 1981, and November 24, 1981 and March

29, 1982. Alfalfa was dormant at all applications. Herbicide com-

binations are shown in Table 1. All treatments were applied with a

tractor mounted sprayer deliverying 261 L/ha at 30 psi.

The experimental design was a randomized complete block with

fou r‘ replications. All data was analyzed using analysis of variance

tec hniques.

Yields were determined by cutting a 4.31 m2 strip down the middle

01: each plot with a flail type forage harvester. One thousand gram

SamTZI'Ies were collected at the time of harvest for dry matter determination
The Se samples were dried at 65°C, ground to pass through a 40 mesh screen

and stored for later analysis.

Yields were determined and hand separations were performed in
198 1 on all plots which received herbicide treatments. In 1982, yields
and separations were performed only on forage from plots which received
the following treatments: metribuzin (0.56 kg/ha) fall applied, metribuzin
(1 - 1 2 kg/ha) spring applied, pronamide (1.68 kg/ha) fall applied, and
pronamide (1.68 kg/ha) fall applied followed by metribuzin (1.12 kg/ha

SPY‘i ng applied as well as the untreated control. These four herbicide

t"‘eatments were chosen due to the fact that they were representative of
the spectrum of weed control observed during the course of the study.
MetIr‘ibuzin (0.56) kg/ha represented treatments providing only annual
broadleaf weed control, metribuzin (1.12 kg/ha) spring applied was

Y‘eDY‘esentative of treatments providing both annual and perennial weed

 

 

12

Table l. Treatments evaluated.

 

 

Rate Appl Rate Appl
Treatment (kg/ha) Time Treatment (kg/ha) Time
1. Pronamide 1.12 Fall 7. Pronamide 1.68 Fall

Metribuzin 1.12 Spring
2. Pronamide 1.68 Fall
8. Simazine 1.40 Fall
3. Pronamide 1.68 Fall
Simazine 1.40 Fall 9. Metribuzin 0.56 Fall

4. Pronamide 1.68 Fall 10. Terbacil 1.12 Fall
Metribuzin 0.56 Fall
11. Metribuzin 1.12 Spring
5. Pronamide 1.68 Fall
Terbacil 1.12 Fall 12. Terbacil 1.12 Spring

6. Pronamide 1.68 Fall 13. Untreated
Terbacil 1.12 Spring

 

 

13

Table 2. Harvest dates for the 1981 and 1982 growing season.a

 

 

 

 

 

 

 

dates.

Site I II III
1981 1982 1981 1982 1981 1982
I 6/9 6/7 7/17 7/15 9/15 8/20
II 6/9 6/7 7/14 7/12 8/12 8/17
III 6/9 6/7 7/14 7/14 9/1 8/17

 

aAll harvests were made when alfalfa was at the 1/10 bloom stage.

 

14

control. Pronamide (1.68 kg/ha) fall applied was representative of
treatments which provided control of perennial grasses only and pronamide
(1.68 kg/ha) fall applied followed by metribuzin (1.12 kg/ha) spring
applied was representative of treatments which provided control of both
annual and perennial broadleaves and grasses. Determinations were made
on plots which received these treatments in 1980/81, 1981/82 or in both
1980/81 and 1981/82. Forage quality analysis was performed in 1981 on
plots which received these treatments in 1980/81 and in 1982 on plots
which received these treatments only in 1981/82. No analysis was per-
formed in 1982 on forage from plots receiving treatment only in 1980/81
or in both 1980/81 and 1981/82.

Samples were analyzed for crude protein using the Kjeldahl procedure
(2). In vitro digestible dry matter (IVDDM) was determined using the
Tilley and Terry technique (36) which involves digestion of 0.5 gram
forages samples for 48 hours in rumen fluid obtained from fistulated
cows followed by the addition of pepsin, acidification and an additional
48 hour digestion. Samples are then filtered, dried and weighed to
determine percent dry matter lost. Acid detergent fiber content was
determined using the procedure by Van Soest (41) in which 1.0 gram samples
are refluxed in 1.0M sulphuric acid solution containing hexaderyl-
trimethyl ammonium bromide for 1 hour. These samples are then filtered,

dried and weighed to determine percent dry matter lost.

 

 

RESULTS AND DISCUSSION

For ease of discussion, the results of this study are arranged
by site. Within each site there are three sections: Weed Control,
Influence of Herbicides on Forage Composition and Yield, and Influence

of Herbicide Treatments on Forage Quality.
SITE I

Weed Control
Orchardgrass (Dactylis glomerata L.) was the most prevalent perennial
grass species at the first cutting. Several herbicide treatments provided
orchardgrass control in both 1981 and 1982. Pronamide at either 1.12
kg/ha or 1.68 kg/ha (Tables 3 and 4) fall applied gave good orchardgrass
control with no significant difference between the two rates. Pronamide
(1.68 kg/ha) fall applied in combination with simazine (1.46 kg/ha),
metribuzin (0.56 kg/ha), or terbacil (1.12 kg/ha) all provided good
orchardgrass control. Metribuzin (0.56 kg/ha) fall applied provided
poor control of orchardgrass in both 1981 and 1982. Terbacil (1.12 kg/ha)
fall applied provided poor control in 1981 but good control in 1982.
Simazine (1.46 kg/ha) fall applied provided fair to good control both
.Years. Ratings for this treatment were 92% in 1981 and 62% in 1982.
Spring applied metribuzin (1.12 kg/ha) provided significantly better
(Birchardgrass control than fall applied metribuzin (0.56 kg/ha) in 1981,

15

16

Table 3. Orchard grass control ratings at site one for the 1981
growing season.a

 

% Control

 

 

 

 

 

 

Rate Harvest

Herbicide ,(kg/ha), I II
Fall Treatments
Pronamide 1.12 97a 96abc
Pronamide 1.68 99a 80bcd
Simazine 1.46 92a 98ab
Metribuzin 0.56 29b 69d
Terbacil 1.12 28b 77cd
Pronamide + Simazine 1.68 + 1.46 100a 94abc
Pronamide + Metribuzin 1.68 + 0.56 99a 94abc
Pronamide + Terbacil 1.68 + 1.12 993 95abc
Spring Treatments
Metribuzin 1.12 95a 76cd
Terbacil 1.12 100a 97abc
Fall/Springglreatments
Pronamide/Metribuzin 1.68 + 1.12 993 96abc
Pronamide/Terbacil 1.68 + 1.12 1003 100a
Control 0b 0b

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

 

17

 

 

 

 

 

 

 

Table 4. Perennial grassa control ratings at site one fgr the 1982
growing season. Treatments applied in 1981/82 .
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 82cdef 72cde 82bcde
Pronamide 1.68 94ef 72cde 67bcd
Simazine 1.46 62bc 20ab 62bc
Metribuzin 0.56 40ab 20ab 52b
Terbacil 1.12 B5cdef 55bc 57bc
Pronamide + Simazine 1.68 + 1.46 94ef 82cde 62bc
Pronamide + Metribuzin 1.68 + 0.56 97ef 87de 82bcde
Pronamide + Terbacil 1.68 + 1.12 92cdef 92e 57bc
Spring Treatments
Metribbzin 1.12 72bcd 62cd 65bcd
Terbacil 1.12 82cdef 75cde 67bcd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 77bcde 82cde 94de
Pronamide/Terbacil 1.68 + 1.12 100f 92e 82bcde
Control 03 0a 0a

 

aThe perennial grass at the first harvest is orchardgrass. At

harvest two and three is quackgrass.

bValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

18

although there was no significant difference between the two treatments
in 1982. Both metribuzin rates only provided fair control (40% and 72%
respectively) in 1982. Similar results were obtained with terbacil
(1.12 kg/ha) spring applied. Spring treatment in 1981 provided signifi-
cantly better control than fall application. However, there was no
significant difference between the two application times in 1982. These
results may be partly attributed to a dry spring in 1982. The herbicide
did not move into the active root zone of the orchardgrass until a
significant amountirfgrowth had taken place. Ratings for metribuzin and
terbacil spring applied at 1.12 kg/ha in 1981 were 95% and 100% respectively
compared to 72% and 82% in 1982. Fall applied pronamide (1.68 kg/ha),
followed by metribuzin (1.12 kg/ha) spring applied, provided excellent
orchardgrass control in 1981 although the combination did not improve
control over either herbicide alone. The same was true with pronamide
(1.68 kg/ha) fall applied followed by terbacil (1.12 kg/ha) spring
applied. Similar results were obtained in 1982, although pronamide
(1.68 kg/ha) fall applied followed by terbacil (1.12 kg/ha) spring
applied provided significantly better control than when followed by
metribuzin (1.12 kg/ha).

Quackgrass was the most prevalent perennial grass species at the
second and third cuttings. Several investigators found pronamide pro-
vided very good quackgrass control (7, ll, 45). Similar results were
observed in this study. Pronamide at 1.12 and 1.68 kg/ha fall applied
provided good quackgrass control in 1981 with no significant difference
[between the two treatments (Table 5). Pronamide (1.68 kg/ha) fall
Eipp11ed in combination with simazine (1.46 kg/ha), metribuzin (0.56

‘(g/ha) or terbacil (1.12 kg/ha) provided excellent quackgrass control.

19

 

 

 

 

 

 

 

Table 5. Quackgrass control ratings at site one for the 1981 growing
season.a
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 100a 96ab 77ab
Pronamide 1.68 100a 99a 76ab
Simazine 1.46 70c 87bc 52bcd
Metribuzin 0.56 0d 30ef 40bcde
Terbacil 1.12 15d 44de 20de
Pronamide + Simazine 1.68 + 1.46 100a 99a 64abc
Pronamide + Metribuzin 1.68 + 0.56 100d 94ab 77ab
Pronamide + Terbacil 1.68 + 1.12 87bc 88abc 4lbcde
Springglreatments
Metribuzin 1.12 87bc 68cd 32cde
Terbacil 1.12 94ab 97ab 73ab
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 100a 99a 74ab
Pronamide/Terbacil 1.68 + 1.12 100a 96ab 89a
Control Od 0f 0e

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

 

20

however, metribuzin or terbacil alone at these rates provided poor
control. Similar results were obtained with these treatments in 1982
although the degree of control was generally less (Table 4). Pronamide
at 1.12 and 1.68 kg/ha gave greater than 90% quackgrass control in 1981
but only 72% control in 1982. Pronamide (1.68 kg/ha) in combination with
simazine or metribuzin at the rates mentioned above gave 99% and 44%
control respectively in 1981 and 82 and 87% control in 1982. Metribuzin
(1.12 kg/ha) spring applied provided significantly better quackgrass
control than fall applied metribuzin at 0.56 kg/ha in both 1981 and 1982.
Metribuzin (1.12 kg/ha) spring applied in combination with a fall appli-
cation of pronamide (1.68 kg/ha) provided significantly better quackgrass
control than metribuzin alone in 1981. In 1982 there was no difference
in the two treatments. Control with this treatment was no better than
pronamide (1.68 kg/ha) applied alone in the fall in either year.
Pronamide (1.68 kg/ha) fall applied followed by terbacil (1.12 kg/ha)
spring applied provided excellent quackgrass control, although control
with this combination was no better than either treatment alone in 1981 and
1982. Terbacil (1.12 kg/ha) spring applied provided significantly
better quackgrass control than did the same treatment fall applied in
1981 but not 1982. There were few differences in quackgrass control
between treatments at the third cutting in either year. Pronamide (1.68
kg/ha) fall applied followed by terbacil (1.12 kg/ha) spring applied
provided greater than 80% quackgrass control at the third cutting in both
years. The same rate of pronamide followed by a spring treatment of
metribuzin at 1.12 kg/ha provided 92% quackgrass control in 1982.

All treatments which were applied in both 1980/81 and 1981/82

gave excellent quackgrass control thoughout the season in 1982 with the

21

exception of simazine (1.46 kg/ha) fall applied (Table 6). Orchardgrass
control with this treatment at the first cutting was not significantly
different from the untreated check. Quackgrass control at the second
and third cuttings was also poor with this treatment.

Herbicides applied to established stands of alfalfa have been
found, in some cases, to provide poor weed control the year following
treatment (7, 12, 31). In this study treatments applied in 1980/81 showed
reduced perennial grass control in 1982 when compared to treatments
applied in 1981/82 or 1980/81 and 1981/82 (Table 7). There were very
few significant differences between treatments, although a number of
treatments reduced quackgrass populations compared to the untreated
control. There was no difference between pronamide 1.12 kg/ha and 1.68
kg/ha fall applied. There were also no significant differences in pro-
namide applied in the fall with simazine (1.46 kg/ha), metribuzin (0.56
kg/ha), or terbacil (1.12 kg/ha) or with simazine (1.46 kg/ha), metribuzin
(0.56 kg/ha) or terbacil (1.12 kg/ha) applied alone. Pronamide (1.68 kg/
ha) + metribuzin (0.56 kg/ha) fall applied did give control than metribu-
zin (0.56 kg/ha) fall applied alone. None of these treatments gave
better than 62% control. Metribuzin (1.12 kg/ha) spring applied gave
no better control than metribuzin (0.56 kg/ha) fall applied. Neither
treatment was significantly better than the untreated check. Terbacil
(1.12 kg/ha) spring applied gave better control than the same treat-
ment applied in the fall. Pronamide (1.68 kg/ha) fall applied + metribu—
zin (1.12 kg/ha) spring applied was no better than either treatment
alone or than metribuzin (0.56 kg/ha) fall applied.

Similar results were observed with quackgrass control at the second

and third cuttings, although slightly better quackgrass control was

Table 6. Perennial grassa

growing season.

22

control ratings at site one for the 198%
Treatments applied 1980/81 and 1981/82.

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 84c 85c 85bc
Pronamide 1.68 lOOc 94c 87bc
Simazine 1.46 45ab 42b 77b
Pronamide + Simazine 1.68 + 1.46 100c 100c 90bc
Pronamide + Metribuzin 1.68 + 0.56 97c 92c 89bc
Spring Treatments
Metribuzin 1.12 85cdef 85c 80bc
Terbacil 1.12 97c 89c 77b
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 lOOc 90c 90bc
Pronamide/Terbacil 1.68 + 1.12 lOOc 94c lOOc
Control 0a 0a 0a

 

aThe perennial grass at the first harvest is orchardgrass. At

harvest two and three is quackgrass.

b

Values in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

 

23

 

 

 

 

 

 

 

 

Table 7. Perennial grassa control ratings at site one for the 1982
growing season. Treatments applied in 1980/81.b
% Control
Rate Harvest

Herbicide (kg/ha) I II 111
Fall Treatments
Pronamide 1.12 50bcd 67cd 85cd
Pronamide 1.68 55bcde 42bcd 82bcd
Simazine 1.46 52bcde 40abcd 72bcd
Metribuzin 0.56 15ab 35abc 62bc
Terbacil 1.12 l7abc 12ab 57bc
Pronamide + Simazine 1.68 + 1.46 47abcd 47bcd 90cd
Pronamide + Metribuzin 1.68 + 0.56 62cde 45bcd 55bc
Pronamide + Terbacil 1.68 + 1.12 70dc 57cd 70bcd
Spring Treatments
Metribuzin 1.12 l7abc 35abc 42ab
Terbacil 1.12 75de 72d 67bcd
Fall/Springglreatments
Pronamide/Metribuzin 1.68 + 1.12 52bcde 70cd 80bcd
Pronamide/Terbacil 1.68 + 1.12 87e 72d 60bc
Control 0a 0a 0a

aThe perennial grass at the first harvest is orchardgrass. At

harvest two and three is quackgrass.

bValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

24

observed at the third cutting than the second. The better control was
probably a result of less quackgrass regrowth in the third cutting.
Spring applications of metribuzin and terbacil were previously
found to provide good control of dandelion (8, 10, 35). In this study
metribuzin or terbacil spring applied at 1.12 kg/ha alone or in combination
with fall applied pronamide (1.68 kg/ha) gave better than 90% dandelion
control at the first cutting in 1981 (Table 8). These same treatments
provided only fair dandelion control at the first cutting in 1982 with
control ranging from 77 to 82% (Table 9). There was no difference in
control between treatments with or without pronamide either year. Dande-
lion control with pronamide alone was not significantly different than
the untreated check. Metribuzin (1.12 kg/ha) spring applied provided
significantly better dandelion control at the first cutting in both
years than did metribuzin (0.56 kg/ha) fall applied. Control at the
second cutting was significantly better at the 1.12 kg/ha rate spring
applied than the 0.56 kg/ha rate fall applied in 1981. There was no
difference between the two treatments at the second cutting in 1982 or
at the third cutting in either year. There were no significant
differences between fall applications of simazine (1.46 kg/ha), metribuzin
(0.68 kg/ha) or terbacil (1.12 kg/ha) at any cutting in 1981 with all
treatments providing poor dandelion control. Control ratings with these
treatments ranged from 45% to 75% at the first cutting with control de-
creasing at the subsequent cuttings. Terbacil (1.12 kg/ha) fall applied
provided significantly better dandelion control than either fall applied
metribuzin (0.56 kg/ha) or simazine (1.46 kg/ha) at the first cutting in
1982. Control with this treatment was poor. There were no significant

differences between these treatments at the subsequent cuttings. Duke

25

 

 

 

 

 

 

 

Table 8. Dandelion control ratings at site one for the 1981 growing
season.6
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 0e 0f 23cd
Pronamide 1.68 38de 15ef 13cd
Simazine 1.46 67cd 68bcd 47bc
Metribuzin 0.56 42de 60cd 40bcd
Terbacil 1.12 42de 54cd 43bc
Pronamide + Simazine 1.68 + 1.46 75de 50cd 35bcd
Pronamide + Metribuzin 1.68 + 0.56 66cd 45de 32cd
Pronamide + Terbacil 1.68 + 1.12 72bcd 69bcd 28cd
Springglreatments
Metribuzin 1.12 93abc 88ab 69ab
Terbacil 1.12 9labc 79bc 42bc
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 94ab 68bcd 26cd
Pronamice/Terbacil 1.68 + 1.12 99a 98a 91a
Control 0e 0f 0d

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

26

 

 

 

 

 

 

 

Table 9. Dandelion control ratings at site one for the 1982 growing
season. Treatments applied in 1981/82.a
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 0a 0a lOab
Pronamide 1.68 0a 0a 0a
Simazine 1.46 30abc 52bcdef 27abcd
Metribuzin 0.56 35bc 50bcde 32bcde
Terbacil 1.12 65def 40bcd 35bcdef
Pronamide + Simazine 1.68 + 1.46 45bcd 55cdefg 50defg
Pronamide + Metribuzin 1.68 + 0.56 l7ab 20ab l7abc
Pronamide + Terbacil 1.68 + 1.12 57cde 37bc 50defg
Spring Treatments
Metribuzin 1.12 77efg 65cdefgh 62fgh
Terbacil 1.12 77efg 77fgh 7Zgh
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 82fgh 67defgh 7Zgh
Pronamide/Terbacil 1.68 + 1.12 77efg 65cdefgh 60efgh
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

an

2“.
i l-

a";
wile

5‘-

"fl

--U

r!

27

and Spear (8) also observed poor dandelion control from fall applications
of terbacil. None of the fall applied treatments provided better
dandelion control hicombination with pronamide than alone.

Dandelion control generally decreased as the season progressed.
Control was very poor at the third cutting in both years with_few treat-
ments providing great than 60% control.

Treatments applied in both 1980/81 and 1981/82 provided slightly
better dandelion control than one year applications in some cases in
1982 (Table 10). Metribuzin (1.12 kg/ha) and terbacil at the same
rate spring applied provided very good dandelion control in the first
cutting although control decreased as the season progressed. The addi-
tion of pronamide (1.68 kg/ha) fall applied did not improve dandelion
control. Pronamide (1.68 kg/ha) + metribuzin (1.12 kg/ha) spring applied
provided significantly better dandelion control than pronamide (1.68 kg/
ha) + metribuzin (0.56 kg/ha) fall applied in all three
cuttings.

Dandelion control was reduced in 1982 in plots treated in 1980/81
(Table 11) compared to those treated in 1981/82 (Table 9) or in both
1980/81 and 1981/82 (Table 10). There were no significant differences
in dandelion control between any of the broadleaf materials tested at
any cuttings with the exception of terbacil (1.12 kg/ha) spring applied
in combination with pronamide (1.68 kg/ha) fall applied. This treatment
showed significantly better control than any other treatment at the first

cutting and several other treatments at the second and third cuttings.

Influence of Herbicides on Forage Composition and Yield
Site one was located in a poor stand of alfalfa (30 plants/m2)

with severe weed pressure. Fawcett and Harvey (12) found applications

v-v

".J tjl

In

28

Table 10. Dandelion control ratings at site one for the 1982

season. Treatments applied in 1980/81 and 1981/82.

growing

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) I1 II III
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 Ga 22ab 0a
Simazine 1.46 70cd 55bcd 45bc
Pronamide + Simazine 1.68 + 1.46 50bc 42bc 60cd
Pronamide + Metribuzin 1.68 + 0.56 40b 27ab 27ab
Spring Treatments
Metribuzin 1.12 89de 72de 57cd
Terabcil 1.12 87de 77de 70cd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 92e 80de 75d
Pronamide/Terbacil 1.68 + 1.12 94e 85e 90e
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

29

Table 11. Dandelion control ratings at site one for the 1982 growing
season. Treatments applied in 1980/81.a

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) II II III
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 Sab 0a 0a
Simazine 1.46 lSabc 47bcde 27ab
Metribuzin 0.56 37bcdef 45bcde 35bcd
Terbacil 1.12 25abcd 30abc 32bc
Pronamide + Simazine 1.68 + 1.46 15abc 27ab 20ab
Pronamide + Metribuzin 1.68 + 0.56 25abcd 25ab 22ab
Pronamide + Terbacil 1.68 + 1.12 45cdefg 30abc 37bcd
SpriggiTreatments
Metribuzin 1.12 37bcdef 55bcdef 35bcd
Terbacil 1.12 27abcde 35abcd 37bcd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 20abcd 30abc 22ab
Pronamide/Terbacil 1.68 + 1.12 77h 60cdef 57cde
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

30

of pronamide to stands with low alfalfa densities to decrease total
forage yields, with some increases in alfalfa yield. Pagano et al (24)
also found that metribuzin applied to alfalfa stands with severe weed
pressure reduced total forage yield. Similar results were observed in
this study.

In the 1981 growing season forage yield was either decreased or
unchanged by herbicide treatments at the first cutting (Table 12).
Herbicide treatments either increased or had no effect on alfalfa yield.
Treatments causing reductions in forage yield at the first cutting were
terbacil (1.12 kg/ha) spring applied, pronamide (1.68 kg/ha) fall
applied followed by a spring application of metribuzin (1.12 kg/ha), and
pronamide (1.68 kg/ha) fall applied followed by a spring application of
terbacil (1.12 kg/ha). Treatments causing increases in alfalfa yield at
the first cutting were simazine (1.46 kg/ha) fall applied, pronamide
(1.68 kg/ha) + terbacil (1.12 kg/ha) fall applied, metribuzin (1.12 kg/ha)
spring applied, and terbacil (1.12 kg/ha) spring applied.

In the second and third cuttings there were no significant
differences in either total forage yield or alfalfa yield with any treat-
ments (Tables 13 & 14).

Season total forage yield was decreased by one treatment, but
unaffected by all the others (Table 15). Season total alfalfa yields
for the treated plots were not significantly different from that of the
untreated check.

The treatments which caused a reduction in season total forage
yield were pronamide (1.68 kg/ha) fall applied followed by terbacil
(1.12 kg/ha) Spring applied.

31

 

 

 

 

 

 

Table 12. First harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one in the 1981 growing season.a

Yield
(kg/ha)
Rate Total Broadleaf’
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 3875abc 2058bc 294bc 1523a

Pronamide 1.68 4217abc 2579abc ll4c 1522a

Simazine 1.46 4446abc 3616a 296bc 534bcd

Metribuzin 0.56 5028a 1995bc 2528a 505bcd

Terbacil 1.12 5034a 2405abc l740ab 891abc

Pronamide + Simazine 1.68 + 1.46 3444bc 2716abc 129C 599bcd

Pronamide + Metribuzin 1.68 + 0.56 4301abc 3079ab 264bc 958ab

Pronamide + Terbacil 1.68 + 1.12 4273abc 3450a 365bc 458bcd

Spring Treatments

Metribuzin 1.12 4233abc 2948ab 1235abc 50d

Terbacil 1.12 3276c 3214ab 0c 61d

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 3024c 256labc 259bc 235cd

Pronamide/Terbacil 1.68 + 1.12 l462d 1421c Oc 40d

None 4866ab 1544c 1106ab

2216a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according to
Duncans Multiple Range Test.

32

 

 

 

 

 

 

Table 13. Second harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one in the 1981 growing season.a

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha), Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 1507a 1070a 161a 275a

Pronamide 1.68 1444a 1134a 89a 221a

Simazine 1.46 1657a 1289a 50a 92a

Metribuzin 0.56 2498a 1310a 1014a 169a

Terbacil 1.12 1764a 1293a 186a 135a

Pronamide + Simazine 1.68 + 1.46 1484a 1673a 107a 126a

Pronamide + Metribuzin 1.68 + 0.56 1887a 1251a 79a 135a

Pronamide + Terbacil 1.68 + 1.12 1837a 1209a 511a 117a

Spring Treatments

Metribuzin 1.12 1993a 1651a 283a 59a

Terbacil 1.12 1540a 1439a 26a 74a

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 1769a 1450a 254a 65a

Pronamide/Terbacil 1.68 + 1.12 1585a 1300a 82a 64a

None 1562a 909a 449a 203a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according to

Duncans Multiple Range Test.

33

Table 14. Third harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one in the 1981 growing season.a

 

 

 

 

 

 

Yield
09/ ha)
Rate Total Broadleaf

Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.12 1344a 793a 218a 332a
Pronamide 1.68 1960a 1194a 392a 373a
Simazine 1.46 1394a 921a 257a 216a
Metribuzin 0.56 1573a 828a 508a 236a
Terbacil 1.12 1590a 806a 578a 206a
Pronamide + Simazine 1.68 + 1.46 1344a 879a 192a 273a
Pronamide + Metribuzin 1.68 + 0.56 1388a 803a 378a 207a
Pronamide + Terbacil 1.68 + 1.12 1377a 824a 389a 163a
Spring Treatments
Metribuzin 1.12 1814a 1183a 518a 113a
Terbacil 1.12 1333a 1047a 165a 120a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 1293a 771a 347a 174a
Pronamide/Terbacil 1.68 + 1.12 1574a 1345a 86b 142a
None 1336a 561a 568a 207a

 

SValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

34

 

 

 

 

 

 

Table 15. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site one'hithe 1981
growing season.a

Yield
(kg/ha)
Rate Total
Herbicide (kg/ha) Forage Alfalfa

Fall Treatments

Pronamide 1.12 6726ab 4102a

Pronamide 1.68 7622ab 4900a

Simazine 1.46 7112ab 5834a

Metribuzin 0.56 8512a 4137a

Terbacil 1.12 7045ab 4503a

Pronamide + Simazine 1.68 + 1.46 6272bc 4795a

Pronamide + Metribuzin 1.68 + 0.56 6795ab 5707a

Pronamide + Terbacil 1.68 + 1.12 7487ab 5742a

Springglreatments

Metribuzin 1.12 7474ab 5514a

Terbacil 1.12 6148bc 5702a

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 5869bc 4489a

Pronamide/Terbacil 1.68 + 1.12 4667c 4253a

None 74l4ab 3131a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

35

Several treatments significantly reduced grass yield at the
first cutting (Table 12). The most effective were pronamide (1.68 kg/ha)
fall applied, pronamide (1.68 kg/ha) + simazine (1.46 kg/ha) fall applied,
terbacil (1.12 kg/ha) spring applied, and pronamide (1.68 kg/ha) fall
applied + terbacil (1.12 kg/ha) spring applied. Broadleaf weed yield was
also reduced by several treatments at the first cutting, including metribuzin
(1.12 kg/ha) spring applied, terbacil (1.12 kg/ha) spring applied, pro-
namide (1.68 kg/ha) fall applied + metribuzin (1.12 kg/ha) spring applied
and pronamide (1.68 kg/ha) fall applied + terbacil (1.12 kg/ha) spring
applied. There were no significant reductions in grass or broadleaf
yields from any treatments at the second or third cuttings.

In the 1982 growing season for plots on which separations were
performed, total forage yields at the first harvest were decreased by
all treatments applied in 1981/82 (Table 16). Alfalfa yield was increased
by all treatments except metribuzin (0.56 kg/ha) fall applied. This treat-
ment also showed poor perennial grass and broadleaf control. For plots
which received treatment in 1980/81 and 1981/82, all treatments caused
a reduction in total forage yield at the first cutting (Table 17), how-
ever, only pronamide (1.68 kg/ha) fall applied + metribuzin (1.12 kg/ha)
spring applied caused a significant increase in alfalfa yield at the
first cutting (Table 17). This treatment provided good perennial grass
and broadleaf control at the first cutting. In plots which received
treatment in 1980/81, all treatments except metribuzin (0.56 kg/ha)
fall applied caused a decrease in total forage yield at the first
cutting (Table 18). No treatments resulted in an increase in alfalfa
yield. Although there were reductions in total forage yield, the weed

control obtained from these treatments was not great enough to allow the

36

Table 16. First harvest dry matter yields of total forage, alfalfa,

grass, and broadleaf weeds as influenced by herbicide
treatments at site one in the 1982 growing season for

treatments applied in 1981/823.

 

 

 

 

 

 

Yield
_Lkg/hal
Rate Total Broadleaf

Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 3019ab 2250b 106a 664a
Metribuzin 0.56 3742c 1474a 2161c 106a
Spring Treatments
Metribuzin 1.12 3043ab 2218b 609ab 106a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2694a 2411b 228a 85a
None 4537d 1376a 2498c 663a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

37

Table 17. First harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one in the 1982 growing season. Treat-
ments applied in 1980/81 and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha)_ Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2928a 2250a l93ab 898a
Metribuzin 0.56 -- -- -- --
Spring Treatments
Metribuzin 1.12 2474a 2106a 36lab 7a
Fall/Spripgglreatments
Pronamide/Metribuzin 1.68/1.12 3221a 3201b 2.25a 18a
None 4537b 1376a 2498c 663a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

38

Table 18. First harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for
treatments applied in 1980/81.a

 

 

 

 

 

 

Yield
lkg/haL
Rate Total Broadleaf

Herbicide (kg/ha) Forgge Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 3185ab 1078a 1369ab 651a
Metribuzin 0.56 4117cd 973a 2832c 265a
Sprinngreatments
Metribuzin 1.12 3615bc 1189a 2169bc 258a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2773a 689a 1082a 1002a
None 4537d 1376a 2498c 663a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

39

alfalfa to respond by an increase in growth. At the second and third
cuttings, treatment responses were varied. Total forage yield was
either increased or remained the same. This applied whether results

of treatments in 1981/1982 (Tables 19 and 20), 1980/1981 (Tables 21 and
22) or both years (Tables 23 and 24) are examined. Alfalfa yield either
increased or was unchanged. In most cases, a decrease in total forage
yield corresponded with an increase in alfalfa yield. For this reason,
in the first experiment there were no significant differences in season
total forage yield from any treatments on which separations were per-
formed. Season total alfalfa yield was increased by several treatments.
For treatments which were applied in 1981/82 only pronamide (1.68 kg/ha)
caused an increase in season total alfalfa yield (Table 25). For treat-
ments which were applied in 1980/81 and 1981/82, metribuzin (1.12 kg/ha)
spring applied and pronamide (1.68 kg/ha) fall applied + metribuzin
(1.12 kg/ha) spring applied both resulted in an increase in season total
alfalfa yield (Table 27). There were no significant differences in
alfalfa yield at any cutting or in season total alfalfa yields in 1982
for any treatments which were applied in 1980/81 (Table 26). This is
indicative of the poor weed control observed in 1982 from treatments

which were applied in 1980/81.

Influence of Herbicide Treatments on Forage Quality

 

Dutt (10) found the removal of perennial broadleaf weeds from
established alfalfa had little effect on protein content of the forage.
However, the removal of quackgrass from a severely infested stand signi-
ficantly increased forage protein content. First cutting forage at site

one was infested primarily with orchardgrass and protein content of first

40

Table 19. Second harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for

treatments applied in 1981/82.a

 

 

 

 

 

 

Yield
(kg/hall
Rate Total Broadleaf
Herbicide (kg7ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2386ab 1727b 136a 522b
Metribuzin 0.56 1855a 835a l42b 178a
Spring Treatments
Metribuzin 1.12 2516b 1450b 877b 189a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2350ab 1411b 800b 139a
None 1913a 954a 803b 156a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

41

Table 20. Third harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for
treatments applied in 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Tbtal' Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 1356a 797a 311a 248a
Metribuzin 0.56 1115a 526a 431ab 158a
Spring Treatments
Metribuiin 1.12 l706ab 954a 543ab 209a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2256b 715a 1459c 89a
None 1223a 514a 521ab 187a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

42

Table 21. Second harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for
treatments applied in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide ,(kg/ha)pg Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2119a 788a 941b 390ab
Metribuzin 0.56 2061a 867a 1008b 185a
Spripg Treatments
Metribuzin 1.12 2094a 1083a 773ab 237a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 1825a 855a 372a 598b
None 1913a 954a 803ab 156a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

43

Table 22. Third harvest dry matter yields of total forage, alfalfa,

grass, and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for
treatments applied in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate TOtal Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 1359a 423a 739a 196a
Metribuzin 0.56 1043a 390a 471a 182a
Spring Treatments
Metribuzin 1.12 1584a 527a 917a 140a
Fall/Springglreatments
Pronamide/Metribuzin 1.68/1.12 1182a 306a 678a 197a
None 1223a 514a 521a 187a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

44

Table 23. Second harvest dry matter yields of total forage, alfalfa,
grass, and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growing season for
treatments applied in 1980/81 and 1981/82.

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2250ab 1401ab 262a 587C
Metribuzin 0.56 -- -- -- --
Spripg Treatments
Metribuzin 1.12 2468ab 2115bc 336ab 17a
FalljSpring Treatments
Pronamide/Metribuzin 1.68/1.12 2857b 2695c 137a 29a
None 1913a 954a 803b 156ab

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

45

Table 24. Third harvest dry matter yields of total forage, alfalfa,

grass, and broadleaf weeds as influenced by herbicide
treatments at site one for the 1982 growin
treatments applied in 1980/81 and 1981/82.

g season for

 

 

 

 

 

 

Yield
091/ hal
Rate Totali Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 1113a 645a 144a 344a
Metribuzin 0.56 -- -- -- --
Spring Treatments
Metribuzin 1.12 1633a 849a 630b 125a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2500b 1612b 677b 218a
None 1223a 514a 521b 187a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

46

Table 25. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site one in the
1982 growing season for treatments applied in 1981/82.6

 

 

 

 

 

 

(kg/ haL
Rate Total

Herbicide (kg/ha)p Forage Alfalfa
Fall Treatments
Pronamide 1.68 6750a 4774b
Metribuzin 0.56 6712a 2836a
Sprinngreatments
Metribuzin 1.12 7155a 4622ab
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 7318a 4521ab
None 7943a 2842a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

47

Table 26. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site one for thea
1982 growing season for treatments applied in 1980/81.

 

 

 

 

 

 

Yield
ikg/ ha)
Rate Total'
Herbicide (kg/ha) Forage Alfalfa

Fall Treatments
Pronamide 1.68 6576a 2289a
Metribuzin 0.56 7206a 2230a
Spring Treatments
Metribuzin 1.12 7293a 2800a
Fall/Spring Treatments
Pronamfide/Metribuzin 1.68/1.12 6354a 18666
None 2943a 2842a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

48

Table 27. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site one for the
1982 growing season for treatments applied in 1980/81
and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total
Herbicide ,(kg/ha) Forage Alfalfa

Fall Treatments
Pronamide 1.68 6261a 3832ab
Metribuzin 0.56 -- --
Spring Treatments
Metribuiin 1.12 6576a 5070b
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 8589a 7508c
None 7943a 2842a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

49

cutting forage was found to be significantly higher than the untreated
check for all treatments on which protein analysis was performed in 1981
(Table 28). Of these treatments, metribuzin (1.12 kg/ha) alone or
pronamide (1.68 kg/ha) fall applied followed by a spring application of
metribuzin (1.12 kg/ha) both contained a higher percentage of alfalfa
in the forage (Table 29). The remaining treatments, while not resulting
in an increase in alfalfa yield, did result in a reduction in grass or
broadleaf percentages in the forage, although, these reductions were not
statistically significant. The greatest increase in protein content was
found with pronamide (1.68 kg/ha) fall applied followed by a spring
application of metribuzin (1.12 kg/ha). This treatment resulted in a
forage containing 85.80% alfalfa and 17.11% protein compared to 32.67%
alfalfa and 10.30% protein in the untreated check. The smallest protein
increase resulted from metribuzin (0.56 kg/ha). Forage receiving this
treatment contained 42.28% alfalfa and 13.07% protein. In 1982, all
treatments which resulted in a significant increase in alfalfa percentage
in the forage also resulted in a significant increase in protein content
at the first cutting (Tables 30 and 31). These were all treatments
except metribuzin (0.56 kg/ha) fall applied. There were no differences
between any treatments showing significant protein increases over the
untreated check. The greatest increase in protein content was observed
with pronamide (1.68 kg/ha) fall applied. This treatment resulted in
forage containing 72.99% alfalfa and 17.20% protein compared to 30.21%
alfalfa and 12.78% protein for the untreated check.

Dutt (10) and Fawcett et. a1. (12) both observed increases in
IVDDM as a result of pronamide applications to quackgrass infested

alfalfa, however, there were no significant differences in the IVDMD

50

Table 28. First harvest protein, hivitro digestible dry matter and
acid detergent fiber content of forage at site one in the

1981 growing season.a

 

 

 

 

 

Rate

Herbicide (kg/ha) %P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 16.30a 56.16a 43.77b
Metribuzin 0.56 13.07b 55.79a 43.9lb
Spring Treatments
Metribuzin 1.12 14.97ab 56.35a 43.24b
Fall/Spring Treatments
Pronamide7Metribuzin 1.68/1.12 17.11a 55.05a 41.24b
None 10.30c 52.49a 46.68a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

51

Table 29. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment
at site one in the 1981 growing season.a

 

 

 

 

 

 

%
Rate Broadleaf

Herbicide . (kg/ha), Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 57.86abc 3.23a 38.9lcd
Metribuzin 0.56 42.28ab 47.37b 10.35ab
Spripg Treatments
Metribuzin 1.12 79.33c 19.55ab 1.12a
Fall/Sprjpg Treatments
Pronamide7Metribuzin 1.68/1.12 85.80cd 5.73a 8.47ab
None 32.67a 42.55ab 24.78bc

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

52

Table 30. First harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site one in the

1982 growing season.a

 

 

 

 

 

 

Rate

Herbicide (kg/ha) %P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 17.20a 69.01a 37.23a
Metribuzin 0.56 11.99b 64.25a 40.57a
Spring Treatments
Metribuzin 1.12 17.04a 65.50a 36.65a
Fall/SpripggTreatments
Pronamide/Metribuzin 1.68/1.12 17.18a 65.23a 36.94a
None 12.78b 61.70a 40.25a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according to

Duncans Multiple Range Test.

53

Table 31. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment

at site one in the 1982 growing season.a

 

%

 

 

 

 

 

Rate Broadleaf

Herbicide (kg/ha)__ Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 72.99a 3.4la 23.60b
Metribuzin 0.56 37.13b 60.17c 2.70a
SpripggTreatments
Metribuzin 1.12 74.12a 19.45ab 6.43ab
Fall/Spring Treatments
Pronamide7Metribuzin 1.68/1.12 86.58a 11.50ab 1.92a
None 30.21b 53.74c 16.05ab

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

54

with any treatment at the first cut at site one in either year (Tables
28 and 30).

ADF was significantly decreased by all treatments in 1981 (Table
28) but there were no significant differences in 1982 (Table 30).

There were no significant differences in a protein content,
IVDMD, or ADF at either the second or third cutting at site one in 1981
(Tables 32 and 33) or 1982 (Tables 34 and 35).

55

 

 

 

 

 

 

Table 32. Second harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site one in the
1981 growing season.a
Rate
Herbicide (kg/ha) %P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 19.46a 57.22a 34.18a
Metribuzin 0.56 17.96a 51.9lb 40.40a
Spring_Treatments
Metribuzin 1.12 19.61a 57.29a 34.83a
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 18.96a 56.26a 36.64a
None 18.69a 54.18ab 35.12a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according to
Duncans Multiple Range Test.

56

Table 33. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site one in the

1981 growing season.

 

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 21.27a 61.99a 31.05a
Metribuzin 0.56 20.75a 66.24a 31.69a
Springilreatments
Metribuzin 1.12 21.19a 62.09a 30.74a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 21.13a 61.64a 30.51a
None 21.39a 61.31a 29.63a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according to

Duncans Multiple Range Test.

57

Table 34. Second harvest, in vitro digestible dry matter and acid

detergent fiber content of forage at site one in the

1982 growing season.a

 

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 17.40a 63.69a 32.74a
Metribuzin 0.56 17.22a 64.59a 32.93a
Sprinngreatments
Metribuzin 1.12 17.22a 64.20a 34.05a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 15.87a 63.4la 34.44a
None 16.82a 63.89a 33.07a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

58

Table 35. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site one in the
1982 growing season.a

 

 

 

 

 

 

 

Rate

Herbicide (kg/ha) %P IVDDM ADF
Fall Treatments %DM
PFonamide .68 18.59a 62.48a 26.77a
Metribuzin 0.56 17.33a 58.93a 28.98a
Spripngreatments
Metribuzin .12 16.82a 57.80a 30.27a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 15.27a 59.82a 31.47a
None 17.33a 53.39a 27.88a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

59

SITE II

Weed Control

 

Site 2 was a good stand of alfalfa (56 plants/m2) with relatively
light weed pressure. Weeds present in the stand were dandelion, quack-
grass,white cockle and shepherd's purse. As a result of the good stand
and lower weed pressure, weed control ratings were generally higher at
site 2 than site 1. Quackgrass control at the first cutting was very
good for all treatments except metribuzin (0.56 kg/ha) fall applied and
simazine (1.46 kg/ha)fall applied in 1981 as well as simazine (1.46 kg/ha)
fall applied in 1982 (Tables 36 & 37). Metribuzin (1.12 kg/ha) spring
applied was significantly better than metribuzin (0.56 kg/ha) fall applied
at controlling quackgrass. Quackgrass control at the second and third
cuttings was also very good, although simazine (1.46 kg/ha) fall applied
and metribuzin (0.56 kg/ha) fall applied showed poor control at the
second cutting in 1982. All other treatments provided good control.

For treatments which were applied in both 1980/81 and 1981/82,
all treatments provided good season long quackgrass control in 1982 with
the exception of simazine (1.46 kg/ha) fall applied (Table 38). In
experiment 1 perennial grass control was greatly reduced in 1982 in plots
which were treated only in 1980/81, however, in experiment 2 this was
not the case. All treatments showed good to excellent quackgrass control
throughout the season except metribuzin (0.56 kg/ha) fall applied (Table 39).
These results are in agreement with Fawcett (12) who observed quackgrass
control from pronamide applications to persist into the second year if

applied to stands with high alfalfa populations (40-50 plants/m2).

60

Table 36. Quackgrass control ratings at site two for the 1981 growing

 

 

 

 

 

 

 

season.a
% Control
Rate THarvest
Herbicide (kg/ha) I’ II 111
Fall Treatments
Pronamide 1.12 lOOc 99a 99a
Pronamide 1.68 lOOc 99a 100a
Simazine 1.46 77b 99a 99a
Metribuzin 0.56 71b 63b 68b
Terbacil 1.12 100c 100a 100a
Pronamide + Simazine 1.68 + 1.46 lOOc 100a 100a
Pronamide + Metribuzin 1.68 + 0.56 92bc 100a 100a
Pronamide + Terbacil 1.68 + 1.12 lOOc 100a 100a
Spring Treatments
Metribuzin 1.12 100c 100a 100a
Terbacil 1.12 lOOc 100a 100a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 lOOc 100a 100a
Pronamide/Terbacil 1.68 + 1.12 lOOc 100a 100a
Control 0a Do Do

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

61

 

 

 

 

 

 

 

Table 37. Quackgrass control ratings at site two for the 1982 growing
season. Treatments applied in 1981/82.a
% Control
Rate Harvest
Herbicide (kg/ha)__ I II 111
Fall Treatments
Pronamide 1.12 96cd 73bc 93bcd
Pronamide 1.68 100d 93cde 63b
Simazine 1.46 40ab 47b 73bc
Metribuzin 0.56 76c 50b 70bc
Terbacil 1.12 93cd lOOe 100d
Pronamide + Simazine 1.68 + 1.46 100d 93cde 96cd
Pronamide + Metribuzin 1.68 + 0.56 100d 80cd 93bcd
Pronamide + Terbacil 1.68 + 1.12 96cd 100e 100d
SpripgiTreatments
Metribuzin 1.12 100d 87cde 76bcd
Terbacil 1.12 100d 93cde 100d
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 96cd 96de 93bcd
Pronamide/Terbacil 1.68 + 1.12 96cd lOOe 100d
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

62

 

 

 

 

 

 

 

Table 38. Quackgrass control ratings at site two for the 1982 growing
season. Treatments applied in 1980/81 and 1981/82.a
% Control
Rate Harvest
Herbicide (kg/ha) I II III

Fall Treatments
Pronamide 1.12 100c 93c 96c
Pronamide 1.68 100c 100c 63b
Simazine 1.46 60b 57b 76bc
Pronamide + Simazine 1.68 + 1.46 lOOc 93c 90bc
Pronamide + Metribuzin 1.68 + 0.56 100c 100c 100c
Spring_Treatments
Metribuzin 1.12 100c 100c 100c
Terbacil 1.12 100c 100c 100c
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 100c 100c 96c
Pronamide/Terbacil 1.68 + 1.12 100c 100c 100c
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

63

 

 

 

 

 

 

 

Table 39. Quackgrass control ratings at site two for the 1982 growing
season. Treatments applied in 1980/81.a
% Control
Rate Harvest
Herbicide p(kg/ha)_ I II III
Fall Treatments
Pronamide 1.12 93cd 60bc 73bc
Pronamide 1.68 100d 76cde 90bcd
Simazine 1.46 83bcd 60bc 83bcd
Metribuzin 0.56 53b 37b 53b
Terbacil 1.12 100d 90def 96cd
Pronamide + Simazine 1.68 + 1.46 60b 90def 87bcd
Pronamide + Metribuzin 1.68 + 0.56 73bc 83cde 100d
Pronamide + Terbacil 1.68 + 1.12 100d 93def 86bcd
SpringSTreatments
Matribuzin 1.12 93cd 73cd 86bcd
Terbacil 1.12 100d 90def 100d
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 100d 83cde 80bcd
Pronamide/Terbacil 1.68 + 1.12 100d 96ef 93cd
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

64

Dandelion control at the first cutting in 1981 was very good with
terbacil (1.12 kg/ha) fall or spring applied or with metribuzin (1.12
kg/ha) spring applied (Table 40). Control was also good with these
treatments in combination with pronamide (1.68 kg/ha) fall applied,
however, there were no significant differences between treatments with
or without pronamide. Dandelion control at the second and third cuttings
was similar to the first cutting. Treatments applied in 1981/82 which
gave good dandelion control in 1982 were terbacil (1.12 kg/ha) fall
applied, metribuzin (1.12 kg/ha) spring applied, terbacil (1.12 kg/ha)
spring applied and these treatments in combination with fall applied
pronamide at 1.68 kg/ha (Table 41). All other treatments gave poor
dandelion control.

For treatments which were applied in both 1980/81 and 1981/82,
similar levels of dandelion control were obtained in 1982 (Table 42)
as with the treatments applied in 1981/82 alone (Table 41).

Unlike results observed with quackgrass control at this site,
treatments applied in the fall of 1980 with no subsequent application
showed no better dandelion control than the untreated check in 1982, with
the exception of terbacil (1.12 kg/ha) (Table 43). Treatments applied
in the spring of 1981 were significantly better than the untreated check
at first cutting, but still showed poor dandelion control.

White cockle control was good at the first cutting in 1981 (Table
44) with all treatments except pronamide treatments and simazine (1.46
kg/ha) fall applied and in 1982 with all treatments except pronamide
treatments and metribuzin (0.56 kg/ha) fall applied (Table 45).

Treatments applied in 1980/81 provided poor control in 1982
(Table 46) while treatments applied in both 1980/81 and 1981/82 provided

Table 40. Dandelion control

ratings at site

65

two for the 1981 growing

 

 

 

 

 

 

 

season.a
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 29de 66de 13ef
Pronamide 1.68 0e 69de 13ef
Simazine 1.46 55d 83cd 45cdef
Metribuzin 0.56 51d 66de 49cdef
Terbacil 1.12 89bc 99ab 91ab
Pronamide + Simazine 1.68 + 1.46 50d 61e 35def
Pronamide + Metribuzin 1.68 + 0.56 35de 80de 58cde
Pronamide + Terbacil 1.68 + 1.12 87c 97ab 70bcd
Spring Treatments
Metribuzin 1.12 100a 100a 95ab
Terbacil 1.12 97abc 99a 83abc
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 99ab 94bc 80abc
Pronamide/Terbacil 1.68 + 1.12 100a 100a 98a
Control 0e 0f 0f

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

66

 

 

 

 

 

 

 

Table 41. Dandelion control ratings at site two for the 1982 growing
season. Treatments applied in 1981/82.a
% Control
Rate Harvest

Herbicide (kg/ha) I II 111
Fall Treatments
‘PFOnamide 1.12 0a 0a 0a
Pronamide 1.68 0a 0a 30ab
Simazine 1.46 43ab 57bc 63bc
Metribuzin 0.56 53bc 47b 70bcd
Terbacil 1.12 90de 93f 87cde
Pronamide + Simazine 1.68 + 1.46 57bc 60bcd 67bcd
Pronamide + Metribuzin 1.68 + 0.56 67bcd 60bcd 70bcd
Pronamide + Terbacil 1.68 + 1.12 93dc 86def 83cde
SpringgTreatments
Metribuzin 1.12 lOOe 90f 70bcd
Terbacil 1.12 86cde 87def 77cd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 96e 63bcd 93de
Pronamide/Terbacil 1.68 + 1.12 93de 80cde 87cde
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

67

 

 

 

 

 

 

 

Table 42. Dandelion control ratings at site two for the 1982 growing
season. Treatments applied in 1980/81 and 1981/82.
% Control
Rate Harvest

Herbicide (kg/ha)_ TI II III
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 0a 0a 46b
Simazine 1.46 77bcd 70b 67bcd
Metribuzin 0.56 -- -- --
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 77bcd 77bc 76bcd
Pronamide + Metribuzin 1.68 + 0.56 63b 70b 50bc
Pronamide + Terbacil 1.68 + 1.12 -- -- --
SpringgTreatments
Metribuzin 1.12 lOOe 83bcd 77bcd
Terbacil 1.12 lOOe lOOc 93e
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 lOOe 96dc 87e
Pronamide/Terbacil 1.68 + 1.12 66bc 96dc lOOe
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

68

Table 43. Dandelion control ratings at site two for the 1982 growing
season. Treatments applied in 1980/81.a

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 0a 0a 0a
Simazine 1.46 37abcde 30abcd 57bcd
Metribuzin 0.56 40abcde 23abc 40abc
Terbacil 1.12 33abcd 23abc 57bcd
Pronamide + Simazine 1.68 + 1.46 23abc 43bcde 33ab
Pronamide + Metribuzin 1.68 + 0.56 7ab 30abcd 43abc
Pronamide + Terbacil 1.68 + 1.12 27abc 30abcd 57bcd
Spring_Treatments
Matribuzin 1.12 67cdef 40abcde 60bcd
Terbacil 1.12 70def 50bcdef 73bcde
Fallepring_Treatments
Pronamide/Metribuzin 1.68 + 1.12 50bcde 20ab 47bc
Pronamide/Terbacil 1.68 + 1.12 70def 77fg 73bcde
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

69

 

 

 

 

 

 

 

Table 44. White cockle control ratings at site two for the 1981
growing season. a
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 23de 77bc 66b
Pronamide 1.68 0e 76bc 79ab
Simazine 1.46 40cde 95ab 84ab
Metribuzin 0.56 99a 55c 79ab
Terbacil 1.12 85abc 95ab 97ab
Pronamide + Simazine 1.68 + 1.46 87abc 88ab 86ab
Pronamide + Metribuzin 1.68 + 0.56 Blabc 86abc 97ab
Pronamide + Terbacil 1.68 + 1.12 91ab 94ab 7lab
Spring Treatments
Metribuzin 1.12 97ab 100a 100a
Terbacil 1.12 7lbcd 100a 100a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 80abc 93ab 100a
Pronamide/Terbacil 1.68 + 1.12 66bcd 100a 95ab
Control 0e 0d 0c

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

70

Table 45. First harvest white cockle control ratings at site two
for the 1982 growing season. Treatments applied in
1981/82.a

 

Rate
Herbicide ,(kg/ha) % Control

 

Fall Treatments

 

 

 

Pronamide 1.12 83bcd
Pronamide 1.68 83bcd
Simazine 1.46 73bcd
Metribuzin 0.56 63abc
Terbacil 1.12 96cd
Pronamide + Simazine 1.68 + 1.46 80bcd
Pronamide + Metribuzin 1.68 + 0.56 50ab
Pronamide + Terbacil 1.68 + 1.12 80bcd
Spripg Treatments

Metribuzin 1.12 100d
Terbacil 1.12 96cd
Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 89bcd
Pronamide/Terbacil 1.68 + 1.12 83bcd
Control 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

71

Table 46. First harvest white cockle control ratings at site two for
the 1982 growing season. Treatments applied in 1980/81.a

 

 

 

 

 

Rate

Herbicide (kg/ha) % Control
Fall Treatments
Pronamide 1.12 43abc
Pronamide 1.68 83bcdef
Simazine 1.46 73bcdef
Metribuzin 0.56 33ab
Terbacil 1.12 56abcde
Pornamide + Simazine 1.68 + 1.46 83bcdef
Pronamide + Metribuzin 1.68 + 0.56 66bcdef
Pronamide + Terbacil 1.68 + 1.12 66bcdef
Sprinngreatments
Metribuzin 1.12 56abcde
Terbacil 1.12 50abcd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 57abcde
Pronamide/Terbacil 1.68 + 1.12 76bcdef
Control 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

72

good control (Table 47). White cockle ratings were not made at the second
and third cuttings in 1982 due to sparse populations.

Shepherd's purse control was very good in 1981 with all treatments
except pronamide at 1.12 and 1.68 kg/ha (Table 43). Shepherd's purse was

not rated in 1982 as the infestation was very light.

Influence of Herbicides on Forage Composition and Yield

Pagano (24) and Fortino (14) both observed total forage dry matter
increases as a result of herbicide applications to established stands with
high alfalfa populations. Site two was located in a stand with high alfalfa
populations (40 plants/m2), however, neither forage yield, alfalfa, or
broadleaf yield components were affected by any treatments at the first
cutting in 1981 with the exception of pronamide (1.68 kg/ha) fall applied
and metribuzin (1.12 kg/ha) spring applied which significantly reduced
forage yield (Table 49). However, all treatments except simazine (1.46)
kg/ha) fall applied and metribuzin (0.56 kg/ha) fall applied caused a
significant decrease in grass yield at the first cutting. Few treatments
caused significant yield differences in any component at the second and
third cuttings although grass yields were reduced by several treatments
(Tables 50 & 51). Of the treatments applied in 1981/82 on which botanical
separations were performed, only pronamide (1.68 kg/ha) fall applied
caused a significant decrease in total yield at the first cutting in 1982
(Table 52). There were no significant differences in alfalfa yield at the
first cutting in 1982. All treatments except metribuzin (0.56 kg/ha) fall
applied caused a significant decrease in grass yield at the first cutting
in 1982. There were no differences in broadleaf yield. Total forage yield

was not affected by any treatments at the second cutting (Table 53). Alfalfa

73

Table 47. First harvest white cockle control ratings at site two
Treatments applied in

for the 1982 growing season.
1980/81 and 1981/82.3

 

 

 

 

 

Rate

Herbicide (kg/ha) % Control
Fall Treatments
Pronamide 1.12 66b
Pronamide 1.68 83b
Simazine 1.46 93b
Metribuzin 0.56 -
Terbacil 1.12 -
Pronamide + Simazine 1.68 + 1.46 79b
Pronamide + Metribuzin 1.68 + 0.56 83b
Pronamide + Terbacil 1.68 + 1.12 -
Spring Treatments
Metribuzin 1.12 100b
Terbacil 1.12 lOOb
Fall/SpringgTreatments
Pronamide7Metribuzin 1.68 + 1.12 100b
Pronamide/Terbacil 1.68 + 1.12 lOOb
Control 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

74

Table 48. First harvest shepherd's purse control ratings at site two
for the 1981 growing season.a

 

Rate
Herbicide (kg/ha) % Control

 

Fall Treatments

 

 

 

Pronamide 1.12 40c

Pronamide 1.68 32cd
Simazine 1.46 99ab
Metribuzin 0.56 100a

Terbacil 1.12 100a

Pronamide + Simazine 1.68 + 1.46 95ab
Pronamide + Metribuzin 1.68 + 0.56 90b

Pronamide + Terbacil 1.68 + 1.12 100a

SpringSTreatments

Metribuzin 1.12 100a

Terbacil 1.12 100a

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 100a

Pronamide/Terbacil 1.68 + 1.12 100a

Control 0d

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

75

 

 

 

 

 

 

Table 49. First harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site two in the 1981 growing season.

Yieldi'
lkg/ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 5297a 4309a Ob 1755a

Pronamide 1.68 4547ab 3520a Ob 1027a

Simazine 1.46 6485a 3177a 322ab 2986a

Metribuzin 0.56 6555ab 3999a 231ab 1324a

Terbacil 1.12 4872ab 4214a 0b 657a

Pronamide + Simazine 1.68 + 1.46 4356ab 3680a 0b 677a

Pronamide + Metribuzin 1.68 + 0.56 5398ab 4598a l7lb 629a

Pronamide + Terbacil 1.68 + 1.12 4250ab 3823a Ob 427a

Spring Treatments

Metribuzin 1.12 440lab 4178a Ob 223a

Terbacil 1.12 4273ab 4130a 0b 142a

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 4216ab 4217a Ob 0a

Pronamide/Terbacil 1.68 + 1.12 2789b 2654a 0b 134a

None 5841a 3754a 506a 1580a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

76

 

 

 

 

 

 

Table 50. Second harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site two in the 1981 growing season.a

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 3909a 3672ab 725b 229a

Pronamide 1.68 3590a 3442abc 0b 148a

Simazine 1.46 3757a 3574abc 24b 159a

Metribuzin 0.56 3870a 3067abc 303a 499a

Terbacil 1.12 4401a 4334a 27b 40a

Pronamide + Simazine 1.68 + 1.46 2587a 2305c llb 272a

Pronamide + Metribuzin 1.68 + 0.56 3898a 3720a 0b 177a

Pronamide + Terbacil 1.68 + 1.12 3259a 3156abc 0b 103a

Sprinngreatments

Metribuzin 1.12 4205a 4174a Ob 31a

Terbacil 1.12 3394a 3383abc Ob lla

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 3489a 3398abc 0b 90a

Pronamide/Terbacil 1.68 + 1.12 3461a 3290abc Ob 172a

None 3662a 2363bc 265a 1033a

 

aValues in each column followed

by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

77

Table 51. Third harvest dry matter yields of total forage, alfalfa,

grass and broadleaf weeds as influenced by herbicide
treatments at site two in the 1981 growing season.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf

Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.12 2218a 2105a 5b 107a
Pronamide 1.68 l719cd 1668bc lb 50a
Simazine 1.46 2100abc 206lab 8b 30a
Metribuzin 0.56 2162ab 2065ab 31b 65a
Terbacil 1.12 1831abcd 1775abc 15b 38a
Pronamide + Simazine 1.68 + 1.46 l685d 1641c 0b 66a
Pronamide + Metribuzin 1.68 + 0.56 1848abcd 1833abc 1b 15a
Pronamide + Terbacil 1.68 + 1.12 2049abcd 2023abc lb 26a
SpringiTreatments
Metribuzin 1.12 2083abc 2056ab lb 25a
Terbacil 1.12 2162ab 2153a 0b 9a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 1825abcd l795abc lb 29a
Pronamide/Terbacil 1.68 + 1.12 l881abcd 1849abc lb 31a
None 1809de 1675bc 63a 70a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

Table 52. First harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied

in 1981/82.3

 

 

 

 

 

 

Yield
(kg/ha)
Tbtali Broadleaf
Herbicide Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 3768a 3609a 10a 149a
Metribuzin 4378ab 4000a 574ab 58a
Sprinngreatments
Metribuzin 3785ab 3784a 0a 0a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 4320ab 4295a 6a 19a
None 5021b 3930a 97lb 121a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

79

Table 53. Second harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1981/82.a

 

 

 

 

 

 

Yield
(kg/hale
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 3256a 2979ab 14a 263a
Metribuzin 0.56 2964a 274lab 206a 16a
Spripg Treatments
Metribuzin 1.12 2982a 2913ab 55a 0a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3325a 3308b Oa 17a
None 3192a 2558a 548b 85a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

 

80

Table 54. Third harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1981/82.3

 

 

 

 

 

 

Yield
(k9/ ha)
Rate TotaT’ Broadleaf
Herbicide (kg/ha), Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2336a 1744a 35a 510a
Metribuzin 0.56 2604a 1492a 635cd 477a
SpringgTreatments
Metribuzin 1.12 2532a 1904a 305abc 323a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2905a 2585a 112ab 209a
None 2751a 1759a 795d 197a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

81

yield was increased by pronamide (1.68 kg/ha) fall applied + metribuzin
(1.12 kg/ha) spring applied. Results were similar at the third cutting
(Table 54). .

For treatments applied in both 1980/81 and 1981/82 (Table 55), both
metribuzin (1.12 kg/ha) spring applied and this treatment in combination
with pronamide (1.68 kg/ha) fall applied caused significant decreases in
total forage yield in 1982. There were no differences in total alfalfa
yield. Total forage or alfalfa yield was not affected at the second or
third cuttings by any treatments except pronamide (1.68 kg/ha) fall
applied + metribuzin (1.12 kg/ha) spring applied which caused a signi-
ficant increase in alfalfa yield at the second cutting (Table 56 8 57).
For treatments applied in 1980/81 there were no significant differences
in either total forage yield or alfalfa yield at any cutting in 1982
(Tables 58, 59, 60).

There were no significant differences in either season total forage
yield or season total alfalfa yield from any treatments regardless of
application time in 1981 or 1982 (Tables 61, 62, 63, 64). Before weeds
can cause a reduction in total alfalfa yield they must be dense enough to
compete with the alfalfa for nutrients, water and light. If the weed
pressure is such that this is not occurring, total alfalfa yield will not
increase as a result of weed removal. This appears to have occurred

at the second site.

Influence of Herbicide Treatments on Forage Quality

Protein content was increased at the first harvest by all analyzed

treatments in 1981, except metribuzin (0.56 kg/ha) fall applied (Table 65).

All treatments which increased forage protein percentage also increased

alfalfa percentage, except pronamide (1.68 kg/ha) fall applied (Table 66).

«—-.I

82

Table 55. First harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1980/81 and 1981/82.

 

 

 

 

 

 

Yield
(kg/hat
Rate Tetal Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
PFonamide 1.68 3997abc 3319a 21a 614bc
Spring Treatments
Metribuzin 1.12 3785ab 3785a 0a 0a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3041a 3038a 0a 3a
None 5021c 3930a 97lb 121ab

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

‘I

83

Table 56. Second harvest yield of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1980/81 and 1981/82.

 

 

 

 

 

 

Yield
(kg/ ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Needs

Fall Treatments
Pronamide 1.68 2820a 2494a 7a 320a
Metribuzin 0.56 -- -- -- --
Sprinngreatments
Metribuzin 1.12 3089a 3089abc . 0a 0a
Fall/Spring Treatments
PFonamide/Metribuzin 1.68/1.12 3301a 3217bc 22a 61a
None 3192a 2558a 548b 85a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

84

Table 57. Third harvest yield of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1980/81 and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha
Rate Tota1_’ BroadTeaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2729a 1487a 83ab 1158b
Metribuzin 0.56 -- -- -- --
SpringiTreatments
Metribuzin 1.12 2693a 1882a l65ab 647ab
Fall/Spring Treatments
Pronamide/Metribhzin 1.68/1.12 2682a 1973a 32a 676ab
None 2751a 1759a 795C 197a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

85

Table 58. First harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at
site two for the 1982 growing season for treatments applied
in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Totali Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 4056a 3638a lOa 408ab
Metribuzin 0.56 4551a 3507a 780b 267a
SpringgTreatments
Metribuzin 1.12 4254a 3434a 21a 488ab
Fall/Spripg Treatments
Pronamide/Metribbzin 1.68/1.12 4570a 3701a 38a 831b
None 5021a 3930a 97lb 121a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

86

Table 59. Second harvest yields of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at

site two for the 1982 growing season for treatments applied
in 1980/81.3

 

 

 

 

 

 

Yield
lkg/ ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 3072a 2596ab 0a 475b
Metribuzin 0.56 3219a 2148a 565b 506b
Spring Treatments
Metribuzin 1.12 3200a 2901b 0a 298ab
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2936a 2546ab 5a 385ab
None 3192a 2558ab 565b 85a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

87

Table 60. Third harvest yield of total forage, alfalfa, grass and
broadleaf weeds as influenced by herbicide treatments at

site two for the 1982 growing season for treatments applied
in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total' Broadleaf
Herbicide (kg/ha)! Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2523a 1864a 266ab 392ab
Metribuzin 0.56 2736a 1615a 523bc 599abc
Spring Treatments
Metribuzin 1.12 2828a 1603a 239ab 985bc
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 2657a 1677a 53a 927bc
None 2751a 1759a 795C 197a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

88

 

 

 

 

 

 

Table 61. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site two in the
1981 growing season.a
lkg/ ha)
Rate Total

Herbicide (kg/ha)_ Forage Alfalfa
Fall Treatments
Pronamide 1.12 ll492a 10087a
Pronamide 1.68 9856a 8991a
Simazine 1.46 12343a 8996a
Metribuzin 0.56 11586a 9135a
Terbacil 1.12 11105a 10549a
Pronamide + Simazine 1.68 + 1.46 8651a 8064a
Pronamide + Metribuzin 1.68 + 0.56 lll44a 10151a
Pronamide + Terbacil 1.68 + 1.12 9684a 9280a
Spring_Treatments
Metribuzin 1.12 10690a 10445a
Terbacil 1.12 9828a 10055a
Fall/Spring T tments
Pronamide/Metribuzin 1.68 + 1.12 9506a 9421a
Pronamide/Terbacil 1.68 + 1.12 8116a 7861a
None 11312a 8694a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

89

Table 62. Season total dry matter yields of total forage and alfalfa
as influenced by herbicide treatments at site two in the
1982 growing season. Treatments applied in 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total
Herbicide (kg/ha) Forage Alfalfa

Fall Treatments
Pronamide 1.68 9313a 8333a
Metribuzin 0.56 10199a 8232a
Spripngreatments
Metribuzin 1.12 9284a 8601a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 10550a 10187a
None 10964a 8247a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

90

Table 63. Season total dry matter yields of total forage and alfalfa
as influenced by herbicide treatments at site two in the
1982 growing season. Treatments applied in 1980/81 and

 

 

 

 

 

 

1981/82.a
Yield
llgq/haL
Rate Total—7
Herbicide (kg/ha) Forage Alfalfa
Fall Treatments
Pronamide 1.68 9486a 7104a
Metribuzin 0.56 -- --
Spring Treatments
Metribuzin 1.12 9546a 8735a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 8854a 8062a
None 10964a 8247a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

91

Table 64. Season total dry matter yields of total forage and alfalfa
as influenced by herbicide treatments at site two in the
1982 growing season. Treatments appplied in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total
Herbicide (kg/ha) Forage Alfalfa

Fall Treatments
Pronamide 1.68 9650a 8098a
Metribuzin 0.56 10503a 7269a
Spring_Treatments
Metribuzin 1.12 9969a 7939a
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 lOl63a 7924a
None 10964a 8247a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

92

 

 

 

 

 

 

Table 65. First harvest protein, in vitro digestible dry matter

and acid detergent fiber content of forage at site two

in the 1981 growing season.a

Rate
Herbicide (kg/ha) P IVDDM ADF

Fall Treatments %DM
Pronamide 1.68 16.48a 55.19a 45.93a
Metribuzin 0.56 14.21b 51.8la 51.37a
Spring Treatments
Metfibuzin 1.12 16.59a 52.88a 47.60a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 16.78a 53.47a 46.03a
None 13.34b 53.32a 46.83a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

93

Table 66. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment
at site two in the 1981 growing season. '

 

%

 

 

 

 

 

Rate Broadleaf

Herbicide (kg/ha), Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 84.81abc 0b 15.19ab
Metribuzin 0.56 71.82ab 2.79b 25.39a
Spring_Treatments
Metribuzin 1.12 96.30cd Ob 3.70b
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 100d 0b 0b
None 64.66a 8.37a 26.97a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

94

Between treatments which provided a protein increase over the untreated
check, there was no significant difference in protein content. Forage
treated with pronamide (1.68 kg/ha) fall applied + metribuzin (1.12
kg/ha) spring applied contained 100% alfalfa and 16.78% protein. Forage
from the untreated check contained 64.66% alfalfa and 13.34% protein.
There were no significant differences in protein content between treated
plots and the untreated check at the second and third harvest (Tables 67
and 68). There was no difference in IVDDM or ADF at any cutting in
1981 (Tables 65, 67, 68).

There were no significant differences in percent protein, IVDDM
or ADF with any treatment at any cutting in 1982 (Tables 69, 70, 71).
Although all treatments resulted in forage containing a high percentage
of alfalfa, the forage from the untreated check contained 79.52% alfalfa
and 18.11% protein (Table 72). This high alfalfa percentage and protein
content in the untreated forage resulted in no significant increases in

protein content when weeds were removed by herbicide treatment.

95

Table 67. Second harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site two in the

1981 growing season.a

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 18.07a 57.33a 40.87a
Metribuzin 0.56 18.92a 54.34a 40.67a
Spripngreatments
Metribuzin 1.12 18.40a 58.75a 40.47a
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 17.70a 52.85a 41.13a
None 17.68a 56.39a 40.58a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

96

Table 68. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site two in the

1981 growing season.a

 

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 23.28a 61.96a 30.77a
Metribuzin 0.56 22.51a 61.19a 33.06a
Spripngreatments
Metribuzin 1.12 21.42a 59.12a 33.92a
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 22.93a 61.4la 31.75a
None 22.86a 61.53a 31.13a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

97

 

 

 

 

 

 

 

Table 69. First harvest protein, in vitro digestible dry matter and

acid detergent fiber content of forage at site two

in the 1982 growing season.a

Rate
Herbicide (kg/ha) P IVDDM ADF

Fall Treatments %DM
Pronamide 1.68 17.81a 68.26a 36.77a
Metribuzin 0.56 18.07a 66.10a 37.90a
Spring Treatments
Metribuzin 1.12 18.45a 65.99a 38.05a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 l7.l3a 65.43a 40.12a
None 18.1la 63.40a 35.76a

 

3Values in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

98

Table 70. Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site two

in the 1982 growing season.a

 

 

 

 

 

 

 

Rate

Herbicide (kg/ha)_ P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 16.99a 66.18a 34.27a
Metribuzin 0.56 17.50a 67.44a 33.60a
Spring Treatments
Metribdiih 1.12 18.29a 64.69a 33.51a
Fall/Spring Treatments
Pronamide/Metribuzin? 1.68/1.12 17.67a 66.22a 32.15a
None 18.42a 65.99a 31.78a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

99

Table 71. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site two in the

1982 growing season.a

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 17.10a 66.42a 26.80a
Metribuzin 0.56 17.94a 67.01a 26.79a
Spring Treatments
Metribuzin 1.12 17.15a 65.23a 27.67a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 17.02a 65.34a 28.79a
None 18.83a 66.54a 27.64a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

100

Table 72. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment

at site two in the 1982 growing season.

 

%

 

 

 

 

 

Rate Broadleaf

Herbicide (kg/ha) Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 95.62ab 0.23b 4.15a
Metribuzin 0.56 85.21ab 13.19a 1.26a
Spring Treatments
Metribuiin 1.12 100a 0b 0a
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68/1.12 99.39a 0.16b 0.45a
None 79.52b 18.03a 2.45a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

101

SITE III

Weed Control

 

Experiment 3 was located in a good stand of alfalfa (59 plants/m2)
in which there was severe weed pressure. Weeds present were quackgrass,
dandelion and white cockle. There were several treatments which provided
good quackgrass control in this experiment. Results in 1981 (Table 73)
and 1982 (Table 74) were quite similar. At the first cutting, pronamide
at 1.12 kg/ha and 1.68 kg/ha both provided good quackgrass control.

The two rates were not significantly different. Pronamide (1.68 kg/ha)
fall applied in combination with simazine (1.46 kg/ha), metribuzin

(0.56 kg/ha) or terbacil (1.12 kg/ha) all exhibited good quackgrass
control. However, they were no better than pronmaide alone. Metribu-
zin (0.56 kg/ha) or simazine (1.46 kg/ha) applied alone in the fall did
not provide quackgrass control. Terbacil (1.12 kg/ha) fall applied
alone did give good quackgrass control in 1982 (Table 34). This treat-
ment was not applied in 1981. Although metribuzin (1.12 kg/ha) spring
applied exhibited fair to good quackgrass control at sites one and two,
it did not in this experiment. This is perhaps due to the much heavier
quackgrass stand present at site three as well as a very dry spring in
1982. Terbacil (1.12 kg/ha) spring applied did provide good quackgrass
control. Pronamide (1.68 kg/ha) fall applied followed by a spring
application of either metribuzin (1.12 kg/ha) or terbacil (1.15 kg/ha)
provided good quackgrass control, but no better than the pronamide alone.
Quackgrass control was less in the second and third cuttings for the
majority of the treatments. Pronamide (1.68 kg/ha) fall applied showed
poor quackgrass control in both cuttings in 1982 (Table 34). Control was

improved with this treatment if it was followed by a spring application

102

 

 

 

 

 

 

 

Table 73. Quackgrass control ratings at site three for the 1981
growing season.a
% Control
Rate Harvest
Herbicide (kg/ha) I II 111
Fall Treatments
Pronamide 1.12 99a 89ab 7labc
Pronamide 1.68 100a 7lbcd 80abc
Simazine 1.46 38c 39de 4lcd
Metribuzin 0.56 26c 58cd 49bcd
Terbacil 1.12 —- -- —-
Pronamide + Simazine 1.68 + 1.46 99a 92ab 66abc
Pronamide + Metribuzin 1.68 + 0.56 100a 93ab 6lbcd
Pronamide + Terbacil 1.68 + 1.12 100a 90abc 89abc
Spring Treatments
Metribuzin 1.12 74h 79bc 73abc
Terbacil 1.12 99a 100a 99a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 100a 91a 75abc
Pronamide/Terbacil 1.68 + 1.12 100a 100a 93ab
Control 0d 0e 0d

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

103

 

 

 

 

 

 

 

Table 74. Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1981/82.a
% Control
Rate Harvest

Herbicide _(kg/ha) I II III
Fall Treatments
Pronamide 1.12 94d 70cde 65bcdef
Pronamide 1.68 97d 50bcd 52bcd
Simazine 1.46 32b 22ab 57bcde
Metribuzin 0.56 47bc 42bc 50bc
Terbacil 1.12 87d 75cde 82defgh
Pronamide + Simazine 1.68 + 1.46 100d 85ef 80defgh
Pronamide + Metribuzin 1.68 + 0.56 94d 60bcde 60bcdef
Pronamide + Terbacil 1.68 + 1.12 97d 60bcde 70bcdefg
Spring Treatments
Metribuzin 1.12 65bc 50bcd 45b
Terbacil 1.12 82d 84ef 85efgh
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 100d 77cdef 70bcdefg
Pronamide/Terbacil 1.68 + 1.12 100d 85ef 82defgh
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

104

of either metribuzin or terbacil at 1.12 kg/ha, although this control
was no better than terbacil alone. Metribuzin (1.12 kg/ha) spring
applied provided poor quackgrass control throughout the season in 1982
and only fair control in 1981.

For treatments which were applied in both 1980/81 and 1981/82,
all provided good quackgrass control throughout the season in 1982 ex-
cept simazine (1.46 kg/ha) and metribuzin (1.12 kg/ha) spring applied
(Table 75). These treatments provided only poor to fair control.

For treatments which were applied in 1980/81, few treatments gave
good, season long control in 1982 (Table 76). Terbacil (1.12 kg/ha)
spring applied, or this treatment preceded by a fall application of
pronamide (1.68 kg/ha), gave good quackgrass control in 1982. All other
treatments provided only poor to fair quackgrass control in 1982.

Dandelion control was variable at site 3, but few treatments
gave good consistent control. Pronamide (1.68 kg/ha) fall applied +
metribuzin (1.12 kg/ha) or terbacil (1.12 kg/ha) in the spring provided
the highest levels of dandelion control in 1981 (Table 77) and 1982
(Table 78). All other treatments gave poor to fair control.

Treatments applied in both 1980/81 and 1981/82 appeared to give
slightly better dandelion control in 1982 (Table 79). Compared to the
1982 application alone, those treatments which provided good, season
long dandelion control when applied in both years were metribuzin (1.12
kg/ha) or terbacil (1.12 kg/ha) applied in the Spring. Other treat-
ments provided only fair control.

Of the treatments applied in 1980/81, only pronamide (1.68 kg/ha) +
terbacil (1.12 kg/ha) provided good dandelion control in 1982 (Table 80).

This control decreased toward the end of the season.

105

Table 75. Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1980/81 and

 

 

 

 

 

 

 

1981/82.a
% Control
Rate Harvest

Herbicide (kgjha) 71‘ II III
Fall Treatments
Pronamide 1.12 100c 80cd 75bcd
Pronamide 1.68 84c 82cd 82bcd
Simazine 1.46 l7ab 45b 55b
Metribuzin 0.56 -- -- --
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 100c 85cd 80bcd
Pronamide + Metribuzin 1.68 + 0.56 74c 85cd 92d
Pronamide + Terbacil 1.68 + 1.12 -- ’-- --
Spring Treatments
Metribuzin 1.12 65c 65bc 65bc
Terbacil 1.12 92c 87cd 87cd
FallLSpring Treatments
Pronamide/MetribuZin 1.68 + 1.12 100c 87cd 85cd
Pronamide/Terbacil 1.68 + 1.12 100c 97d 94d
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

106

 

 

 

 

 

 

 

Table 76. Quackgrass control ratings at site three for the 1982
growing season. Treatments applied in 1980/81.a
% Control
Rate Harvest

Herbicide (kglha) I II III
Fall Treatments
Pronamide 1.12 60cdef 50bcde 72cdefg
Pronamide 1.68 67cdefg 45bc 57bcde
Simazine 1.46 l7ab l7ab 20ab
Metribuzin 0.56 37bc 52bcde 65cdef
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 52cde 37abc 57bcde
Pronamide + Metribuzin 1.68 + 0.56 42de 47bcd 55bcd
Pronamide + Terbacil 1.68 + 1.12 69cdefg 57bcdef 57bcde
Spring Treatments
Metribuzin 1.12 42de 35abc 40bc
Terbacil 1.12 1009 77defg 85efgh
Fall/Spripg Treatments
Pronamide/Metribuzin 1.68 + 1.12 70cdefg 57bcdef 70cdefg
Pronamide/Terbacil 1.68 + 1.12 979 87fg 85efgh
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

107

 

 

 

 

 

 

 

Table 77. Dandelion control ratings at site three for the 1981 growing
season.a
% Control
Rate Harvest

Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 Og 25f 29cd
Pronamide 1.68 Og 33ef 5d
Simazine 1.46 28f 48de 25cd
Metribuzin 0.56 51de 69bc 67ab
Terbacil 1.12 -- -- ~-
Pronamide + Simazine 1.68 + 1.46 42e 56cd 48bc
Pronamide + Metribuzin 1.68 + 0.56 09 48de 20cd
Pronamide + Terbacil 1.68 + 1.12 58d 75ab 74a
Spring Treatments
Metribuzin 1.12 70c 7lbc 48bc
Terbacil 1.12 81b 75ab 6lab
Fall/Spring Treatments
Pronamide7MetriBUZIn 1.68 + 1.12 80b 81ab 62ab
Pronamide/Terbacil 1.68 + 1.12 90a 85a 76a
Control 09 09 0d

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

108

 

 

 

 

 

 

 

Table 78. Dandelion control ratings at site three for the 1982
growing season. Treatments applied in 1981/82.a
% Control
Rate Harvest

Herbicide (kg/ha) II II III
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 0a 5a 0a
Simazine 1.46 57bcd 60bcde 57b
Metribuzin 0.56 50bc 47bc 70bcd
Terbacil 1.12 65cde 60bcde 70bcd
Pronamide + Simazine 1.68 + 1.46 42bc 62bcde 65bc
Pronamide + Metribuzin 1.68 + 0.56 27ab 37b 65bc
Pronamide + Terbacil 1.68 + 1.12 65cde 70cdef 72bcd
Spring Treatments
Metribuzin 1.12 70cde 52bcd 62bc
Terbacil 1.12 67cde 57bcd 67bcd
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 87ef 87fg 72bcd
Pronamide/Terbacil 1.68 + 1.12 85def 87fg 82de
Control 0a 0a 0a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

109

Table 79. Dandelion control ratings at site three for the 1982 growing
season. Treatments applied in 1980/81 and 1981/82.a

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) I II III
Fall Treatments
Pronamide 1.12 l7ab 20ab Oa
Pronamide 1.68 0a 0a 0a
Simazine 1.46 62cd 70c 67b
Metribuzin 0.56 -- -- --
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 67cde 75c 72b
Pronamide + Metribuzin 1.68 + 0.56 47bc 75c 70b
Pronamide + Terbacil 1.68 + 1.12 -- -- --
Spring Treatments
Metribuzin 1.12 94f 87d 77c
Terbacil 1.12 62cd 80c 77c
Fall/Spring Treatments
Pronamide7Metribuzin 1.68 + 1.12 89ef 72c 77c
Pronamide/Terbacil 1.68 + 1.12 94f 94d 87c
Control 0a 0a 0a

 

aValuesineach column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

110

Table 80. Dandelion control ratings at site three for the 1982
growing season. Treatments applied in 1980/81.3

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha) I II 111
Fall Treatments
Pronamide 1.12 0a 0a 0a
Pronamide 1.68 15abc 0a 0a
Simazine 1.46 lOab 20ab 40bc
Metribuzin 0.56 47bcd 42bcde 47bcdef
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 57de 40bcde 45bcde
Pronamide + Metribuzin 1.68 + 0.56 15abc 22ab 32b
Pronamide + Terbacil 1.68 + 1.12 45bcd 40bcde 45bcde
Spring_Treatments
Metribuzin 1.12 57de 25abc 42bcd
Terbacil 1.12 47bcd 50cdef 50bcdefg
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 47bcd 35bcd 47bcdef
Pronamide/Terbacil 1.68 + 1.12 85ef 72fg 57cdefgh
Control 0a 03 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

111

White cockle control was good in 1981 (Table 81) and 1982 (Table
82) with metribuzin or terbacil spring applied at 1.12 kg/ha or these
treatments in combination with fall applied pronamide. Although, control
with the treatments including pronamide was no better than those without.
No other treatments provided good control in both 1981 and 1982. Results
were similar in 1982 for treatments which were applied in both 1980/81
and 1981/82 (Table 83) and treatments applied in 1980/81 (Table 84).
The 1980/81 treatments provided somewhat less control. The reduction
in white cockle control with these treatments was not as severe as that

observed with quackgrass or dandelion.

Influence of HerbicidescniForage Composition and Yield

 

Pronamide (1.68 kg/ha) fall applied + terbacil (1.12 kg/ha)
spring applied significantly reduced total forage yield at the first
cutting in 1981 at site 3 (Table 85). None of the other treatments
effected forage yield. Alfalfa yield at the first cutting was signi—
ficantly increased by several treatments including: metribuzin (0.56
kg/ha) fall applied; pronamide (1.68 kg/ha) + terbacil (1.12 kg/ha)
fall applied; metribuzin (1.12 kg/ha) spring applied; terbacil (1.12
kg/ha) spring applied; and pronamide (1.68 kg/ha) fall applied + met-
ribuzin (1.12 kg/ha) spring applied. Only metribuzin (0.56 kg/ha) fall
applied affected grass yield. This treatment had higher grass yield
compared to the untreated check. This could be caused by a reduction
in broadleaf weed competition provided by the treatment combined with
very little grass control at this low rate. This would allow the grass
yield to increase.

Several treatments caused signifcant reductions in broadleaf weed

yield at the first cutting. The most effective were pronamide (1.68 kg/ha)

112

Table 81. White cockle control ratings at site three for the 1981
growing season.a

 

 

 

 

 

 

 

% Control
Rate Harvest
Herbicide (kg/ha)_ I II III
Fall Treatments
Pronamide 1.12 0d 73cd 99a
Pronamide 1.68 0d 65cd 87a
Simazine 1.46 85ab 82bcd 100a
Metribuzin 0.56 62bc 83bcd 88a
Terbacil 1.12 -- -- --
Pronamide + Simazine 1.68 + 1.46 50c 87abc 97a
Pronamide + Metribuzin 1.68 + 0.56 0d 55d 92a
Pronamide + Terbacil 1.68 + 1.12 82ab 86abcd 91a
Spring Treatments
Metribuzin 1.12 91a 99a 87a
Terbacil 1.12 86ab 97ab 93a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 85ab 9labc 97a
Pronamide/Terbacil 1.68 + 1.12 73abc 97ab 95a
Control 0d 0e Ob

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

113

Table 82. First harvest white cockle control ratings at site three
for the 1982 growing season. Treatments applied in

 

1981/82.3
Rate
Herbicide (kglha)_ % Control

 

Fall Treatments

 

 

 

Pronamide 1.12 75bcde
Pronamide 1.68 46bc
Simazine 1.46 72bcde
Metribuzin 0.56 57bcde
Terbacil 1.12 52bcd
Pronamide + Simazine 1.68 + 1.46 42b
Pronamide + Metribuzin 1.68 + 0.56 65bcde
Pronamide + Terbacil 1.68 + 1.12 80bcde
SpringSTreatments

Metribuzin 1.12 92de
Terbacil 1.12 65bcde
Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 92de
Pronamide/Terbacil 1.68 + 1.12 84bcde
Control 0a

 

aValues in each column followed
significantly different at the 0.05
to Duncans Multiple Range Test.

by the same letter are not
level of probability according

114

 

 

 

 

 

Table 83. First harvest white cockle control ratings at site three
for the 1982 growing season. Treatments applied in
1980/81 and 1981/82.a .
Rate
Herbicide (kg/ha) % Control
Fall Treatments
Pronamide 1.12 60bc
Pronamide 1.68 65bc
Simazine 1.46 77bc
Metribuzin 0.56 --
Terbacil 1.12 --
Pronamide + Simazine 1.68 + 1.46 75bc
Pronamide + Metribuzin 1.68 + 0.56 50b
Pronamide + Terbacil 1.68 + 1.12 --
Sprinngreatments
Metribuzin 1.12 97c
Terbacil 1.12 100c
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 97c
Pronamide/Terbacil 1.68 + 1.12 97c
Control 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

115

Table 84. First harvest white cockle control ratings at site three
for the 3982 growing season. Treatments applied in

1980/81.

 

 

 

 

 

Rate

Herbicide (kg/ha) % Control
Fall Treatments
Pronamide 1.12 55bcde
Pronamide 1.68 57bcde
Simazine 1.46 27ab
Metribuzin 0.56 64bcde
Terbacil 1.12 --
Pronamide + Simazine 1.68 + 1.46 62bcde
Pronamide + Metribuzin 1.68 + 0.56 37abc
Pronamide + Terbacil 1.68 + 1.12 50bcd
Spripg Treatments
Metribuzin 1.12 80cde
Terbacil 1.12 84de
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 70bcde
Pronamide/Terbacil 1.68 + 1.12 89de
Control 0a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

116

 

 

 

 

 

 

Table 85. First harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide treat-
ments at site three in the 1981 growing season.a

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kgjha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 5365a 280labc 36c 2528ab

Pronamide 1.68 4654a 2332bc 535ab l786abc

Simazine 1.46 5040a 2850abc 581ab l608bc

Metribuzin 0.56 5185a 3763ab 806a 617de

Terbacil 1.12 -- -- -- --

Pronamide + Simazine 1.68 + 1.46 4457a 3247abc 26c ll85cd

Pronamide + Metribuzin 1.68 + 0.56 4771a 2984abc 20c 1815abc

Pronamide + Terbacil 1.68 + 1.12 4833a 394lab 0c 892cde

SpringgTreatments

Matribuzin 1.12 5185a 347lab 36lbc 260de

Terbacil 1.12 4513a 4209a 0c 304de

Fall/Spring Treatments

Pronamide/Metribuzin 1.68 + 1.12 4530a 4409a 0c 121e

Pronamide/Terbacil 1.68 + 1.12 2940b 2868abc 14c 57e

None 4754a 1804c 266bc 2684a

 

aValues in each column followed

by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

117

fall applied + metribuzin (1.12 kg/ha) spring applied and pronamide
(1.68 kg/ha) fall applied + terbacil (1.12 kg/ha) spring applied.
Treatments with no reduction in broadleaf weed yields were pronamide
(1.12 kg/ha or 1.68 kg/ha) fall applied and pronamide (1.68 kg/ha) +
metribuzin (0.56 kg/ha) fall applied.

Total forage, grass, and broadleaf weed yields were not affected
by any treatments at the second cutting (Table 86). No treatments
produced significant alfalfa yield increases over the untreated check,
but there were differences between some treatments. At the third cutting,
no treatments effected total forage, alfalfa, grass, or broadleaf weed
yield (Table 87).

There were no significant effects on season total forage yields
from any treatnents compared to the untreated check in 1981, but several
treatments showed significant increases in season total alfalfa yield
(Table 88).

Unlike 1981, in 1982 none of the treatments applied only in 1981/82
significantly affected total forage yield or alfalfa yield at the first
(Table 89), second (Table 90), or third harvests (Table 91). Similarly,
season total forage or season total alfalfa yield was not significantly
changed by any herbicide treatment in 1982 except spring applied metri-
buzin (Table 92). Season total alfalfa yield was significantly increased
by a spring application of metribuzin (1.12 kg/ha).

Treatments applied in 1980/81 also did not affect total forage
yield or alfalfa at any of the three harvests (Tables 93, 94, and 95).
Season total forage yield and season total alfalfa yield also were not
altered in 1982 tn! the treatments in 1980/81 (Table 96).

Metribuzin (1.12 kg/ha) spring applied and pronamide (1.68 kg/ha)
fall applied + metribuzin (1.12 kg/ha) spring applied both caused

118

 

 

 

 

 

 

Table 86. Second harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide treat-
ments at site three in the 1981 growing season.

Yield
(kg/hal
Rate TotaTI' Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 1803a 1004e 73a 726a

Pronamide 1.68 2001a l476abcde 20a 505a

Simazine 1.46 1770a 1118de 291a 360a

Metribuzin 0.56 3270a 2560a 188a 521a

Terbacil 1.12 -- -- -- --

Pronamide + Simazine 1.68 + 1.46 2744a 2175abc 8a 561a

Pronamide + Metribuzin 1.68 + 0.56 2576a 1816abcde 27a 732a

Pronamide + Terbacil 1.68 + 1.12 2391a 1899abcde 12a 480a

Sprinngreatments

Metribuzin 1.12 3080a 2741a 79a 259a

Terbacil 1.12 2687a 234lab 0a 347a

Fall/Spripg Treatments

Pronamide/Metribuzin 1.68 + 1.12 2655a 2092abcd 25a 537a

Pronamide/Terbacil 1.68 + 1.12 2262a 127lcde 946a 44a

None 2139a l364abcde 33a 741a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

119

 

 

 

 

 

 

Table 87. Third harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1981 growing season.a

(kg/ ha)
Rate Total Broadleaf
Herbicide p(kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments

Pronamide 1.12 1798a 1213a 360a 224a

Pronamide 1.68 2094a 1687a 141a 266a

Simazine 1.46 2156a 1759a 95a 302a

Metribuzin 0.56 1853a 1162a 69a 615a

Terbacil 1.12 -- -- -- --

Pronamide + Simazine 1.68 + 1.46 2946a 2513a 10a 422a

Pronamide + Metribuzin 1.68 + 0.56 2046a 1709a 5a 331a

Pronamide + Terbacil 1.68 + 1.12 1898a 1681a 2a 215a

Spring_Treatments

Matribuzin 1.12 2385a 2068a 133a 184a

Terbacil 1.12 2162a 2009a 9a 143a

FallLSpripg Treatments

Pronamidé/Metribuzin 1.68 + 1.12 2385a 2068a 83a 273a

Pronamide/Terbacil 1.68 + 1.12 1792a 1664a 7a 133a

None 1657a 1441a 46a 170a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

120

Table 88. Season total dry matter yields of forage and alfalfa
as influenced by herbicide treatments at site three
in the 1981 growing season.a

 

 

 

 

 

 

Yield
lkg/ha)
Rate TotaT

Herbicide (kg/ha) Forage Alfalfa
Fall Treatments
PronamideI’ 1.12 8966ab 4917f
Pronamide 1.68 8749ab 5580ef
Simazine 1.46 8966ab 5751def
Metribuzin 0.56 10309a 7988abc
Terbacil 1.12 -- ~-
Pronamide + Simazine 1.68 + 1.46 10147a 7855abc
Pronamide + Metribuzin 1.68 + 0.56 9393a 6530cdef
Pronamide + Terbacil 1.68 + 1.12 8966ab 7590abcd
Spring Treatments
Metribuzin 1.12 10651a 9211a
Terbacil 1.12 9363a 8427abc
Fall/Spring Treatments
Pronamide/Metribuzin 1.68 + 1.12 9571a 8789ab
Pronamide/Terbacil 1.68 + 1.12 6994b 6967bcde
None 8551ab 5262ef

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

121

Table 89. First harvest dry matter yields of total forage, alfalfa,

grass and broadleaf weeds as influenced by_herbicide

treatments at site three in the 1982 growing season for

treatments applied in 1981/82.a

 

 

 

 

 

 

lkg/ ha )
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 4204a 3645a 33a 526a
Metribuzin 0.56 4210a 2849a 704a 656a
SpringgTreatments
Metribuzin 1.12 4183a 3687a 225a 257a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3274a 3128a 23a 122a
None 4215a 2452a 388a 1374a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

122

Table 90. Second harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for

treatments applied in 1981/82.a

 

 

 

 

 

 

Yield
(ktha) _r
Rate Total Broadleaf
Herbicide _(kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2975ab 2169ab 1067a 374ab
Metribuzin 0.56 2577a 1770a 548a 259a
Spring_Treatments
Metribuzin 1.12 3033ab 2393ab 309a 330ab
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3371b 268lbc 464a 228a
None 2890ab 1896ab 344a 599b

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

123

Table 91. Third harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for
treatments applied in 1981/82.

 

 

 

 

 

 

Yield
(kg/ha)
Rate Tetal Broadleaf
Herbicide (kg/ha)_, Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2291a 1636a 211a 444a
Metribuzin 0.56 2374a 1777a 245a 351a
SpringgTreatments
Metribuzin 1.12 2583a 2131a 165a 287a
Fall/Spring Treatments
Pronamide/Metribuiin 1.68/1.12 2369a 1918a 111a 339a
None 2600a 1789a 156a 655a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

124

Table 92. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site three in the
1982 growing season for treatments applied in 1981/82.a

 

 

 

 

 

 

Rate Total

Herbicide (kg/ha), Forage Alfalfa
Fall Treatments
PFonamide 1.68 10223a 7453ab
Metribuzin 0.56 9056a 6391ab
Spring Treatments
Metribuzin 1.12 9761a 8211b
FalllSpripg Treatments
Pronamide/Metribuzin 1.68/1.12 9067a 7728ab
None 9448a 5916a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

125

Table 93. First harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for
treatments applied in 1980/81.6

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 4088a 2127a 983ab 978a
Metribuzin 0.56 3613a 1912a 1218b 483a
Spripg Treatments
Metribuzin’ 1.12 4026a 2615a 84lab 570a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3974a 2917a 532ab 524a
None 4215a 2452a 388a 1374a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

126

Table 94. Second harvest dry matter yields of total forage, alfalfa,

grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for

treatments applied in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha)¥ Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2528a 1678a 372a 478a
Metribuzin 0.56 2653a 1971a 375a 307a
Spring_Treatments
Metribuzin 1.12 2748a 1762a 502a 444a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2802a 2189a 177a 435a
None 2890a 1896a 344a 599a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

127

Table 95. Third harvest dry matter yields of total forage, alfalfa,

grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for

treatments applied in 1980/81.a

 

 

 

 

 

 

(kg/ha)
Rate Total Broadleaf

Herbicide (kg/ha) Forage Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 2143a 1222a 438a 483a
Metribuzin 0.56 2652a 1700a 275a 676a
Spripgilreatments
Metribuzin' 1.12 2433a 1640a 288a 505a
Fall/SpringgTreatments
Pronamide/Metribuzin 1.68/1.12 2431a 1776a 282a 380a
None 2600a 1789a 156a 655a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

128

Table 96. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site three in the
1982 growing season for treatments applied in 1980/81.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total
Herbicide (kg/ha) Forage Alfalfa

Fall Treatments
Pronamide 1.68 8760a 5027a
Metribuzin 0.56 8926a 5591a
Spring Treatments
Metribuzin 1.12 9029a 6004a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 9213a 6883a
None 9448a 5916a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

129

significant alfalfa yield increases when applied in both 1980/81 and
1981782 (Table 97). This effect did not persist into the second harvest
(Table 98). At the second cutting, there were no effects on total forage
yield or alfalfa yield for any treatments except pronamide (1.68 kg/ha)
fall applied + metribuzin (1.12 kg/ha) spring applied which caused a
significant increase in alfalfa yield. The same was true at the third
cutting (Table 99). Season total alfalfa yield was significantly increased
by pronamide (1.68 kg/ha) fall applied + metribuzin (1.12 kg/ha) spring
applied in both 1980/81 and 1981/82 and by metribuzin (1.12 kg/ha) applied
in the spring of 1981 and again in the spring of 1982 (Table 100).

Influence of Herbicide Treatments on Forage Quality

 

Only pronamide (1.68 kg/ha) fall applied + metribuzin (1.12 kg/ha)
spring applied resulted in a significant protein increase in the forage
at the first cutting in 1981 (Table 101). This treatment also resulted
in the largest increase in forage alfalfa content (Table 102). Forage
receiving this treatment contained 97.10% alfalfa and 19.46% protein.
Forage from the untreated check contained 37.39% alfalfa and 16.29%
protein. There were no significant differences in protein content at
either the second (Table 103) or third (Table 104) harvests in 1981.
There also were no differences in IVDMD or ADF content at any cutting
at this site in 1981 (Tables 101, 103, 104).

In 1982, pronamide (1.68 kg/ha) fall applied and this treatment
followed by a spring application of metribuzin (1.12 kg/ha) both resulted
in a significant increase in forage protein content (Table 105). Both
treatments also resulted in an increase in alfalfa percentage in the

forage (Table 106). Metribuzin (1.12 kg/ha) spring applied also resulted

130

Table 97. First harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for
treatments applied in 1980/81 and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Total ’Broadleaf
Rate (kg/ha)_ Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 4329a 3234ab 8a 847a
Metribuzin -- -- -- --
Spring Treatments
Metribuzin 4749a 4201b 511a 36a
Fall1$pring Treatments
Pronamide/Metribuzin 1.68/1.12 4109a 4043b 3a 62a
None 4215a 2452a 388a 1374a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

"1

131

Table 98. Second harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for
treatments applied in 1980/81 and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total Broadleaf
Herbicide (kg/ha) Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2885a 2228a 5a 652b
Metribuzin 0.56 -- -- -- --
Spripngreatments
Metribuzin' 1.12 3074a 253lab 531a 11a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 3326a 3299b 5a 20a
None 2890a 1896a 534a 599b

 

aValues in each column followed by the same letter are not
signficantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

132

Table 99. Third harvest dry matter yields of total forage, alfalfa,
grass and broadleaf weeds as influenced by herbicide
treatments at site three in the 1982 growing season for
treatments applied in 1980/81 and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total' Broadleaf
Herbicide (kg/ha)_ Forage Alfalfa Grass Weeds

Fall Treatments
Pronamide 1.68 2733a 2180ab 14a 539a
Metribuzin 0.56 -- -- -- --
Spring Treatments
Metribuzin 1.12 2774a 2302ab 339a 132a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 2765a 2591b 11a 163a
None 2600a 1789a 156a 655a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

133

Table 100. Season total dry matter yields of forage and alfalfa as
influenced by herbicide treatments at site three in the
1982 growing season for treatments applied in 1980/81
and 1981/82.a

 

 

 

 

 

 

Yield
(kg/ha)
Rate Total
Herbicide (kg/ha)_ Forage Alfalfa

Fall Treatments
Pronamide 1.68 9947a 7642ab
Metribuzin 0.56 -- --
Spripg Treatments
Metribuzin 1.12 10596a 9035bc
Fall/Spripg Treatments
Pronamide/Metfibuzin 1.68/1.12 10199a 9933c
None 9448a 5916a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

134

Table 101. First harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site three in

the 1981 growing season.a

 

 

 

 

 

 

Rate
Herbicide (kg/ha)_ P IVDDM ADF
%DM

Fall Treatments
Pronamide 1.68 15.80c 59.73a 43.60a
Metribuzin 0.56 16.00c 57.64a 43.00a
Spring Treatments
Metribuzin 1.12 18.55ab 58.12a 43.29a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 19.46a 59.30a 41.04a
None 16.29bc 61.09a 41.79a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

1mm

135

Table 102. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment
at site three in the 1981 growing season.

 

%

 

 

 

 

 

Rate Broadleaf

Herbicide (kg/ha) Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 50.95ab 10.85ab 38.20b
Metribuzin 0.56 71.74bc 15.50a 12.76bc
Spripg Treatments
Metribuzin 1.12 85.18cd 7.08bc 7.74bc
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 97.10e Oc 2.90c
None 37.39a 5.65bc 56.96a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

136

Table 103. Second harvest protein,irivitro digestible dry matter and
acid detergent fiber content of forage at site three in

the 1981 growing season.a

 

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 17.08a 58.07a 36.65a
Metribuzin 0.56 16.34a 55.83a 39.99a
Sprinngreatments
Metribuzin 1.12 17.47a 56.30a 37.31a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 18.36a 54.78a 38.51a
None 15.95a 55.37a 40.53a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

137

Table 104. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site three in

the 1981 growing season.3

 

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 20.32a 60.7la 35.77a
Metribuzin 0.56 22.00a 64.85a 32.99a
Spring Treatments
Metribuzin 1.12 21.75a 62.46a 35.94a
Fall/Spring Treatments
PFonamide/Metribuzin 1.68/1.12 21.80a 61.20a 34.33a
None 21.57a 66.3la 35.14a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

 

138

Table 105. First harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site three in

the 1982 growing season.a

 

 

 

 

 

Rate

Herbicide (kg/ha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 18.45ab 70.26a 34.61abc
Metribuzin 0.56 16.67c 67.37a 36.39ab
Spring Treatments
Metribuzin 1.12 17.17bc 67.02a 36.63a
FalllSpring Treatments
Pronamide7Metribuzin 1.68/1.12 19.01a 67.15a 34.27bc
None 16.22c 68.38a 33.64c

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

139

Table 106. Percent alfalfa, grass and broadleaf weeds present in
first harvest forage as influenced by herbicide treatment
at site three in the 1982 growing season.a

 

 

 

 

 

 

 

%
Rate Broadleaf
Herbicide (kg/ha) Alfalfa Grass Weeds
Fall Treatments
Pronamide 1.68 87.31bc 0.75a 11.94a
Metribuzin 0.56 68.30ab 15.87a 15.83a
Spring Treatments
Metribuzin 1.12 87.83bc 5.96a 6.21a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 95.85c 0.69a 3.46a
None 59.95a 9.6la 30.44a

 

aValues in each column followed by the same letter are not
significantly different at the 0.05 level of probability according
to Duncans Multiple Range Test.

140

in an increase in forage alfalfa content. This resulted in an increase
in a forage protein increase, but this increase was not significant.
Forage treated with metribuzin (0.56 kg/ha) fall applied did not contain
significantly more alfalfa or protein than the untreated check. Protein
content of forage at the second (Table 107) and third (Table 108) cutting
was not affected by herbicide treatments.

IVDMD was not affected at site 3 in 1982 by any treatments at
any of the three cuttings (Tables 105, 107, 108). ADF content of first
cutting forage in 1982 was significantly increased by applications of
metribuzin at 0.56 kg/ha fall applied and 1.12 kg/ha spring applied.

No other treatments at any cutting had an effect on ADF content.

 

141

Table 107. Second harvest protein, in vitro digestible dry matter
and acid detergent fiber content of forage at site three

in the 1982 growing season.a

 

 

 

 

 

 

Rate

Herbicide (kglha) P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 19.36a 62.76a 31.83b
Metribuzin 0.56 17.90a 63.23a 32.50b
SpringATreatments
Metribuzin 1.12 18.43a 61.30a 35.36ab
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 18.67a 59.35a 37.39a
None 18.78a 61.08a 34.20ab

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

 

 

 

142

Table 108. Third harvest protein, in vitro digestible dry matter and
acid detergent fiber content of forage at site three in

the 1982 growing season.

 

 

 

 

 

 

Rate

Herbicide (kg/ha)_ P IVDDM ADF
Fall Treatments %DM
Pronamide 1.68 19.20a 63.38a 30.62a
Metribuzin 0.56 18.65a 52.06a 31.37a
Spring Treatments
Metribuzin 1.12 18.62a 45.47a 31.75a
Fall/Spring Treatments
Pronamide/Metribuzin 1.68/1.12 19.20a 46.81a 30.94a
None 18.89a 53.24a 30.38a

 

aValues in each column followed by the same letter are not

significantly different at the 0.05 level of probability according

to Duncans Multiple Range Test.

 

 

‘34.? ,,.E.L- L'..' I:

 

GENERAL DISCUSSION

Several general conclusions can be drawn from this research.
In terms of weed control efficacy, the herbicide treatments can be
grouped into four categories. Metribuzin (0.56 kg/ha) fall applied,
terbacil (1.12 kg/ha) fall applied, and simazine (1.40 kg/ha) fall
applied all provided control of annual broadleaf weeds, but little control
of perennial broadleaves or grasses. Pronamide (1.68 kg/ha) fall applied
effectively controlled perennial grasses, but had little or no effect
on broadleaf weeds. Spring applications of metribuzin or terbacil at
1.12 kg/ha controlled both annual and perennial broadleaf weed species
and had a significant effect on perennial grasses. A combination of
fall applied pronamide (1.68 kg/ha), followed by a spring application
of either metribuzin or terbacil at 1.12 kg/ha, provided nearly 100%
control of both perennial and annual broadleaf and grass species.

Longevity of control from all treatments was poor. Plots which
received treatment in 1980/81 with no subsequent application in 1981/82
showed poor weed control in the 1982 growing season. Plots which re-
ceived treatments in 1980/81 and a second application in 1981/82 showed
control in 1982 similar to, but no better than, control in 1981.

Weed control measures were most effective at site II which con-
sisted of a good stand of alfalfa with light weed pressure. At this

site, the dense stand of alfalfa was very competitive with the weeds

1.43

 

144

present which aided in weed control. Also, the alfalfa was better able
to compete with weeds for open spaces created by the weed control meas-
ures. Weed pressure at sites one and three was severe. Weed control
at these two sites was similar, although site one was located in a very
sparse stand of alfalfa. Weed control at this site resulted in empty
spaces which were filled in by weeds not controlled by the application
treatment. Controlling perennial grasses resulted in an increase in
broadleaf weeds and vis a verse.

Yield effects from herbicide treatments were observed most
dramatically at the first cutting. First cutting forage yields were
either reduced or not affected by herbicide treatments. Reductions in
forage yield were due to herbicide treatments which removed the weedy
component of the forage. Alfalfa yield either increased or remained
the same at the first cutting. The effects of herbicide treatments on
season total yields were similar to first cutting results. Season total
forage yields either decreased or remained the same while season total
alfalfa yields either increased or remained the same. As at the first
cutting, treatments which caused decreases in total forage yield did so
by removing the Weed component from the forage. Treatments which pro—
vided poor weed control resulted in total forage yields which were not
significantly lower than the untreated check due to little or no re-
duction in the weed component of the forage. Treatments which provided
excellent weed control could also result in total forage yields which were
not significantly lower than the untreated check due to increases in the
alfalfa component of the forage. This was brought about by reduced
weed competition with the alfalfa. In some cases, first cutting forage

yields were significantly reduced due to removal of the weed component,

145

but season total forage yields were not significantly different due to
the increase alfalfa growth.

Alfalfa yield increases were observed at all three sites, but
were observed most often at site three. Site one was a sparse stand of
alfalfa which was unable to compete for the additional water and nutrients
made available by the weed control measures. Site two was an excellent
stand in which the weed pressure present was not a significant yield
reducing factor, therefore, the removal of these weeds did not result in
significant yield effects. Site three was a good stand of alfalfa with
severe weed pressure. The weeds present at this site were a significant
factor in limiting alfalfa yield. The stand was also dense enough to
respond to the reduced weed pressure. Therefore, of the three sites,
treatments at site three resulted in the greatest number of alfalfa
yield increases. Alfalfa yield increases were observed in both 1981
and 1982, however, no treatments applied in 1980/81 resulted in alfalfa
yield increases in 1982 due to the poor weed control provided by these
treatments in 1982.

Of the three parameters chosen to investigate forage quality
protein content was the one most affected. In vitro digestible dry
matter was not significantly different at any cutting, at any site in
either year. Acid detergent fiber content was affected only at the
first cutting, at site one in 1981 and site three in 1982. Forage
protein content was increased by at least one treatment at the first
cutting at all three sites in both years of the study, except the
first cutting at site two in 1982. In most, but not all cases, protein
increases were observed with treatments which increased alfalfa yield.

If weed control programs in established alfalfa are to be

recommended they must represent an economic advantage for the grower

P‘fl

 

 

146

using them. As previously mentioned, of the quality parameters
investigated, protein content was the one most affected. Protein in-
creases were observed in at least one case with all treatments tested.
In many cases these increases in protein content were accompanied by
decreases in total forage yield at the first cutting. When this
occurred, the actual increase in total protein harvested/hectare was
very small. For this reason calculation of the economic benefits of
a treatment should be based on data from treatments which resulted in
an increase in forage protein content without decreasing total forage
yields. These calculations were performed on treatments meeting this
criteria and the results are shown in Table 109. The values in this
table are based on the cost of protein as soybean meal. In no case
did the savings resulting from protein increases exceed the cost of
treatment, indicating these treatments cannot be justified on an
economic basis based on increases in protein content.

Increasing stand longevity has been suggested as a potential
benefit of weed control programs in established alfalfa. Certainly
removing weed competition from an alfalfa stand has this potential,
however based upon the results of this study, in order to maintain
adequate weed control, annual herbicide applications are necessary.
If this is the case, the cost of such a program becomes prohibitive.
A more economically feasible approach to the problem of increasing
stand longevity, or simply maintaining a relatively weed free stand
of alfalfa, seems to be an annual application of simazine (1.46 kg/ha)
in the fall. Although this treatment provides only fair control of
perennial grasses and broadleaf weeds it is sufficiently inexpensive

($10.00/ha) to be used on an annual basis. Protein analysis was not

147

 

 

 

 

 

 

Table 109. Savings vs. cost of some herbicide treatments causing
significant increases in first harvest forage protein
content.

Rate Application Savings
Treatment kg/ha time $/ha Cost
SITE I 1981

Pronamide 1.68 Fall 55.47 95.55

Metribuzin 0.56 Fall 25.61 26.43

Metribuzin 1.12 Spring 43.18 52.85

SITE II 1981
Pronamide 1.68 Fall 34.85 95.55
Metribuzin 1.12 Spring 36.07 52.85
Pronamide 1.68 Fall +
Metribuzin 1.12 Spring 38.18 148.40
SITE III 1981

Pronamide 1.68 Fall +

Metribuzin 1.12 Spring 28.63 148.40
SITE III 1982

Pronamide 1.68 Fall 17.86 95.55

 

148

performed on any forage receiving this treatment, however, metribuzin
(0.56 kg/ha) fall applied provides similar control. This treatment
provided a significant protein increase only at the first cutting at
site one in 1981. Although increases in forage quality may not be
realized from the use of simazine, the suppression in weed growth
provided by annual applications along with high fertility and timely
cutting could prevent weeds from competing too vigorously with the
alfalfa and possibly lengthen the life of the stand. There is a need

for more work to be done in this area.

10.

11.

LITERATURE CITED

Aerts, J.V., D.L. DeBrabander, B.G. Cottyn, and F.X. Buysse. 1977.
Comparison of laboratory methods for predicting the organic matter

digestibility of forages. Animal Feed Science and Technology
2:337-349.

A.0.A.C. 1970. Official methods of analysis (Eleventh ed.).
Association of Official Analytical Chemists. Washington, D.C.

Arnold, W.E. and W.B. O'Neal. 1973. Downy brome control in
established alfalfa. North. Centr. Weed Cont. Conf. Res. Rept.
30:7-8.

Cords, H.P. 1973. Weeds and alfalfa hay quality. Weed Sci.
21:400-401.

Currey, W.L. and R.A. Peters. 1968. Control of yellow rocket and
other broadleaf weeds associated with established alfalfa. Proc.
Northeast Weed Contr. Conf. 22:455-48.

Davis, H.E., R.S. Fawcett, and R.G. Harvey. 1976. The effect of
alfalfa stand density on pronamide control of quackgrass. Proc.
North Centr. Weed Contr. Conf. 30:28.

Duke, W.B. 1970. Effects of RH-315 on quackgrass and established
alfalfa. Proc. Northeast. Weed Contr. Conf. 24:220.

and E.S. Spear. 1969. Weed control in establish

 

legumes. Proc. Northeast. Weed Contr. Conf. 23:212-219.
and J.F. Hunt. 1972. The effects of 4-amino-3-

 

methylthio-G-t-butyl-l,2,4-triazin-5(4H) one (Bay-94337) on weeds
in established alfalfa. Proc. Northeast. Weed Sci. Soc. 26:263-267.

Dutt, T.E. 1977. Herbicides for perennial weed control in established
alfalfa and effects of perennial weedsruiforage quality and animal
performance. Thesis for degree of Ph.D., University of Wisconsin,
Madison, WI.

Dutt, T.E., R.G. Harvey, R.S. Fawcett, N.A. Jorgensen, H.J. Larsen,
and D.A. Schlough. 1979. Forage quality and animal performance as
influenced by quackgrass control in alfalfa with pronamide. Weed
Sci. 27:127-132.

149

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

150

Fawcett, R.S., R.G. Harvey, D.A. Schlough, and I.R. Block. 1978.
Quackgrass control in established alfalfa with pronamide. Weed

Sci. 26:193-198.

Forbes, R.M. 1950. Protein as an indicator of pasture forage

digestibility. J. Animal Sci.

9:231-237.

Fortino, J. 1977. Influence of metribuzin on weed control and
production of alfalfa. Proc. North Centr. Weed Sci. Soc. 1976.

31:102.

Glover, J., D.W. Dutchie, and M.H. French. 1957. The apparent
digestibility of crude protein by the ruminant. I. A synthesis
of the results of digestibility trials with herbage and mixed feeds.

J. Agr. Sci. 48:373.

Harvey, R.G. and S.R. Connor.

in alfalfa with RH-315. Proc. North Centr. Weed Contr. Conf. 26:68-69.

Holter, J.A. and J.T. Reid. 1

Ilnicki, R.D. and L.F. Hist.

Proc. Northeast. Weed Contr. Conf.

1971. Selective control of quackgrass

959. Relationship between the con-
centration of crude protein and apparently digestible protein in
forages. J. Anim. Sci. 18:1339-1349.

1969. Weed control in dormant alfalfa.

23:222.

Kapusta, G. 1973. Common chickweed control in established alfalfa.

Weed Sci. 21:119-122.

Kommedahl, T., J.B. Kotheimer, and J.V. Bernardini. 1959. The
effects of quackgrass on germination and seedling development of

certain crop plants. Weeds 7:

1-12.

Kust, C.A. 1968. Herbicides or oat companion crop for alfalfa
establishment and forage yields. Agron.

J. 60:151-154.

Marten, G.C. and R.N. Anderson. 1975. Forage nutritive value and
palatability of 12 common annual weeds.

Moline, W.J. and L.R. Robison.

Crop Sci. 15:821-827.

1971. Effects of herbicides and
seeding rates on the production of alfalfa. Agron. J. 63:614-616.

Pagano, G.P., R.H. Ackerman, E.A. Cunningham and P.M. Grehlinger.
1977. Managing alfalfa production with metribuzin. Proc. Northeast.

Weed Sci. Soc. 31:104.

Pearson, 5.0. and W.F. Meggitt. 1968. Weed control in established
alfalfa with terbacil and simazine. Res.

Contr. Conf. 25:56-57.

Rept. North Cent. Weed

Peters, E.J. 1964. Pre-emergence, pre-planting and post-emergence
herbicides for alfalfa and birdsfoot trefoil. Agron. J. 56:415-419.

Peters, R.A. and R.M. O'Leary.

Northeast. Weed Contr. Conf.

1967. Herbicidal response of white
cockle and other winter weeds associated with alfalfa. Proc.

21:299-302.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

151

Pruss, W.W. 1969. Control of winter annual weeds in established
alfalfa with simazine. Proc. Northeast. Weed Contr. Conf. 23:227-232.

Robison, L.R., C.F. Williams, and W.A. Laws. 1978. Weed control in
established alfalfa. Weed Sci. 26:37-40.

Schmid. A.R. and R. Behrens. 1972. Herbicides vs. oat companion
crops for alfalfa establishment. Agron. J. 64:157-159.

Sheaffer, L.L. and D.L. Wyse. 1982. Common dandelion control in
alfalfa. Weed Sci. 30:216-220.

Slife, F.W., K.P. Bucholtz, and T. Kommedahl. 1960. Weeds of the
North Central States. Univ. Ill. Agric. Exp. Sta. Circ. 718. 262p.

Swan, 0.6. 1972. Effects of herbicides on alfalfa and subsequent
crops. Weed Sci. 20:335-337.

Temme, D.G., R.G. Harvey, R.W. Fawcett, and A.W. Young. 1979. Effects
of annual weed control on alfalfa forage quality. Agron. J. 71:51-54.

Triplett, 6.8., Jr., R.W. Vankeuren, and J.D. Walker. 1977. The
influence of 2,4-D, pronamide, and simazine on dry matter production
of an alfalfa-grass sward. Crop Sci. 17:61-65.

Tilley, J.M.A., and R.A. Terry. 1963. A two-stage technique for the

jg_yjtrg_digestion of forage crops. J. Brit. Grassland Soc. 18:104.

Van Soest, P.J. 1964. Symposium on nutrition and forage and pastures:
New chemical procedures for evaluting forages. Animal Sci. 23:838-845.

1965. Symposium on factors influencing the voluntary

 

intake of heriage by ruminants: Voluntary intake in relation to
chemical composition and digestibitliy. J. Animal Sci. 24:834-843.

1966. Non nutritive residues: A system of analysis

 

for the repTacement of crude fiber. Journal of the Association of
Official Analytical Chemists. 49:546-551.

1967. Development of a comprehensive system of feed

 

analysis and its application to forages. J. Animal Sci. 26:119-128.
1963. The use of detergents in the analysis of

 

fibrous feeds.. II. A rapid method for the determination of fiber
and lignin. J. Assoc. Off. Anal. Chem. 46:829-835.

and J.B. Robertson. 1980. Systems of analysis for

 

evaluating fibrous feeds. Proceedings: Standardization of analytical
methodology for feeds. Series: International Development Research
Centre. 49-59.

and . 1977. What is fibre and fibre in

 

 

food. Nutr. Rev. 35:12-22.

44.

45.

46.

152

and R.H. Wine. 1967. Use of detergents in the

 

analysis of fibrous feeds. II. Determination of plant cell wall
constituents. J. Assoc. Off. Anal. Chem. 50:50-55.

Viste, K.L. and J.M. Sanborn. 1970. Control of quackgrass in alfalfa
by RH-315. Proc. Northeast. Weed Contr. Conf. 24:227-231.

Waddington, J. 1980. Control of dandelion and sowthistle in alfalfa.
Weed Sci. 28:164-167.

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