LIPRARY

Michigan 3; ‘56
University

This is to certify that the

thesis entitled
HERBICIDAL ACTIVITY AND EFFICACY ON
BLACK NIGHTSHADB (SOLANUM s22.)
IN NAVY BEANS (PHASEOLUS VULGARIS L.)

 

presented by

John Wesley Vandeventer

has been accepted towards fulfillment
of the requirements for

Ph.D. degree in Crop 8. Soil Sciences

 

 

 

Major professor ) E ifi

Date 8/11/78

 

0-7639

HERBICIDAL ACTIVITY AND EFFICACY 0N
BLACK NIGHTSHADE (SOLANUM EEK)

IN NAVY BEANS (PHASEOLUS VULGARIS L.)

 

BY

John Wesley Vandeventer

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Crop and Soil Sciences

1978

ABSTRACT

HERBICIDAL ACTIVITY AND EFFICACY 0N
BLACK NIGHTSHADE (SOLANUM £22 )

IN NAVY BEANS (PHASEOLUS VULGARIS L.)

 

BY

John Wesley Vandeventer

Field studies at three locations were utilized to determine the
effects of selected preplant incorporated herbicide treatments on black

nightshade (Solanum.§p,), navy bean (Phaseolus vulgaris L.), and herbi-

 

cide persistence measured by soil residue analysis and activity on
wheat (Triticum aesitivum L.). As temperature at application increased,
the herbicides were more efficacious on black nightshade, similarly as
organic matter level decreased the same was true. No major differences
due to herbicide usage were seen on navy bean yield or in wheat stand
and yield the following season. No differences were seen in persistence
between ethalfluralin (Nfethyl-N;(2-methyl-2-propenyl)-2,6-dinitro-4-
(trifluoromethyl)benzenamine) and trifluralin (a,a,a-trifluoro-2,6-
dinitro-N,Nfdipropyl-pftoluidine) in the soil fer a period of 470 days.
Black nightshade is an extremely variable species and when plants
grown from two seed sources were compared on a morphological and physio-
logical basis vast response differences were observed. Plants grown

from seed obtained in Michigan (MI) had a yellow anther column in the

John Wesley Vandeventer

flower and toothed proximal portion on the mature leaf while those plants
grown from a California (CA) seed source had a dark brown anther column
in the flower and an entire leaf margin. The plants from the CA seed
source were more vigorous over a 15 to 30 C temperature range. Alachlor
(2-chloro-2',6'-diethy15Nf(methoxymethyl)acetanilide) was the most
efficacious on black nightshade and better black nightshade control re-
sulted from ethalfluralin than trifluralin. These differences in black
nightshade control among substituted dinitroaniline herbicides and be-
tween seed sources were not explained by differential 14C absorption or
distribution. Herbicide metabolism studies involving 14C indicated that
differences may be due to the more rapid metabolism of 14C-ethalfluralin
than 14C-trifluralin. Metabolism was more rapid in the plants grown
from the CA seed source than MI seed source. These observations appear
related to the differences in control in the field and greenhouse and
also account for the herbicidal activity levels observed in plants from

the MI and CA seed sources.

To the beautiful woman that stands with me always, Nancy Ann.

ii

ACKNOWLEDGMENTS

The author wishes to express his sincere appreciation to Dr. William
F. Meggitt fer making this portion of my life enjoyable and rewarding
in a personal and educational way. To Dr. Donald Penner special grati-
tude for watching with a guiding manner throughout the laboratory and
thesis preparation. I would like to acknowledge the assistance rendered
by Dr. Charles Cress, Dr. Mathew Zabik, Dr. Alvin Smucker for their
technical support and thesis critic. To Mr. Robert Bond and Ronald Sterns,
thank you for your training and help with all the field-work. Lastly,
without the support and constant encouragement of my dear wife, Nancy Ann,

this thesis would have been much delayed in completion.

iii

TABLE OF CONTENTS

Page
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . vii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

CHAPTER 1: EFFICACY ON BLACK NIGHTSHADE (SOLANUM AMERICANUM MILL.)
AND ACTIVITY OF PREPLANT INCORPORATED HERBICIDES FOR

 

 

WEED CONTROL IN NAVY BEANS (PHASEOLUS VULGARIS L.) . 3
Abstract . . . . . . . . . . . . . . . . . . 3
Introduction . . . . . . . . . . . . . . . . . . 4
Materials and Methods . . . . . 6
Results and Discussion . . . . . . . . 8
Literature Cited . . . . . . . . . . . . . . . . . . . . . . . 11

CHAPTER 2: MORPHOLOGICAL AND PHYSIOLOGICAL VARIABILITY IN BLACK
NIGHTSHADE (SOLANUM 522.) . . . . . . . . . . . . . . . 21

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 22
Materials and Methods . . . . . . . . . . . . . . . . . . . . . 23
Results and Discussion . . . . . . . . . . . . . . . . . . . . 25
Literature Cited . . . . . . . . . . . . . . . . . . . . . . . 30

CHAPTER 3: ABSORPTION, TRANSLOCATION, AND METABOLISM OF
ETHALFLURALIN AND TRIFLURALIN IN SOLANUM E22: . . . . . 50

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 51
Materials and Methods . . . . . . . . . . . . . . . . . . . . . 53
Results and Discussion . . . . . . . . . . . . . . . . . . . . 55
Literature Cited . . . . . . . . . . . . . . . . . . . . . . . 58
CHAPTER 4: SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . 67

LIST OF REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . 69

iv

LIST OF TABLES

CHAPTER 1

1.

Herbicide treatments applied at locations I, II and
III during 1976 and 1977 . . . . . . . . . . . . .

2. Mean maximum air temperatures for four days prior to
herbicide treatment at locations I and II and correspond-
ing overall black nightshade percent control and percent
organic matter (0.M.) . . . . . . . . . . . . . . . . .

3. Rainfall at locations I and II for June, 1976 and for
locations I, II, and III for June, 1977 . . . . . .

4. Soil mechanical analysis for locations I and II and per-
cent organic matter for locations I, II, and III . .

5. Effect of herbicide treatment on percent black nightshade
control at locations I and 11 during 1976 and 1977 . .

6. Effect of herbicide application on dry bean yield at
location I and location III in 1977 . . . . . . . .

7. The effect of substituted dinitroaniline carry over on
wheat stand density and yield . . . . . . . .

8. Herbicide residue in soil following application of sub-
stituted dinitroaniline herbicides during 470 days at
location I . . . . . . . . . . . . . . . . .

CHAPTER 2

1. Common and chemical names of herbicides used . . .

2. Preplant incorporated, preemergence, and postemergence
herbicides selected for response comparison between two
black nightshade seed sources . . . . . . .

3. Germination response from seeds of two black nightshade
sources to no pretreatment and 24 h soak . . . . . . . .

4. Germination response of seed from two black nightshade

sources to running water bath (11 C) over time

Page

13

14

IS

16

17

18

19

20

32

33

34

3S

Page

Growth response to temperature of black nightshade seed
from two sources with respect to percent germination,
plant height, and dry weight/plant . . . . . . . . . . . . 36

Effect of preplant incorporated herbicide application in
black nightshade plants from two seed sources with respect
to plant number, plant height, and dry weight/plant . . . . 37

Effect of preemergence herbicide application on black
nightshade plants from two seed sources with respect to
plant number, plant height, and dry weight/plant . . . . . 38

Effect of postemergence herbicide application on black
nightshade plants from two seed sources with respect to
plant height and dry weight/plant . . . . . . . . . . . . . 39

CHAPTER 3

1.

Absorption of 14C-ethalfluralin and 14C-trifluralin by
plants from two black nightshade seed sources grown in
nutrient culture after 24 h and 72 h exposure . . . . . . . 60

Distribution of 14C-ethalfluralin and 14C-trifluralin in
plants grown from two black nightshade seed sources in
shoot and root over 24 and 72 h exposure . . . . . . . . . 61

Metabolism of 14C-ethalfluralin and 14C-trifluralin in

shoot and.root components of plants grown from two black
nightshade seed sources after 24 and 72 h exposure . . . . 62

vi

LIST OF FIGURES

Page
CHAPTER 2

1. Morphology of Solanum nigrum L. as depicted in Weeds of
the North Central States (A) and World's Worst Weeds (B). . 41

 

2. Seeds of black nightshade obtained in Michigan (A) and
from California (B). . . . . . . . . . . . . . . . . . . 43

3. Seedlings grown from black nightshade seed collected in
Michigan and obtained from California . . . . . . . . . . . 4S

4. Mature leaves from plants grown from seed collected in
Michigan (A) and obtained from California (B) . . . . . . . 47

5. Flowers on plants grown from black nightshade seed col-
lected in Michigan (A) and obtained from California (B) . . 49

CHAPTER 3

1. Distribution of 14C-ethalfluralin in plants grown from
seeds collected in Michigan (A) and obtained from
California (B). The treated plant specimen is above the
corresponding autoradiograph . . . . . . . . . . . . . . . 64

2. Distribution of 14C-trifluralin in plants grown from
seed collected in Michigan (A) and obtained from
California (B). The treated plant specimen is above the
corresponding autoradiograph . . . . . . . . . . . . . . . 66

vii

INTRODUCTION

Black nightshade (Solanum sp,) has long been a problem for navy bean
farmers. Much has been written about the extreme variability within the
genus. Different descriptions, both written and pictorial, can be found
of Solanum nigrum L. Proper weed control measures are dependent upon
accurate identification of the pest species.

Problems caused by black nightshade are not only competition but
also the discoloration of navy beans at harvest due to the staining juice
present in the black nightshade fruit. The seriousness of this problem
may warrant the use of additional herbicides. Problems arise when weed
control recommendations are based on other than native weed populations.
In some cases even the native populations vary genetically.

Black nightshade control options include the use of preplant incor-
porated herbicides alone or in combination with other preplant incorporated
or preemergence herbicides. The best practice would be to maximize black
nightshade control and crop yield while minimizing herbicide persistence
in the soil and carry over problems for rotational crops. The substituted
dinitroaniline herbicides and alachlor have been the primary choices for
use by the navy bean farmer.

These studies were undertaken to compare and evaluate (1) selected
herbicides for black nightshade efficacy, activity on navy beans and
wheat, soil persistence between ethalfluralin and trifluralin, (2) the
morphological and physiological variability of black nightshade plants

1

2
grown from two seed sources as related to their identification, and (3)
the basis for difference in control with ethalfluralin and trifluralin

applied to plants from two seed sources.

CHAPTER 1

EFFICACY ON BLACK NIGHTSHADE (SOLANUM AMERICANUM MILL.)

 

AND ACTIVITY OF PREPLANT INCORPORATED HERBICIDES

FOR WEED CONTROL IN NAVY BEANS (PHASEOLUS VULGARIS L.)

 

ABSTRACT

Dinitroaniline herbicides and alachlor (2-chloro-2',6'-diethyl-N;

(methoxymethyl)acetanilide) efficacy on black nightshade (Solanum

 

americanum Mill.) native to Michigan and activity on navy beans (Phaseolus

vulgaris L.) and wheat (Triticum aesitivum L.) were examined. Field re-

 

sults indicated that regardless of soil type the most consistent control
of black nightshade was obtained from preplant incorporated alachlor.
Addition of chloramben (3-amino-2,S-dichlorobenzoic acid) or dinoseb
(2-sec-butyl-4-,6-dinitrophenol) as a preplant incorporated tank mix or
preemergence overlay treatment did not increase navy bean yield in all
cases. As the soil organic matter increased, less black nightshade con-
trol was obtained from the addition of chloramben regardless of preplant
incorporated treatment. At one location no difference in navy bean yield
was seen from the addition of chloramben applied preemergence to almost
any preplant incorporated dinitroaniline herbicide except for dinitramine
(N§,Ne-diethyl—a,a,a-trifluoro-3,5-dinitrotoluene—2,4-diamine) where
yields increased more than 40%. Decreased navy bean yields at this same
location resulted from the chloramben addition to alachlor applied

3

4
preplant incorporated. At a lower organic level, location III, highest
navy bean yields resulted from fluchloralin (N-(2-chloroethyl)-2,6-dinitro-
N-propyl-4-(trifluoromethyl)benzenamine) at 1.68 kg/ha and ethalfluralin
(Nfethyl-N;(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)benzena-
mine) at both rates tested (1.12 and 1.68 kg/ha).

No differences were seen in wheat stand or yield resulting from
dinitroaniline carry over at location I. No differences in concentration
of herbicide residue in the soil were found between ethalfluralin and

trifluralin.

INTRODUCTION

Black nightshade (Solanum americanum Mill.) frequently listed as S,
nigrum_L. has long been a serious problem to navy bean (Phaseolus
vulgaris L.) farmers. Until recently options for effective nightshade
weed control in Michigan with preplant incorporate tank mix treatments
consisted of EPTC (Sfethyl dipr0pylthiocarbamate) plus trifluralin (a,a,a-
trifluoro-Z,6-dinitro-N,N;dipr0pyl-p-toluidine), dinitramine (N?,Nfl-
diethyl-a,a,a-trifluoro-3,5-dinitrotoluene-2,4-diamine), or profluralin
(Nrcyclopropylmethyl)-a,a,a-trifluoro-2,6-dinitro-prropyl-p;toluidine)
plus chloramben (3-amino-2,S,-dichlorobenzoic acid) (7). Preplant in-
corporated plus preemergence herbicide treatments consisted of EPTC or a
substituted dinitroaniline herbicide followed by chloramben or dinoseb
(2-sec-butyl-4-,6-dinitrophenol). The weed control with preplant incor-
porated tank mix treatments may be more than from the same preplant in-
corporated plus preemergence treatments under dry conditions. If rainfall,

is received within a short time (4 to 7 days) following application,

S
greater weed control is obtained from the preplant incorporated plus pre-
emergence treatments.

Volatility is an important factor affecting substituted dinitro-
aniline herbicide biological activity. Conditions conducive to volatili-
zation include high soil moisture and high temperature (1). As the soil
moisture increased, trifluralin vaporization increased (15). The vapor
from most of the substituted dinitroanilines is herbicidally active and
diffusion is the greatest under dry soil conditions (1). Soil organic
matter has also been mentioned as an important factor in reducing sub-
stituted dinitroaniline herbicide activity (3,4,8). Variation in soil
persistence from substituted dinitroaniline herbicides has been reported
(11,13,16). The persistence of substituted dinitroaniline herbicides
depends on climatic and edaphic factors that affect their rate of dis—
appearance (12). Results from Saskatchewan indicate that trifluralin
applied at the l to 2 kg/ha rate persisted after one growing season and
declined during the first months of the second season to very low levels
after 2 months.

Ethalfluralin (N;ethyl-Nf(Z-methyl-Z-propenyl)-2,6-dinitro-4-
(trifluoromethyl)benzenamine) is considered to be less persistent in the
soil and offers greater black nightshade control than trifluralin (6,14).
The combination of alachlor (Z—chloro—Z',6'-diethyl-N-methoxymethyl)
acetanilide) plus chloramben (preplant incorporated has similar charac-
teristics.

The objectives of this study were to evaluate: 1) substituted
dinitroaniline herbicide and alachlor efficacy on black nightshade; 2)
effect on navy bean yield from preplant incorporated herbicide treatments

alone and in combination with chloramben and dinoseb applied in a preplant

6
incorporated tank mix or as a preemergence overlay; 3) effect of substi-
tuted dinitroaniline herbicide persistence on wheat stand and yield; and

4) ethalfluralin and trifluralin degradation over time.

MATERIALS AND METHODS

A two year efficacy and persistence study was initiated in June,
1976 in Sanilac Co., MI (location I). Herbicides given in Table 1 were
applied to a sandy clay loam. Treatments were applied in a randomized
complete block design with three replications. Plot size was 3 m by
15.25 m.

All treatments were applied with a tractor mounted sprayer at the
rate of 215 l/ha and 2.1 kg/cmz. All substituted dinitroaniline herbi-
cides were incorporated to a uniform 7.5 cm depth with a spring-tooth
harrow two times at right angles.

Preemergence overlay was applied after planting with "Seafarer"
navy beans on June 21. Identical treatments were applied on June 12 at
Huron Co. (location 11). These plots (location II) were only used for
black nightshade efficacy. In 1977, repeat studies were put out in both
locations I and II on June 12 and 17, respectively. In June 1977,
studies were initiated to evaluate the effectiveness of these same sub-
stituted dinitroaniline herbicides and alachlor at various rates both
alone and in combination with chloramben (locations I and II) and dinoseb
(location III, Gratiot Co., MI) in an applied preplant incorporated tank
mix and as preemergence overlays.

At location I soil samples were taken from each ethalfluralin and

trifluralin plot on seven dates, June 21, July 20, August 22, September

7
30, 1976 and the following April 28, August 5, and October 7, 1977. All
samples were taken with a 19 mm sampling tube to a depth of 15 cm and
consisted of 20 subsamples. After each date, samples were shipped to
Lilly Research Laboratories, Greenfield, IN for analysis using Eli Lilly
and Company Agricultural and Analytical Chemistry Procedure No. 5801616
for trifluralin and Procedure No. 5801633 for ethalfluralin (2,5).

After navy bean harvest at location I, "Tecumseh" wheat (Triticum
aesitivum L.) was planted on October 3 as a rotational bioassay crop.

The following spring wheat density measurements (plants/m2) were taken
and on July 12, 1977 the wheat was harvested with a small plot combine
for yield data.

A split-plot design with four replications was utilized at location
III to study the substituted dinitroaniline herbicides and alachlor
(Table 1) alone and in preplant incorporated tank mix and preemergence
combinations with chlorambem and dinoseb. Treatments were applied on
June 14 and 15 and "seafarer" navy beans were planted on June 15, 1977.
This location was originally thought to have a uniformly dense black
nightshade population. Weed control ratings were made at 40 days, how-
ever, the nightshade population was so variable, it was not included in
the ratings. Navy bean yields were taken at harvest.

Temperature data for the 4 days prior to treatments as an indication
of soil temperature is included in Table 2 for locations I and II. Rain-
fall data is shown in Table 3 for locations I and II for June, 1976 and
locations I, II and III for June 1977 (9.10).

All yield and stand data are expressed as percent of untreated con-
trol. Soil residues are reported in ug/g. Thirty or 40-day weed control

ratings were made on a 0 = no control, 10 = complete control scale and

8
are expressed as percent control. Soil mechanical analysis for locations
I and II and percent organic matter for locations I, II and 111 may be

found in Table 4.

RESULTS AND DISCUSSION

No differences in black nightshade control between locations I and
II was evident in 1976. The most efficacious treatments in 1976 were
trifluralin at 1.4 kg/ha, dinitramine at 0.56 kg/ha, ethalfluralin at
1.68 kg/ha, and pendimethalin at 1.4 kg/ha (Table 5). The temperatures
for the preceeding 4 days prior to treatment averaged 7 C higher at
location 11 than I, the organic matter (0.M.) was also different, loca-
tion I = 9.46% and location II = 6.71%. The effects of temperature and
organic matter may have cancelled each other; location I - lower tempera-
tures and a higher 0.M., whereas location II - higher temperatures and a
lower 0.M. (Table 2).

In 1977 the temperatures prior to treatment were 3 C higher for
location II. The rainfall received within 7 days of treatment was 0.05
cm for location I and 1.1 cm for location 11. The increased rainfall
could have provided the stimulus fer germination along with the warm
temperatures to provide for active growth of weed seedlings in the treated
soil zone giving a significant location by treatment interaction. Better
weed control (Table 5) was seen from four of eleven treatments. The
combination treatments in which chloramben preemergence increased black
nightshade control were trifluralin at both rates (0.86 and 1.4 kg/ha),
profluralin at 1.12 kg/ha, and fluchloralin at 1.68 kg/ha (Table 5).

This increased weed control was probably due to the chloramben because

9
these three herbicides normally do not control black nightshade.
Chloramben application at location I did not increase the level of black
nightshade whereas at location 11 better black nightshade control was
seen from herbicides in combination with chloramben. This difference
in activity may be due to the level of organic matter in these two soils.
As the percent organic matter increased the amount bound or unavailable
fer plant uptake was decreased.

The combination study at location III showed no navy bean yield
differences between any addition to the preplant incorporated treatments,
chloramben as preplant incorporated tank mix or preemergence, or dinoseb
at preplant incorporated tank mix or preemergence. The treatments re-
sulting in the highest navy bean yields were ethalfluralin (1.68 and 1.12
kg/ha) and fluchloralin (1.68 kg/ha) (Table 6).

In 1976 there were no significant navy bean yield differences be-
tween treatments. During 1977 significant differences in yields due to
chloramben addition were seen in three cases (Table 6). Navy bean yield
after treatment with dinitramine compared to dinitramine plus chloramben
was increased by 46%. Adding chloramben to alachlor decreased yields in
both the low and high alachlor rates by at least 45%. No significant
yield differences were seen from the remaining substituted dinitroaniline
herbicide plus chloramben treatments.

Soil persistence of the substituted dinitroaniline herbicide treat-
ments applied in 1976 at location I was measured with wheat, a likely
rotational crop. There was no significant stand or yield effect seen
from any substituted dinitroaniline herbicide treatment on wheat stand
or wheat yield both reported as percent untreated control (Table 7).

Soil persistence over 1 1/2 years previous was determined at

10
location 1 for ethalfluralin and trifluralin. The first sampling date
was immediately following application. The second through fourth dates
followed at approximately 30 day intervals. There were no significant
differences between persistence at the first two dates or the second
through fourth dates (Table 8). Therefbre, presuming extractable herbi-
g cide can be related to potential phytotoxicity, no decreased activity
was seen in the 30 day through the 90 day samplings. A significant de-
crease in herbicide persistence was seen over the first 60 day period.
Samples collected the following spring (310-470 days after application)
were not significantly different. However, lower residue levels were ob-
served one year after application.

During the first 60 days the most dramatic decrease in soil persis-
tence is usually seen. Initial losses were observed to be greater than
subsequent losses. The most dramatic losses occurred during the over—
winter period and in the early spring when excess soil moisture favored
volatilization.

Ethalfluralin residues at both tested rates (1.12 and 1.68 kg/ha)
were the same as that for trifluralin at the 0.84 kg/ha rate over the
470 day period. Trifluralin at the 1.4 kg/ha degraded over the time
period similarly to ethalfluralin at the 1.68 kg/ha rate. Ethalfluralin
was not found to be less persistent with respect to extractable quanti-
ties over time than trifluralin regardless of rate used. The t 1/2 or
point in time at which one half the amount originally sampled was found

for all the four treatments was the fifth date or the following spring.

10.

11.

12.

13.

11

LITERATURE CITED

Ellis, J.F., and J.A. Norton. 1976. Factors affecting the bio-
logical activity of dinitroaniline herbicides. Supplement to
Proc. N. Eastern Weed Contr. Conf. 26:128.

Frank, R. 1976. Determination of ethalfluralin in agricultural
crops and soils. Procedure No. 5801633. Agricultural Analytical
Chemistry, Eli Lilly and Company. Greenfield Laboratories,
Greenfield, IN.

Gingerich, L.L. and R.L. Zimdahl. 1976. Soil persistence of iso-
propalin and oryzalin. Weed Sci. 24:431-433.

Hollist, R.L. and C.L. Foy. 1971. Trifluralin interactions with
soil constituents. Weed Sci. 19:11-16.

Johnson, W.S. 1972. Determination of trifluralin in agricultural
crops and soil. Procedure No. 5801616. Agricultural Analytical
Chemistry, Eli Lilly and Company. Greenfield Laboratories,
Greenfield, IN.

Koren, E., D. Dahan, and M. Marmelstein. 1976. Ethalfluralin -
a new residual herbicide in cotton. Phytoparasitica 4:2:149.

Meggitt, W.F. 1976. Weed control guide for field crops. Ext.
Bull. E-434, Cooperative Extension Service, Michigan State
University. pp. 26.

Miller, C.H., T.J. Monaco, and T.J. Sheets. 1976. Studies on
nitralin residues in soils. Weed Sci. 24:288-291.

National Oceanic and Atmospheric Administration. 1976. Daily
temperatures, June 1976. Michigan Climatological Data. Environ-
mental Data Service, National Climatic Centre, Asheville, NC
92(6):9.

National Oceanic and Atmospheric Administration. 1977. Daily
temperatures, June 1977. Michigan Climatological Data. Environ-
mental Data Service, National Climatic Centre, Asheville, NC
92(6):0.

Probst, G.W., T. Golab, R.J. Holzer, S.J. Parka, C. Van der Schans,
and J.B. Tepe. 1967. Fate of trifluralin in plants and soils.
J. Agric. Food Chem. 15:592-599.

Rahman, A. and R. Ashford. 1973. Persistence of trifluralin under
field conditions in Saskatchewan. Can. J. Plant Sci. 54:421-423.

Schweizer, E.E. and J.T. Holstein Jr. 1966. Persistence of five
cotton herbicides in four southern soils. Weeds 14:22—26.

14.

15.

16.

12

Skylakakis, G., B. Anastasiadis, J. Buendia, R.M. Bayo, Y. Oran,
and W.R. Waldrep. 1974. EL-l6l a new preplant incorporated herbi-
cide for control of grass and dicotyledonous weeds in cotton.
British Weed Contr. Conf. 2:795-800.

Swann, C.W., and R. Behrens. 1972. Phytotoxicity of trifluralin
vapors from soil. Weed Sci. 20:143-146.-

Wiese, A.F., E.W. Chenault, and E.B. Hudspeth, Jr. 1969. Incor-
poration of preplant herbicides for cotton. Weed Sci. 17:481-483.

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13

 

 

 

 

 

 

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14

 

 

 

 

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HH

 

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.N magma

15

Table 3. Rainfall at locations I and II for June, 1976 and for locations
I, II, and III fer June, 1977.

 

 

 

 

 

 

Year
1976 1977
Location Location
I II I II 111

Day (cm) Day (cm)

1 0.23 1 0.97 0.74 0.58
2 2 0.71 1.14 0.79
3 3 T 0.05

4 4

S 5 0.61 0.89 0.05
6 6 0.79 1.04 0.57
7 7 0.13 1.02 0.66
8 8 0.41

9 T 9 0.46

10 10

11 T 11 .20

12 12 0.33 0.18 0.03
13 13 0.08 T

14 14

15 15

16 0 03 0 79 16

17 17 0.10 0.03
18 18 0 58 0.84 1 02
19 2 16 0.97 19 0.05
20 1 04 20 0 03
21 21 0 08
22 T 22
23 23
24 0.05 24
25 0.79 0.20 25
26 T 26 0.74
27 27
28 28 0.71
29 3.12 . 29 0.10 1.14

 

16

Table 4. Soil mechanical analysis for locations I and II and percent
organic matter for locations I, II and III.a

 

 

 

Organic Mechanical Analysis
Matter Sand Silt Clay Texture

Location (%) (%) (%) (%)

I 9.46 52.4 20.72 26.88 sandy
clay
loam

II 6.71 76.40 6.72 16.88 sandy
loam

III 5.0 -- -- -- sandy
loam

 

aAll soil analyses conducted by the Michigan State University Soil Test
Laboratory, 108 Soil Science Building, East Lansing, MI 48824.

l7

 

 

 

 

 

 

 

 

 

 

 

Table 5. Effect of herbicide treatment on percent black nightshade con-
trol at locations I and II during 1976 and 1977.
Year
19763 1977
Black Location
night- Black nightshade
Rate shade Rate (%C)
Herbicideb (kg/ha) (%C) Herbicide (kg/ha) I II
Trifluralin 0.84 57 ac Trifluralin 0.84 33 ab 78 d-g
1.40 66 abc 1.40 28 a 87 d-g
Profluralin 1.12 62 ab Profluralin 1.12 28 a 81 d-g
Fluchloralin 1.68 62 ab Fluchloralin 1.68 40 abc 80 d-g
Dinitramine 0.56 80 c Dinitramine 0.56 54 a-d 79 d-g
Butralin 1.68 62 ab Butralin 1.68 63 b-g 58 a-e
Ethalfluralin 1.12 63 ab Ethalfluralin 1.12 60 a-f 72 c-g
1.68 75 bc 1.68 77 d-g 68 c-g
Pendimethalin 1.40 78 bc Pendimethalin 1.40 70 c-g 95 fg
Alachlor 2.24 96 fg 93 efg
2.80 82 d-g 98 g
Combinations
Black nightshade
w/o w/
chloramben chloramben
Location (%)
I 52 a 63 ab
11 66 b 96 c
:Black nightshade control values are means of both locations I and II.

applied preemergence.
eans within years and section followed by the same letter are not sig-
nificantly different at the 5% level by Duncan's multiple range test.

All herbicide treatments are in combination with chloramben (2.24 kg/ha)

18

Table 6. Effect of herbicide application on dry bean yield at location
I and location 111 in 1977.

 

 

 

 

I
yieldb 1113
Rate w/o chloramben w/ chloramben yieldc
Herbicide (kg/ha) (%C)d (%C)d
Trifluralin 0.84 174 b-g 186 c-h 152 bc
1.40 174 b-g 163 a-d 151 bc
Profluralin 1.12 185 c-h 161 abc 137 ab
Fluchloralin 1.68 174 b-g 180 b-g 157 bed
Dinitramine 0.56 171 b-f 218 h 140 ab
Butralin 1.12 145 ab 160 abc 142 ab
Ethalfluralin 1.12 170 b-c 202 e—h 165 cd
1.68 176 b-g 208 gh 172 d
Pendimethalin 1.40 188 c-h 162 abc 151 be
Alachlor 2.24 198 d-h 134 a 147 bc
2.80 206 fgh 161 abc 147 bc

 

aYield means are the average for treatments alone and in combination with
chloramben 2.24 kg/ha, preplant incorporated tank mix and preemergence,
and dinoseb 5.04 kg/ha, preplant incorporated tank mix and preemergence.
bNo treatment dry bean yield at location I in 1977 was 788 kg/ha (7.03
cwt/A).
cNo treatment dry bean yield at location 111 in 1977 was 788 kg/ha
(7.03 cwt/A).
eans within locations followed by the same letter are not significantly
different at the 5% level by Duncan's multiple range test.

19

Table 7. The effect of substituted dinitroaniline carry over on wheat
stand density and yield (both expressed as % untreated control).

 

 

rate Wheat Wheat
Herbicide (kg/ha) stand density yield
Trifluralin 0.84 109 86

1.40 94 88
Profluralin 1.12 102 98
Fluchloralin 1.68 70 89
Dinitramine 0.56 96 94
Butralin 1.68 99 92
Ethafluralin 1.12 96 104

1.68 89 71

Pendimethalin 1.40 98 99

 

20

Table 8. Herbicide residue in soil following application of substituted
dinitroaniline herbicides during 470 days at location I.

 

 

Sampling Residue levelac Application Residue levelbc
date (us/g) Herbicide (kg/ha) (us/g)

6/21/76 0.44 c trifluralin 0.86 0.22 a
7/20/76 0.33 be 1.40 0.31 b
8/22/76 0.29 b ethafluralin 1.12 0.19 a
9/30/76 0.31 b 1.68 0.26 ab
4/28/77 0.14 a

8/5/77 0.13 a

10/7/77 0.07 a

 

aResidue levels are the mean of four treatments and both herbicides.

bResidue levels are the means of seven sampling dates.

cMeans within columns followed by the same letter are not significantly
different at the 5% level by Duncan's multiple range test.

CHAPTER 2
MORPHOLOGICAL AND PHYSIOLOGICAL VARIABILITY

IN BLACK NIGHTSHADE (SOLANUM E223)

ABSTRACT

Plants from two black nightshade seed sources were compared for dif-
ferences in morphology at seedling, mature plant, and flowering and physio-
logical response to pregermination seed treatment, growth responses to
temperature, and herbicide response.

Differences in morphology of these two Solanum spp, were evident
from seedling through maturity. The plants grown from the MI seed source
had a deep purple abaxial leaf surface at 3 to 4 leaf stage and a yellow
anther column and toothed proximal half in the mature leaf whereas the
plants grown from the CA seed source had no unusual abaxial coloration
or toothed proximal margin and had a dark brown anther column. From this
point differing responses to treatment between seed source were evident.
Throughout the temperature studies, plants from the CA seed source were
more vigorous. 0f the herbicides evaluated, very few controlled black
nightshade. Differences in response to herbicides were seen between
plants grown from the two seed sources following preplant incorporated,
preemergent and postemergent herbicide application. The greatest differ-
ences in plant growth were with chloramben (3-amino-2,S-dichlorobenzoic
acid) applied preplant incorporated at 1.68 kg/ha and ethalfluralin

21

22
(Nfethyl-Nf(2-methy1-2-propeny1)-2,6-dinitro-4-(trifluoromethyl)benzen-
amine) applied preemergence at 1.12 kg/ha where plants from the MI seed
source were almost always at least 5 times more susceptible than plants
from the CA seed source. Plants from two black nightshade seed sources

have been described as Solanum nigrum L. However, differences in morpho-

 

logy and physiology indicated genetic differences. The plants from MI

have been identified as Solanum americanum Mill. and those from CA as

 

Solanum scabrum Mill. This correct identification could resolve con-

 

flicting reports among researchers regarding chemical control measures.

INTRODUCTION

The Solanum S22, is recognized as having great variability causing
taxonomic difficulties (13). The most widespread species group in the
complex is Solanum EEEEEE.L- S, nigrgm L. is reported as a weed in 61
countries and in 37 crops. The common name associated with the S, pigggm_
L. in the United States is black nightshade (9). Black nightshade, often
reported as S, pigggm_L., has been reported to be a serious pest in row

crops including sugar beets (Beta vulgaris L.) (14), soybeans (Glycine

 

max L. Merr.) (2,10), lima beans (Phaseolus limensis L.) (3), corn (Zea

 

 

EEXE.L°) (9,18) and dry beans (Phaseolus vgigaris L.) (6,7,16).
Temperatures between 25 and 30 C (4) and more specifically 30 C
are Optimum for germination and for seedling growth (5). Germination was
significantly affected by planting depth. Depths below 0.25 cm signifi-
cantly reduced the percent germination regardless of soil type (5).
In an earlier study (17), black nightshade seed was obtained from

a Califbrnia (CA) based seed supplier in the spring of 1976 and seed was

23
obtained from Michigan fields (MI). After growing plants under identical
greenhouse conditions, morphology of plants from the MI seed sources re-

sembled the S, nigrum L. seen in Weeds of the North Central States (15)

 

and Nebraska Weeds (11), while the morphology of the CA seed source

resembed S, nigrum L. from World's Worst Weeds (9) (Figure l).

 

The objectives of this study were to compare morphology of these
two black nightshade seed sources regarding their seed, seedling, and
mature stages and to study their physiology with regard to germination
and its inhibition, growth response to temperature, and responses to pre-

plant incorporated, preemergence and postemergence herbicide treatments.

MATERIALS AND METHODS

Fruits from native (MI) black nightshade (Solanum sp.) were collected
in Sanilac Co., MI from the soil surface after the fruits had fallen.
Fruits were air dried at 22 C and seeds separated from the dried fleshy
portion and stored under refrigeration (4 C) until 48 h prior to use.
Pre-cleaned black nightshade (Solunum sp.) seed was obtained from a
California (CA) based seed supplier (Valley Seed Co., Fresno) and stored
under identical conditions until 48 h prior to use.

For the morphology study, seeds from both the MI source and CA
source were compared at 30X magnification. Seeds from both sources were
planted at 0.5 cm depth and seedlings allowed to grow in the greenhouse
with natural light and supplemental fluorescent lighting 16 h/day at
25 :_3 C. At seedling, mature plant, and flowering stages morphological
comparisons were made with regard to size, coloration (stem and leaf

adaxial and abaxial surfaces) leaf veination and shape, and floral

24
characteristics.

For the physiology study, germination was examined with seeds from
both MI and CA sources from plants grown under identical conditions, then
subjected to: 1) no pre-treatment; 2) soaked in l, 10, 25, 50, and 100
m1 of distilled water for 24 h; and 3) washed in running tap water (11 C)
for 1, 2.5, 5, 7.5, 12, 48, and 108 h. After the above mentioned, seeds
were placed on wet filter paper in plastic petri dishes, sealed with
parafilm and incubated in a lighted growth chamber (16 h/day) at 25 C for
14 days and germination percentage determined.

To determine whether plants from the two seed sources responded dif-
ferently to temperature, growth chamber studies were run at 15, 20, 25
and 30 C and percent emergence and seedling growth were evaluated.
Florescent/incandescent supplemental lighting (16 h/day) was used and
surface irrigation was provided as necessary.

To determine whether the plants from the two seed sources responded
similarly to herbicides, the herbicides listed in Table 1 were selected
on their potential field use at use rates for preplant, preemergence and
postemergence application to navy beans or use in the navy bean crop
rotation (Table 2).

Preplant incorporated and preemergence herbicide treatments were
applied to a greenhouse soil mix (3 soilzl sand) with approximately 7.5%
organic matter. All herbicides were applied with a link belt sprayer at
2.1 kg/cm2 in 280 l/ha. All preplant incorporated treatments were in-
corporated in a mechanical rolling mixer. Fifteen seeds were planted per
946 ml waxed paper cup at 0.5 cm depth.

Postemergence treatments were applied to four plants/cup at the one

true leaf stage and harvested 3 weeks later.

25
A11 plants were grown in the greenhouse with surface irrigation,
supplemental lighting (16 h/day), and at 25 C. Treatments were randomized
in a complete block design with four replications. All data reported are

the means of two experiments.
RESULTS AND DISCUSSION

As seen in Figure 2, the seeds from MI are approximately 1.5 to 1.7
mm by 0.9 to 1.0 mm while the seeds from CA are much larger being approxi-
mately 2.5 to 2.8 mm by 1.5 mm. When viewed at a magnification of 30X
seed from both sources had a rough appearing seed coat that was coarsely
grained and pitted. The seed from the MI source had a yellow-golden tan
coloration while the seed from the CA source had a charcoal-grey black
coloration. Seed from both sources had the same exterior shape and form.

At the cotyledon stage of development no apparent differences in
plant morphology were evident. When the seedlings had two to four leaves,
differences in the coloration of the abaxial surface of the leaves were
evident (Figure 3). Plants from the MI source had prominent veination
and a deep purple color on the abaxial side while plants from the CA seed
retained a green color on the abaxial side. The stems of the plants from
the MI source also had similar purple coloration as the abaxial leaf
surface. Seedlings from the CA source appeared more vigorous than those
from the MI source.

At maturity, the leaves from plants from the two sources no longer
exhibited the difference in abaxial coloration but did have differing
leaf margins (Figure 4). Plants from the MI source had an ovate shape

with a distinct serrated margin on the proximal half. Plants from the

26
CA source had an ovate leaf with uniformly entire margin.

Flowers from plants from the MI seed source and CA seed source were
clustered in groups of two to five and three to seven, respectively, and
had a calyz of five united sepals; white petals were on those from the
CA source or white tinged with purple from the MI seed source. The
anthers were united in plants from both sources. Anthers from the MI
seed source formed a yellow column while those from the CA seed source
formed a dark brown column (Figure 5).

The description for the plants grown from the MI seed source resembled

that given for S, nigrum L. in both Weeds of the North Central States (15)

 

and The World's Worst Weeds (9). The description for the plants from the
CA seed source stated above with the exception of the dark brown united

anthers also resembled S, nigrum L. in The World's Worst Weeds. The

 

plants grown from the MI seed source, however, did resemble the descrip-

tion (1) for Solanum americanum Mill. The morphological differences in-

 

dicated that we may possibly be examining other species entirely.

The effect of the pre-germination seed treatment also showed differ-,
ences with regard to seed source (Table 3). No pre-treatment at all re-
sulted in no significant difference between sources and a low germination
percentage from both sources (MI 5%, CA 18%). Although there were no
differences due to the soaking volumes over 24 h, the germination response
to 24 h soaking was significant for the CA source. The percent germina-
tion of the MI seed was significantly less, when soaked for 24 h, indi-
cating genetic differences between sources.

The germination study using a running tap water bath over time re-
sulted in a significant seed source by time interaction. We expected

an increase in the percent germination with time considering that a

27
germination inhibitor may have caused low germination. However, this was
not the case as the longer the seed from the two sources was in the 11 C
bath, the lower the percent germination (Table 4). From 1 h to 108 h
after soaking the germination percentage of seed from the MI source de-
creased from 76 to 52%, whereas the germination percentage of seed from
the CA source decreased from 68 to 22% (Table 4). Germination may have
been reduced with time by the low temperature and oxygen content of the
tap water.

The response of plants from the two sources to temperature as measured
by percent germination and plant height showed a significant temperature
by source interaction fOr germination. Plant height varied with seed
source (Table 5). Seeds from the MI source failed to germinate at 15 C
compared to the seed from the CA source with 49% germination. Seed from
the CA source germinated especially well over the range of 15 to 30 C.
Plants from both sources showed increased plant height with increased
temperature. No differences were observed between or among temperature
or source with respect to dry weight/plant (Table 5).

Plants from the two sources also responded differently to the selected
preplant incorporated herbicide treatments (Table 6). The most pronounced
difference was observed with respect to plant number, plant height and
dry weight/plant (all as percent of control) fOllowing treatment with
chloramben at 1.68 and 2.24 kg/ha. Plants from the MI seed source were
much more susceptible to chloramben. Ethalfluralin showed more activity
on plants from both sources than trifluralin.

Preemergence application of chloramben alone or in combination with
alachlor was equally effective on plants from the two sources (Table 7).

Plants from the CA source appeared more tolerant to ethalfluralin and

28
metolachlor than plants from the MI source. This is not significant for
ethalfluralin as this herbicide is usually preplant incorporated. At
both rates of bentazon tested, the postemergence application appeared
less effective on the plants from the MI source with regard to plant
height and dry weight/plant (Table 8).

Responses observed in plants grown from the MI seed source are
generally consistent with those observed in Michigan State University
field trials. Preplant incorporated herbicides applied to seeds planted
from both sources were generally ineffective with the exception of ala-
chlor and alachlor plus chloramben at all rates tested. In addition to
the aforementioned herbicide treatments, ethalfluralin and dinitramine
have generally resulted in black nightshade control in Michigan. A possi-
ble reason for this may be that consistent watering in the greenhouse com-
pared to infrequent natural rainfall provided a soil atmosphere conducive
to herbicide loss resulting in reduced black nightshade efficacy, except
when ethalfluralin was applied as a preemergence treatment. Under field
conditions, ethalfluralin applied as a preemergence herbicide has not
resulted in good black nightshade control at these tested rates. Reasons
fer this may be reduced field efficacy caused by chemical volatility and
photodecomposition caused by ultra-violet light.

Postemergence herbicide treatments applied to plants grown from both
the MI and CA seed sources were generally ineffective. Similar results
for native MI black nightshade have been reported in field studies.

Both the morphological and physiological studies showed marked
differences between plants from the two seed sources. If both were S,
nigggm as classified (15,9), then conflusion in their control by various

herbicides may be explained. Confusion could be avoided if these plants

29
were reclassified. After careful systematic examination Schilling (12)
has suggested that neither plant from these two sources be classified

as S, pigrgm_and that the plants from the MI source were S, americanum

 

Mill. and plants from the CA source were S, scabrum Mill. Future use of

this classification system should help avoid confusion.

10.

11.

12.

13.

14.

30

LITERATURE CITED

Alex, J.P. and C.M. Switzer. Ontario Weeds. Ministry of Agric.
and Food Pub. No. 505. p. 200.

 

Anderson, R.N. 1968. Soybeans. Research Report, N. Centr. Weed
Contr. Conf. 25:102-106.

Binning, L.K. 1970. Preemergence herbicide for lima bean weed
control. Research Report, N. Centr. Weed Contr. Conf. 27:70

Binning, L.K. 1971. Black nightshade (Solanum nigrum L.), a
problem weed and its control. Proc. N. Centr. Weed Contr. Conf.
26:128.

Burgert, R.L. and O.C. Burnside. 1972. Optimum temperature for
germination and seedling development of black nightshade. Research
Report, N. Centr. Weed Contr. Conf. 29:56-57.

Doersch, R., R.G. Harvey, L.K. Binning and T.F. Armstrong. 1974.
Response of edible beans to alachlor. Proc. N. Centr. Weed Contr.
Conf. 29:78.

Fenster, C.R. and G.A. Wicks. 1974. Weed control in field beans
in Nebraska. Proc. N. Centr. Weed Contr. Conf. 25:76.

Harvey, R.G. 1972. Herbicide performance in corn. Research
Report, N. Centr. Weed Contr. Conf. 29:179-183.

Holm, L.G., D.L. Pluckett, J.V. Pancho, and J.P. Herberger. 1977.
The World's Worst Weeds. The Univ. Press of Hawaii. Honolulu,
Hawaii. p. 609.

Lueschen, W.E. and P.M._Mi11er. 1975. Control of black nightshade
in soybeans. Research Report, N. Centr. Weed Contr. Conf. 36:210-
211.

Nelson, E.W. and O.C. Burnside. 1975. Nebraska Weeds. State of
Nebraska, Dept. of Agric., Weed Div. Lincoln, NB. p. 312.

 

Schilling Jr., E.E. 1978. A systematic study of Solanum nigrum
in North America. Dept. of Biology Ph.D. Thesis, Indiana
University, Bloomington, IN.

Stebbings Jr., C.L. and E.E. Paddock. 1949. The Solanum nigrum
complex in Pacific North America. Mandrono. 10:70-80.

Sullivan, E.E., L.T. Fagala and T.R. O'Hare. 1969. Herbicide
evaluation studies on sugar beets, 1969. Research Report N.
Centr. Weed Contr. Conf. 26:77-79.

15.

16.

17.

18.

31

University of Illinois. 1973. Weeds of the North Central States.
Agric. Exp. Sta. Circ. No. 718, N. Centr. Reg. Pub. No. 36. p. 262.

 

I Vandeventer, J.W., W.F. Meggitt and R.C. Bond. 1976. Preplant

incorporated, preemergence, and postemergence herbicides for weed
control in navy beans. Research Report, N. Centr. Weed Contr. Conf.
32:166.

Vandeventer, J.W., W.F. Meggitt and D. Penner. 1976. Black night-
shade control in navy beans. Proc. N. Centr. Weed Contr. Conf.
31:36. .

Wicks, G.A. 1970. Preplant, preemergence and postemergence herbi-
cides for corn in southwestern Nebraska. Research Report, N. Centr.
Weed Contr. Conf. 27:96-97.

Table 1.

32

Common and chemical names of herbicides used.

 

Common name

Chemical name

 

Alachlor

Bentazon

Chloramben
Desmedipham

Dinitramine

Ethalfluralin

Ethofumesate

Metolachlor

Phenmedipham

Trifluralin

2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide

3-isopropyl-lH-2,1,3-benzothiadiazin-4-(3H)-one 2,2-
dioxide

3-amino-2,S-dichlorobenzoic acid
ethyl m-hydroxycarbanilate carbanilate (ester)

Efliflfl-diethyl-a,a,a-trifluoro-3,5-dinitrotoluene-2,4-
diamine

N-ethyl-N-(Z-methyl-Z-propenyl)-2,6-dinitro-4-
(trifluoromethyl)benzenamine

2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl
methanesulphonate

2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-
methylethyl)acetamide

methyl m-hydroxycarbanilate m-methylcarbanilate

a,a,a-trif1uorO-2,6-dinitrO-N,S-dipropyl-p-toluidine

 

3
3

 

 

 

 

 

em.o + em.o eeeeeeeeeeee we.H + e~.~ eeeaeeeaee em.o + 4N.o eeeseeeeefle
vm.o + wm.o + amnmweoemoe wo.H + mo.H + Hoacomam
wo.~ + vm.m conamuoaao
ew.o .em.o aeeeeeeeeeea e~.~ .me.H seeseeeHeO we.H + we.H + eeseeeae
vw.o .om.o SmnmfieoEmoe em.m .NH.H :HHeHSHmmcuo em.~ .wo.H neanowam
em.m .NH.H Dummoapmozpo om.m .vN.N noagumfiouoa vm.o :fiHmHSHMMHu
~H.~ .om.o cenmpcon v~.~ + mo.~ neanomam vm.~ .NH.H cflHmusamHmzpo
mm:\mxv oewownnom mm:\wxv OCAOAQHo: mm:\mxv oewuflnno:
neveuem flmveuem Amvepem
oocuwuoEOumom mocowwOEOOHm eoumnomuoocfi pcmamoum

 

vogue: :ofimeAHmm<

 

.moonzom emom oemgmpnwflc xoman 03» coozuon
comwnmmaoo omcommon How eouooHom moefi0flnu6: monomhoeoumom new oocomnoEOOHm .eoumnomuoocw uneamoum .N oanmb

34

Table 3. Germination response from seeds of two black nightshade sources
to no pretreatment and 24 h soak.a

 

Seed treatment

 

 

none 24 h soakb
Seed source (% germination)
Michigan 5 a 37 a
California 18 a 62 b

 

aMeans fOllowed by similar letters within columns are not significantly
different at the 5% level by Duncan's multiple range test.
bValues are the means of treatments.

35

Table 4. Germination response of seed from two black nightshade sources
to running water bath (11 C) over time.a

 

Seed source

 

 

Time in water MI CA
bath (h) (% germination)

l 76 d 68 cd
2.5 52 be 81 d
5 60 cd 68 cd
7.5 72 cd 33 ab
12 62 cd 32 ab
48 51 be 38 ab
108 52 be 22 a

 

aMeans fbllowed by similar letters are not significantly different at
the 5% level by Duncan's multiple range test.

36

Table 5. Growth response to temperature of black nightshade seed from
two sources with respect to percent germination, plant height,
and dry weight/plant.a

 

 

 

 

 

Germination Plant height Dry weight/plant
Temperature MI CA MI CA MI CA
(C) (%) (mm) (mg)
15 0 a 49 cd 0 a 15 ab 0 a 12 a
20 10 b 58 d 19 abc 19 abc 7 a 23 a
25 31 be 56 d 18 abc 36 bc 26 a 33 a
30 25 b 47 cd 35 be 38 c 12 a 28 a

 

aMeans followed by similar letter within parameters are not significantly
different at the 5% level by Duncan's multiple range test.

He He>eH am

on» we ucoquMHe Haucm6HMchflm we: one whopuoa

.pmou omcoa oamflpHss m.:oo::a
HmHfiawm xn eoonHom mnouosouom efiguwz memozm

 

 

ee omH e mm e eHH ee em o-e mm ee AN o.~

eee emH e A e oeH am am m-e ooH em mm we.H eeeaeAeHeu
eee meH e moH e mmH e m~H m-e mHH m 04H em.o

eon mmH e com e meH e meH mm wNH o-o mm «4.0 eeHeeeuHeHa

e em e m ea mm e NH Bee em e oH we.H+eN.N eeeaeeeHee

“u e Hm e H one me e e ea an e oH we.H+we.H + HeHHeeH<
e mH e e ee am pm em on em ea em e~.~

e an e H one me e mH one we e NH we.H HeHeeeH<

ee maH ee weH e NmH e meH w-e eoH m-e moH ew.o eHHeHBHHHee
e eH e AH ee em on em m-e eoH w-e moH e~.~

e e4 e me one om e on m-e eHH woe «NH NH.H eHHeesHmeeem

<6 H2 B<o Hz <u Hz Heg\mxv eeHeHeHe:
oonsom oonsom ouuaom ovum

 

uemfimstwfloz Hug

 

pewHee eeeHa

 

Hones: Human

 

m.aHonu:oo we w mo eommoumxov uemHm\pnwfio3 xue cam .unwflo: ueon .Honase ucmHm op uuoamon so“: moonsom
eoom oz» Scum mucmHm oemnmunmfia Home cw cowmeHammm oeflownno: woumuomnoocfl unmamoum mo uuommm .o oHnob

38

.umou omcon onHpHss m.:o6::o

xn Ho>oH wm opp no acoHoHMHe HHHGNOHMHeme no: one mnowuoH HmHHEHm xn eoonHom muouoamuem :Hnqu mqoozo

 

 

 

 

 

w o m o m o m o a o w o wo.H+vN.N :onEmHoHno

m o m o m o m o m o m o w©.H+wo.H + HOH£UMH<

m CH m H Una am am 5 find mH an n VN.N

m Hm m N on mm no u cam HN m m m©.H conENHoch

w mH m m use HN no a oun mm m N VN.N

a ooH m H v Nu m m ow vm an n NH.H :HHmthmHmnum

m Hm m o o 0? m o cum mH m o om.m

w HN m H 0 ov a m o Hv a v VN.N HoHnomHoqu
d w m o no wH m C unm w m o VN.N

w mH m 0 09m ON a 0 0:9 mm m o we.H HoHcomH<
<6 Hz <6 H2 <6 H2 HERO: 833$:

oonsom oonsom oonsom oped
acmHm\uano3 aha quHon ucmHm Hones: pcmHm

 

«.mHonueoo mo « mm commonmxov ueon\uano3 Aye ecu .ugmHo: ueon .Honesc ucon ow woommoa
anz moousom doom oz» achm mucon oemcmpan: MooHn :o :OHHMOHHQQN oeHOHnuo: oocomuosoonm mo uoommm .5 oHnmh

39

Table 8. Effect of postemergence herbicide application on black night-
shade plants from two seed sources with respect to plant height,
and dry weight/plant (expressed as % of control).3

 

Plant height

 

Dry weight/plant

 

 

Rate Source Source
Herbicide (kg/ha) MI CA MI CA
Bentazon 0.56 73 d 38 bc 60 f 22 a-d
1.12 73 d 43 bc 49 ef 24 a-d
Ethofumesate 1.12 58 cd 47 c 28 a-e 29 a-e
2.24 52 cd 47 c 31 b-e 33 cde
Desmedipham 0.56 52 cd 56 cd 32 cde 27 a-d
0.84 45 c 36 be 37 de 16 a-d
Phenmedipham 0.56 53 cd 47 c 29 a-e 11 ab
0.84 42 bc 12 a 18 a-d 8 a
Desmedipham + 0.34+0.34 48 c 42 bc 28 a-e 12 abc
phenmedipham 0.56+0.56 41 be 20 ab 27 a-d 10 ab

 

aMeans within parameters followed by similar letters are not significantly
different at the 5% level by Duncan's multiple range test.

40

Figure l. Morphology of Solanum nigrum L. as depicted in Weeds of the

 

 

North Central States (A) and World's Worst Weeds (B).

 

 

41

 

42

Figure 2. Seeds of black nightshade obtained in Michigan (A) and from
California (B). ‘

43

..
. 1.
t
H IL .
_. , .
v 1*
w
, 1.-
1
I :1

 

 

44

Figure 3. Seedlings grown from black nightshade seed collected in
Michigan and obtained from California.

45

 

46

Figure 4. Mature leaves from plants grown from seed collected in
Michigan (A) and Obtained from California (B).

 

48

Figure 5. Flowers on plants grown from black nightshade seed collected
in Michigan (A) and obtained from California (B).

 

CHAPTER 3
ABSORPTION, TRANSLOCATION, AND METABOLISM

OF ETHAFLURALIN AND TRIFLURALIN IN SOLANUM EBB:

ABSTRACT

Roots of black nightshade (Solanum E23) seedlings treated with
14C-ethalfluralin (N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-
(trifluoromethyl)benzenamine) and 14C-trifluralin (a,a,a-trifluoro-2,6-
dinitro-N,N-dipropyl-p-toluidine) were grown to determine the basis fer
differences in response by plants from two different seed sources.

Plants grown from the California seed source absorbed more 14C-
ethalfluralin and 14C-trifluralin than plants from the Michigan seed
sources although no differences were seen in susceptibility between plants
grown from the seed sources subjected to preplant incorporated herbicide
application in earlier research. During the first 24 h, seedlings from
the California seed source absorbed more 14C-ethafluralin than did plants
treated with 14C-trifluralin. After absorbed of 14C-ethalfluralin and
14C-trifluralin were equal by plants from the Michigan seed source.

More 14C-ethalfluralin than 14C-trifluralin was found in the black
nightshade shoots of both seed sources. The activity of 14C in roots
was similar after treatments with the two herbicides which could indicate
a greater activity of ethalfluralin.

Seventy-two h after treatment with 14C-labelled herbicides, the

50

51
conversion to the water-soluble fraction was greater for 14C-ethalfluralin
than for 14C-trifluralin. In the shoots of both seed sources an average
14C-concentration of nearly 55% occurred in the water-soluble fraction
following 14C-ethalfluralin treatment while an average of only 40% was

in the water-soluble fraction following 14C-trifluralin treatment.
INTRODUCTION

Early studies (4) showed very little absorption and translocation
of trifluralin (a,a,a-trifluoro-Z,6-dinitro-N,N-dipr0pyl-pftoluidine)
incidating that translocation was not sufficient to be of any consequence
(8). Probst ggngl. (12) did not detect trifluralin or any of its degrada-

tion products in the leaves, seeds, or fruits of soybean (Glycine max L.

 

Merr.) and cotton (Gossypium hirsutum L.). However, trifluralin was

 

fOund in the outer layers of root crops such as onion (Allium gp, L.) and

garlic (Allium sativum L.). This suggested that the incorporation of the

 

14C-trifluralin based on the universal distribution of the radioactivity
without definite parent or metabolite identification. Kechersid g£_§l,
(7) observed acropetal and basipetal trifluralin movement in peanut

(Arachis hypogala L.). .14Carbon labelled C-trifluralin was found in all

 

parts of three stages of peanut seedlings (leaves, epicotyl, cotyledons,
hypocotyl, and roots), indicating extensive translocation. Penner (10)
showed that temperature at which plants are grown had a greater effect
than temperature at the time of treatment. He also found 14C-trifluralin
in roots and shoots of corn (§§a_May§_L.) and soybean. Generally, more
14C was found in roots and shoots of corn than soybean. Hawby (5) fOund

barnyardgrass (Echinochloe crus-galli (L.) Beauv.) and sorghum (Sorghum

 

52
bicolor (L.) Moench), the susceptible species, accumulated more 14C-pro-
fluralin (N-(cyclopr0pylmethyl)-a,a,a-trif1uoro-2,6-dinitro-N-propyl-p-
toluidine) and 14C-dinitramine (N4,_N4-diethyl-a,a,a-trif1uoro-3,5-dini-
trololuene-2,4-diamine) in roots and shoots than did resistant species

Palmer amaranth (Amaranthus palmeri S. Wats) and soybean. Little l4C-

 

profluralin translocated to the shoots, whereas much 14C-dinitramine
accumulated in the plant shoots.

Considering the species in which C absorption and translocation
have been found (e.g., cotton and soybean (l4), sorghum (1), sweet potato

(Ipomea butatas L.) (2), red kidney bean (Phaseolus vulgaris L.) (3) and

 

the previously mentioned species) it appears that substituted dinitroani-
line absorption and translocation is herbicide dependent and that more
14C translocation is seen in susceptible than tolerant species.

Recently, researchers (15,16) have fbund that two Solanum ER: gave
different responses to ethalfluralin (N-ethyl-N(2-methyl-2-propenyl)-2,
6-dinitro-4-(trifluoromethyl)benzenamine) and trifluralin. Skylakakis
g£_al, (13) reported that ethalfluralin application resulted in at least
86% control of black nightshade (Solanum nigrum L.). Koren gt_al, (9)
reported ethalfluralin application controlled annual grasses and broad-
leaved weeds in cotton, even trifluralin resistant Solanum £2:

The objectives of this study were to determine whether these previous-
ly observed differences between ethalfluralin and trifluralin could be

explained on the basis of absorption, translocation, or metabolism.

53

MATERIALS AND METHODS

Native black nightshade (seed source 1) fruit was collected from
Sandusky, MI, after falling from the mature plant, allowed to dry, and
cleaned. Seed for the second Solanum E2: was secured from a California
based commercial seed supplier (Valley Seed Co., Fresno). Seed from
both sources was stored at 11 C until 48 h prior to use and then at room
temperature.

Seed from both sources was germinated and grown in #18 Ottawa washed
quartz sand in 50% Hoagland's nutrient solution (6) in growth chambers
with 16 k/day at 25 :_2 C. Light intensity at plant level was 24 to 27
klux provided by a mixture of fluorescent and incadescent lamps. At the
two to four leaf stage, seedlings of both sources were transplanted to
feil wrapped 21 by 70 mm glass shell vials with sponge supports contain-
ing 50% Hoagland's solution. UnifOrmly ring labelled 14C-ethalfluralin
and 14C-trifluralin were used with specific activities of 2.78 uci/umole
and 2.53 uci/umole, respectively. Stock solutions were made by dissolving
each herbicide in methanol.

After 24 to 42 h acclimatization period, the most uniform seedlings
were selected. The remaining untreated nutrient solution was discarded
and 14 ml 0.33 x 10'6M 14C-ethalf1uralin or 0.33 x 10'6M 14C-trif1uralin
in 50% Hoagland's solution was added to each vial. Three plants, one per
vial, were used per treatment. Twenty-four and 72 h exposure times were
used. Two plants from each treatment were saved for autoradiography.

The remaining plants were pooled for quantitative 14C determination
described below.

At harvest, nutrient solution uptake by each plant was determined.

54

Plant roots were rinsed three times in distilled water and blotted dry.
Plants were placed on dry ice, freeze dried, and then autoradiographed
or divided into shoot and root for dry weight determination and extraction.

Plant parts were homogenized in 20 ml methanol in a Sorvall Omni-
Mixer at high speed for 5 min. Plant homogenates were filtered through
Whatman No. 4 filter paper and rinsed with methanol. The methanol-in-
soluble residue on Whatman No. 4 filter paper was freeze-dried prior to
combustion.

The methanol-insoluble residue was combusted by placing the sample
in a platinum basket into a 1000 m1 combustion flask and purging the
flask with oxygen for 1 min. After samples were ignited in a Nuclear
Chicago Mbdel 3151 semi-automatic combustion system, 14C02 was absorbed
in 15 m1 absolute ethanol plus ethanol-amine (95%) (2:1 v/v), injected
through a rubber septum stopper and stirred for 15 min. Aliquots (1 ml)
of the 14CO2 absorbant was radioassayed by liquid scintillation spectro-
metry using a 15 ml ACSR aqueous scintillation solution. Dissintegrations
per minute were calculated correcting for combustion efficiency.

The methanol-soluble extract was concentrated en vacuo to 1 ml.
This fraction was partitioned once with 10 ml of 9:1 (v/v) hexanezwater.
The aqueous layer was partitioned three additional times with 10 ml
hexane. These four hexane fractions were pooled and the volume reduced
under vacuum to 1 ml. A 100 pl sample of the water-soluble fraction was
radioassayed using 4 g PPO (2,5-diphenyloxazole) plus 50 mg dimethyl POPOP
(l,4-bis[2-(4-methyl-5-phenyloxazolyl)]-benzene) in 333 ml TRITON X-lOO
plus toluene and brought to a volumn of one 1. Samples (10 ul) of the
hexane-soluble fraction were radioassayed using the PPO plus POPOP scin-

tillation solution used for quantitative 14C-ethalfluralin and

55
14C-trifluralin determination. The second 10 ul sample was spotted on
250 um Silica Gel GF thin-layer chromatography plates. All plates in-
cluded standards for purity and parent herbicide identification. Thin-
1ayer plates were subjected to radioautography for 2 weeks and developed.

All data presented are the means of two experiments.

RESULTS AND DISCUSSION

Black nightshade plants from the CA seed source absorbed more 14C-
ethalfluralin and 14C-trifluralin, 24 and 72 h after treatment, than
plants from the MI source (Table 1). Considering plants from a single
seed source there was no difference in absorption between the two herbi-
cides. Plants grown from both black nightshade seed source, MI and CA,
have responded equally to preplant incorporated but not preemergence
ethalfluralin and trifluralin chemical treatments (15,16). Plants from
the Michigan seed source have been more susceptible to treatment by
ethalfluralin than trifluralin. Since absorption of the two herbicides
is similar, absorption does not appear to play a role in the differential
response to these two herbidides.

The 14C-distribution patterns for ethalfluralin and trifluralin re-
sulted in significant herbicide by plant part, seed source by plant part,
and application time by plant part interactions (Table 2, Figures 1 and
2). More 14C-ethalfluralin accumulated in the shoot regardless of
treatment than did 14C-trifluralin whereas the same concentration was
found in the root. The plants grown from the CA seed source accumulated
between three and four times more 14C-herbicide in both the shoot and

root than did the plants from the MI seed source. MOre 14C-herbicide

56
was found in the root than in the shoot regardless of plant seed source
or exposure time. However, more 14C was found in the root after 24 h
than 72 h. These data indicate that when discussion plants grown from
different seed sources, type of herbicide, or exposure time; the plant
parts must be considered. Plants grown from the MI seed source accumu-
lated less 14C than did those from the CA seed source, in both the shoot
and root.

Based on the metabolite separation obtained using the various extrac-
tion and TLC systems used by past researchers (2,4,5) we decided to uti-
lize the extraction procedure and carbon tetrachloride used twice TLC
development system of Golab (4). The hexane-soluble fraction of the
extraction procedure was subjected to TLC analysis for potential metabo-
lism detection due to the low amounts of radioactivity in the chlorofbrm
and aqueous extractant phases found by Golab (4).

Analysis of the percent disintegrations per minute per milligram
dry plant material found in the hexane and methanol-insoluble fractions
resulted in significant exposure time by seed source by plant part inter-
actions (Table 3). Data for the water-soluble fraction resulted in
significant herbicide effect and seed source by plant part interaction.
Plants from the CA and MI source accumulated less 14C in almost every
case in the shoot than in the root regardless of exposure time. There
was an increase in 14C found in the water-soluble fraction and in most
cases less 14C in the hexane-soluble fraction in the shoot as exposure
time progressed. Significantly more methanol-insoluble 14C-material was
fOund in the shoots of the plants grown from the MI seed source with 24
h exposure than any other treatment. There was more 14C in the methanol-

insoluble fraction as exposure time increased in the root portion of

57
plants grown from the CA seed source and shoots of plants from the MI
seed source. Thin-layer chromatography of the hexane-soluble fraction
indicated the presence of only the parent herbicides. Twenty-four hours
after treatment over 25% of the 14C in the shoots was in the water-
soluble fraction (Table 3). This concentration in the water-soluble
fraction increased with time. Ethalfluralin metabolism was more rapid
in the black nightshade from the CA seed source than from the MI seed
source. Ethalfluralin itself was converted more rapidly into water-solu-
ble metabolites than trifluralin; this difference was very evident in the
roots where up to six-fold differences were fOund indicating that the
double bond in the carbon chain of ethalfluralin may be more reactive
than the alkyl moiety of trifluralin.

Extraction procedures using parent compounds alone were examined.
The hexane and water fractions were radioassayed by liquid scintillation
spectrometry and over 98% of the total radioactivity was found in the
hexane fraction. This indicated that the 14C found in the water fraction
must be metabolites for both ethafluralin and trifluralin. These results
are consistent with those of Penner and Early (11) indicating rapid
metabolism of trifluralin into the water-soluble fraction of corn.

The increased absorption and translocation seen from ethalfluralin
relative to trifluralin to the shoot may be the reason for increased
black nightshade efficacy which has resulted from ethalfluralin in the
field. The rapid incorporation into the water fraction seen in plants
from the CA seed source regardless of herbicide or exposure may be the
reason why even though larger amounts were absorbed, the same response

was seen from plants of both seed sources.

10.

11.

12.

13.

14.

58

LITERATURE CITED

Barrentine, W.L. and G.F. Warren. 1971. Shoot zone activity of
trifluralin and nitraline. Weed Sci. 19:37-41.

Biswas, P.K. and W. Hamilton, Jr. 1969. Metabolism Of trifluralin
in peanuts and sweet potatoes. Weed Sci. 17:206-211.

Gentner, W.A. 1970. A technique to assay herbicide translocation
and a-fect on root growth. Weed Sci. 18:715-716.

Golab, T., R.J. Herberg, S.J. Parka, and J.B. Tepe. 1967. Meta-
bolism of carbon-12 trifluralin in carrots. J. Agric. Food Chem.
15:638-641.

Hawxby, K. and E. Basler. 1976. Effects of absorption and trans-
location of profluralin and dinitramine. Weed Sci. 24:545-548.

Hoagland, D.R. and D.I. Arnon. 1950. The water culture method for
growing plants without soil. California Agr. Exp. Sta. Cir. 347:

32 pp.

Kechersid, J.L., T.E. Boswell, and M.G. Merkle. 1969. Uptake and
translocation of substituted aniline herbicides in peanut seedlings.
Agron. J. 61:185-187.

Knake, E.L., A.P. Appleby, and W.R. Furtick. 1967. Soil incorpora-
tion and site of uptake of preemergence herbicides. Weed Sci. 15:
228-232.

Koren, E., D. Dahan, and M. Marmelstein. 1976. Ethafluralin - a
new residual herbicide in cotton. Phytoparasitica. 4(2):149.

Penner, D. 1971. Effect of temperature on phytotoxicity and root
uptake of several herbicides. Weed Sci. 19:571-575.

and R.W. Early. 1972. Action of trifluralin on chromatin

 

activity in corn and soybean. Weed Sci. 20:364-366.

Probst, G.W., T. Golab, R.J. Herberg, F.J. Holzer, S.J. Parka, C.
Van der Schans, and J.B. Tepe. 1967. Fate of trifluralin in
plants and soils. J. Agric. Food Chem. 14:592-599.

Skylakakis, G., B. Anastasiadis, J. Buendia, R.M. Bayo, Y. Oran,
and W.T. Waldrep. 1974. EL-l6l a new preplant incorporated herbi-
cide for control of grass and dicotyledonous weeds in cotton.
British Weed Control Conf. 2:795-800.

Strang, R.H. and R.L. Rogers. 1971. A microradioautographic study
of 1"C-trifluralin absorption. Weed Sci. 19:363-369.

15.

16.

59

Vandeventer, J.W., W.F. Meggitt, and Donald Penner. 1978.
Morphological and physiological variability in black nightshade
(Solanum gpp,). Weed Sci. (In preparation).

Vandeventer, J.W., W.F. Meggitt, and Donald Penner. 1978.
Morphological and physiological variability in black nightshade
(Solanum nigrum L.). WSSA Abstract #169.

60

Table 1. Absorption of 14C-ethafluralin and 14C-trifluralin by plants
from two black nightshade seed sources grown in nutrient
culture after 24 h and 74 h exposure.a

 

 

 

 

Ethalfluralin Trifluralin
Seed source 24 h 72 h 24 h 72 h
Michigan 2449 ab 1771 ab 3012 b 1661 a
California 7792 d 4809 c 5656 c 4655 c

 

aValues are expressed as total dpm/plant.
bMeans followed by common letters are not significantly different by
Duncan's multiple range test.

61

Table 2. Distribution of 14C—ethalfluralin and 14C-trifluralin in plants
grown from two black nightshade seed sources in shoot and root
over 24 and 72 h exposure.a

 

Plant parts

 

 

 

 

 

Shoot Root
14C-herbicide
Ethalfluralin 575 b 1329 c
Trifluralin 182 a 1443 c
Seed source
Michigan 231 a 854 b
California 526 c 1918 d
Exposure period (h)
24 367 a 1778 c
72 389 a 955 b

 

aValues are expressed as dpm/plant.
bMeans within treatment fOllowed by common letters are not significantly
different by Duncan's multiple range test.

62

a

.Hmou
omeen onHuHea m.ee6e:o no neonomme preeOHmnemHm woe one mnounoH eoeeou weH>ee eOHnoenm eoeo eHequ meeozn
.wono>ooon wa\amw Hence we neoonom me wommonmxo one moeHe>e

 

 

 

 

e mH eHHensHmnnn n ”H e e4 eHeeoeHHo6

n mm eHHeesHeHenom e HH o em nemnnonz

maxemww HeOHsoeo noon noonm oonsom woom
unem,neeHm

eOHuoenm none:

 

 

 

 

one m.m nm ~.on o.e ne o.m n «.mn m.~ oeee

eon m.m ne o.me m.me eon o.m woe N.me o.n~ oeenm eHeeemHHe6

one m.e nm N.mm w.m e ~.H n o.em w.~ ooee

e-e n.m o-n o.em m.mm o o.nm ne m.me m.m~ oeenm eemHnon eHHeesHeHen

e w.NH eon m.Hm ~.em no m.~ wee m.Hn ~.m~ .oeoe

e-e m.e e ~.m~ «.4e ne n.~ on N.me o.w< oneno eHeeeeHHe6

eon o.m wee o.~n w.H~ e-e m.e nmo o.Hm m.~H oeee

eo o.HH ne ~.e< o.me e-e ~.e m-o m.ee o.n~ oeone eemHnon eHHeHsHHHenom
eOHnoenm eOHuoenm eoHuoenm eonnoenm eOHnoenm eOHuoenm unem ooneom woom owHOHnnoz
oHneHomeH oeexo: none: oHneHomeH oeexo: nope: peeHm

Hoeeeuoz Hoeeeuoz

n we n e~

oaHu onemomxm

 

ee.onemomxo : an wee em nonme mooneom woom oweempemne xoeHn oz» sonm
exonm mneeHm mo mneoeomeoo noon wee nooem eH eHHeneHmHnuuueH wee eHHensHmHeenouueH mo monHHonepoz .m oHnen

63

Figure 1. Distribution of 14C—ethafluralin in plants grown from seed
collected in Michigan (A) and obtained from California (B).
The treated plant specimen is above the corresponding auto-
radiograph.

64

 

65

Figure 2. Distribution of 14C-trifluralin in plants grown from seed col-
lected in Michigan (A) and obtained from California (B). The
treated plant specimen is above the corresponding autoradio-

graph.

 

CHAPTER 4

SUMMARY AND CONCLUSIONS

Field studies were conducted to evaluate efficacy of several
herbicides for black nightshade control, activity on navy beans as a
primary crop and wheat as a rotational crop, and soil persistence. In
general, alachlor was most efficacious for black nightshade control while
little difference among herbicides was seen with respect to navy bean
yield and no differences among herbicides tested were seen on wheat
stand or yield. The application of chloramben or dinoseb either tank
mixed and preplant incorporated or preemergence resulted in no general
navy bean yield difference. The weed control obtained from chloramben
or dinoseb as additional herbicides often increased black nightshade con-
trol.

Black nightshade seed was Obtained from two sources, one native and
one from a California based seed supplier. Plants from these two seed
sources were grown and found to differ morphologically. Further examina-
tion of their physiology showed differences between plants from the two
seed sources with respect to germination, growth response to temperature,
and susceptibility to herbicides. Plants from these two seed sources
were found to be different species entirely, one was (MI) Solanum

americanum Mill. and the other (CA) was Solanum scabrum Mill. Both dif-

 

 

fered in susceptibility to ethalfluralin and trifluralin.
Plants from the CA seed source absorbed more 14C-ethalfluralin and

67

68
14C-trif1uralin than the plants from MI. Distribution of the 14C-herbi-
cides resulted in more 14C-ethalfluralin than 14C-trifluralin in the
shoots and the same concentrations of each in the roots. Twenty-four
hours after treatment metabolism was more rapid for 14C-ethafluralin
especially in plants from the CA seed source as indicated by the greater
concentration of 14C detected in the water-soluble fraction.

Differences in activity of these two substituted dinitroanilines on
black nightshade may be due to differing rates of herbicide metabolism.
Absorption did not appear responsible for differences in activity.

Weed researchers commonly order readily available seed for experi-
mentation, field and laboratory. Rarely in the literature has the weed
seed source been listed. This practice perpetuates thoughts that seed
collected near the researchers locale was used. The seed source must
be given or improper assumptions will continue. Herbicide labels are
written and often applicable nationwide whereas what is called by similar
names in dissimilar localities may cause incorrect herbicide usage by

farmers and researchers alike.

LIST OF REFERENCES

10.

11.

12.

LIST OF REFERENCES

Alex, J.P. and C.M. Switzer. Ontario Weeds. Ministry of Agric.
and Food Pub. No. 505. pp. 200.

 

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1978. Morphological and

 

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