ArticlePDF Available

Long-Term Control of Hedge Bindweed (Calystegia sepium L.) with Single, Tank Mixture, and Sequential Applications of Glyphosate, 2,4-D, and Dicamba

Authors:

Abstract and Figures

Hedge bindweed (Calystegia sepium L.) is a widespread troublesome perennial weed species that has strong rhizome regenerative capacity. Four pot trials with randomised, complete block designs were conducted in 2015 to evaluate long-term control of hedge bindweed using individual, tank mixture, and sequential applications of selected herbicides. Two different formulations of N-(phosphonomethyl) glycine (glyphosate; isopropylamine, trimesium salts) were applied at 2000 g active ingredient (a.i.) ha−1. Additionally, two synthetic auxins were applied as 3,6-dichloro-2-methoxybenzoic acid (dicamba) at 500 g a.i. ha−1 and the dimethylamine salt of (2,4 dichlorophenoxy)acetic acid (2,4-D) at 1000 g a.i. ha−1. Tank mixtures and sequential applications (12/24 h separation) of these different herbicides were also included. Long-term control of hedge bindweed, Calystegia sepium L., growth was evaluated 8 months after treatments, as comparisons of shoot and rhizome growth (biomass) between untreated and treated plants. There were no differences between the two formulations of glyphosate alone, with shoot and rhizome biomass reductions of 83% and 42%, respectively. Dicamba alone inhibited shoot and rhizome biomass by 86% and 67%, respectively. By itself, 2,4-D provided the greatest reductions in shoot and rhizome biomasses, 93% and 79%, respectively. Antagonism was seen in the tank mixtures of glyphosate and dicamba or 2,4-D. Tank mixtures were generally comparable to treatments of glyphosate alone, and were less effective compared to dicamba or 2,4-D alone. The greatest reduction of bindweed rhizome biomass was for sequential glyphosate trimesium salt followed by 2,4-D 12 h later, thus showing significantly greater efficacy over glyphosate isopropylamine salt (94% vs. 84%; p ≤ 0.05). These data for reductions of the growth of the rhizome biomass show that the sequential application of glyphosate followed by 2,4-D significantly improves long-term control of hedge bindweed.
Content may be subject to copyright.
agronomy
Article
Long-Term Control of Hedge Bindweed (Calystegia
sepium L.) with Single, Tank Mixture, and Sequential
Applications of Glyphosate, 2,4-D, and Dicamba
Aleš Kolmaniˇc 1, * , Robert Leskovšek 2and Mario Lešnik 3
1Crop Science Department, Agricultural Institute of Slovenia, 1000 Ljubljana, Slovenia
2Department of Agricultural Ecology and Natural Resources, Agricultural Institute of Slovenia,
1000 Ljubljana, Slovenia; robert.leskovsek@kis.si
3
Department of Plant Protection, Faculty of Agriculture and Life Sciences, University of Maribor, 2311 Hoˇce,
Slovenia; mario.lesnik@um.si
*Correspondence: ales.kolmanic@kis.si
Received: 20 July 2020; Accepted: 10 August 2020; Published: 13 August 2020


Abstract:
Hedge bindweed (Calystegia sepium L.) is a widespread troublesome perennial weed species
that has strong rhizome regenerative capacity. Four pot trials with randomised, complete block
designs were conducted in 2015 to evaluate long-term control of hedge bindweed using individual,
tank mixture, and sequential applications of selected herbicides. Two dierent formulations
of N-(phosphonomethyl) glycine (glyphosate; isopropylamine, trimesium salts) were applied
at 2000 g active ingredient (a.i.) ha
1
. Additionally, two synthetic auxins were applied as
3,6-dichloro-2-methoxybenzoic acid (dicamba) at 500 g a.i. ha
1
and the dimethylamine salt of
(2,4 dichlorophenoxy)acetic acid (2,4-D) at 1000 g a.i. ha
1
. Tank mixtures and sequential applications
(12/24 h separation) of these dierent herbicides were also included. Long-term control of hedge
bindweed, Calystegia sepium L., growth was evaluated 8 months after treatments, as comparisons of
shoot and rhizome growth (biomass) between untreated and treated plants. There were no dierences
between the two formulations of glyphosate alone, with shoot and rhizome biomass reductions
of 83% and 42%, respectively. Dicamba alone inhibited shoot and rhizome biomass by 86% and
67%, respectively. By itself, 2,4-D provided the greatest reductions in shoot and rhizome biomasses,
93% and 79%, respectively. Antagonism was seen in the tank mixtures of glyphosate and dicamba or
2,4-D. Tank mixtures were generally comparable to treatments of glyphosate alone, and were less
eective compared to dicamba or 2,4-D alone. The greatest reduction of bindweed rhizome biomass
was for sequential glyphosate trimesium salt followed by 2,4-D 12 h later, thus showing significantly
greater ecacy over glyphosate isopropylamine salt (94% vs. 84%; p
0.05). These data for reductions
of the growth of the rhizome biomass show that the sequential application of glyphosate followed by
2,4-D significantly improves long-term control of hedge bindweed.
Keywords:
hedge bindweed; perennial weeds; rhizome control; weed management; herbicide ecacy
1. Introduction
Hedge bindweed (Calystegia sepium L.) and field bindweed (Convolvulus arvensis L.)
(Convolvulaceae; morning glory) are two of the most troublesome perennial weeds in temperate
regions [
1
,
2
]. Indeed, field bindweed is considered as one of the most serious weed species throughout
the world, due to its adaptation to a wide range of habitats and cropping systems, which has already
caused serious yield losses and production cost increases worldwide [
3
,
4
]. Hedge bindweed is not as
widespread as field bindweed, although recent reports have shown that it has increased considerably
in terms of its abundance in the USA, Europe and other parts of the world [
5
,
6
]. This expansion
Agronomy 2020,10, 1184; doi:10.3390/agronomy10081184 www.mdpi.com/journal/agronomy
Agronomy 2020,10, 1184 2 of 15
appears to be associated with both the increasing areas that are under reduced tillage systems, and the
related changes in the use of herbicides with dierent spectra of activities, which tend to promote
late-germinating perennial weeds [7,8].
Both of these bindweed species can spread by means of vegetative (i.e., shoots, buds, rhizomes) or
generative (i.e., seeds) reproduction [
1
]. Their rapid regenerative capacities derive from their extensive
rhizome and root systems that can store large amounts of carbohydrates, which makes their long-term
control particularly dicult [
9
,
10
]. Field and hedge bindweed are closely related species [
11
,
12
].
The most important distinctive characteristic between these is that field bindweed generally spreads
by roots, while hedge bindweed propagates by extensive rhizome development and above-ground
runners [
13
]. Despite the dierences in their propagation organs, they show closely analogous survival
strategies in terms of rhizome and shoot sprouting, and below-ground resource storage [
10
]. With a
lack of relevant studies on the control of hedge bindweed, the background to field bindweed will also
be considered here.
Herbicide application is the most common management option for the control of hedge bindweed,
although mechanical and biological methods can also be used [
14
]. Mechanical control with
repeated soil cultivation is aimed at the depletion of the root and rhizome reserve, with success
here mainly relying on the correct timing of the tillage operations and the feasibility in the cropping
system
[15,16]
. Environmental concerns for herbicide use have also raised the need for alternative
control methods. Several potential bio-control agents have shown promising results, although none
have been commercialised [17,18].
A meta-analysis of the control of field bindweed within annual cropping systems reported that
herbicide use dominates in the literature, and that this represents an eective management strategy up
to 2 years post treatment [
14
].
The most common herbicides used for the control of field bindweed
are N-(phosphonomethyl)glycine (glyphosate), 3,6-dichloro-2-methoxybenzoic acid (dicamba),
(2,4 dichlorophenoxy)acetic acid (2,4-D), 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (picloram),
3,7-dichloro-8-quinolinecarboxylic acid (quinclorac), 6-amino-5-chloro-2-cyclopropylpyrimidine-4-
carboxylic acid (aminocyclopyrachlor), and 2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydro-1H-imidazol-
2-yl)nicotinic acid (imazapyr) [
14
,
19
,
20
]. Herbicides are, in most cases, eective for the short-term
suppression of field bindweed shoot biomass; however, long-term control and eradication is generally
not achieved [21].
Since its introduction in the 1970s, glyphosate has become one of the most widely used herbicides
in the world. Glyphosate use has increased since it was introduced for glyphosate-resistant crops in
1996, which lead to the expansion of no-tillage and conservation cropping systems [
22
,
23
]. Glyphosate is
a broad-spectrum systemic herbicide that is also used extensively for weed control in perennial fruit
tree crops, and in industrial areas and other amenity and domestic situations [
22
,
24
]. An apparent lack
of weed resistance to the glyphosate mode of action was believed to be a key feature of glyphosate.
However, 48 weed species across six continents have now been reported to be resistant to glyphosate [
25
].
Although there have not been any cases of field or hedge bindweed resistance to glyphosate reported
to date, the high natural tolerance to glyphosate of field bindweed, combined with the high application
rate and/or repeated use of glyphosate needed to overcome this tolerance, might well increase the
selection pressure and accelerate the development of resistance [
26
]. However, as can be observed for
glyphosate, there is generally more selection for resistance in highly susceptible weeds rather than
tolerant weeds [24,25].
One of the most eective groups of selective chemicals for the control of perennial broadleaf
weeds and brush are the synthetic auxins. For this herbicide group, dicamba and 2,4-D have been
widely used in agriculture for the past 50–70 years for the selective control of broadleaf weeds in cereal
and corn fields and pastures [
27
,
28
]. Among the several cases of confirmed resistance to dicamba and
2,4-D, none of the species from the morning glory family are known to have developed resistance
to these auxin herbicides [
25
]. However, there have been some reports of field bindweed biotypes
Agronomy 2020,10, 1184 3 of 15
with varied sensitivities to 2,4 D, and contrasting data on the control of field bindweed with synthetic
auxins have been reported [29,30].
Several morning glory species appear to have a natural tolerance to glyphosate [
26
,
31
] and diversity
in the susceptibility of field bindweed biotypes to glyphosate has been reported [
32
]. Tolerance to
specific herbicides can usually be overcome using herbicide mixtures or sequential applications of
dierent herbicides [
33
,
34
]. Enhanced activity on the tolerant weed species is achieved when a
similarly or more eective herbicide with a dierent mode of action is included in the mixture or
sequential treatment. There is also increasing evidence that the use of eective herbicide mixtures is a
better tactic for delaying resistance than rotating dierent herbicidal modes of action [
34
]. Besides,
the mixing of herbicides is generally the recommended practice, to increase the weed control spectrum,
although this requires compatibility of the tank mixture components [
35
]. However, interactions
between two or more herbicides might be antagonistic rather than additive, which will reduce or
increase, respectively, the combined ecacy; their synergism might also increase the expected additive
ecacy [
36
]. Sequential application also represents an eective tool for targeting not only troublesome
weed species, but also herbicide-resistant populations [
33
]. This strategy is commonly used to control
later-emerging weeds in systems with prolonged weed germination; however, additional herbicide
follow-up might also result in better long-term suppression of hedge bindweed.
As there are few relevant data available in the literature on the management of hedge bindweed,
the aim of the present study was to determine the long-term eects of herbicide control for the
inhibition of hedge bindweed growth. A better understanding of hedge bindweed responses to various
herbicides and the timing of their application(s) might provide knowledge for improved management
strategies and more eective control of this troublesome perennial weed species, especially when
considering reduced tillage systems. The objective of our study was, therefore, to determine the
ecacy of glyphosate, dicamba, and 2,4-D when used as single applications and as tank mixtures and
sequential applications, for the long-term inhibition of shoot and rhizome biomass of hedge bindweed
(Calystegia sepium L.).
2. Materials and Methods
A series of greenhouse pot trials was carried out at the Faculty of Agriculture and Life Sciences in
Maribor (Slovenia; 46
30
0
17.4” N, 15
37
0
34.6” E), from May 2015 to June 2016. A total of four trials
were set up, with untreated controls and seven dierent treatments in each. These were arranged as
randomised complete blocks with five replications. Each treatment consisted of 25 pots, and each
group of five pots was considered statistically as one repetition. The herbicide treatments were applied
as individual, tank mixture, and sequential applications, and included: two formulations of glyphosate
of ‘Boom efekt’ (48% isopropylamine salt; IPA-glyphosate; Albaugh TKI d.o.o.,) and Touchdown
system 4 (36% trimesium salt; TMS-glyphosate; Syngenta Crop Protection AG,); Banvel 480 S (48%
dicamba; Syngenta Crop Protection AG); and Herbocid (460 g/L 2,4-D; Nufarm GmbH & Co KG).
Moderate (glyphosate) to high (2,4-D and dicamba) herbicide doses were used in the study to obtain
long-term control of hedge bindweed and to test herbicide interactions at higher herbicide rates.
The details of these treatments are given in Table 1.
The plant material was collected in May 2015 from infested arable fields in the south-eastern
agricultural region of Slovenia, near the city of Kidriˇcevo (46
23
0
09.4” N 15
47
0
00.7” E). To minimise
the variability between the biotypes, the sampling was carried out from five adjacent fields. A 50 cm
×
50 cm and 25 cm deep square block was dug around the selected plants. The plants were lifted
and carefully washed to remove soil from the roots and rhizome system without damaging them.
After washing, the plants were placed in cold storage bins with wet sand and transported to the
experimental site. The plant material from the dierent fields was randomised and then planted into
plastic 10-L pots the same day. The pots were filled with a mixture of soil from a neighbouring field
and planting substrate (1:1; v/v). High uniformity among plants was achieved by the selection of only
plants with a well-developed (20 cm long) rhizome and a shoot with three to five leaves. The pots
Agronomy 2020,10, 1184 4 of 15
were placed in a greenhouse, watered, and allowed to grow for 5 months. Before the application of the
herbicides, the development stage of the plant and the above-ground and rhizome fresh biomass were
determined for the sample of 25 pots. The plant shoots were cut and the rhizomes were separated
from the soil with washing. The fresh biomass of the shoots and rhizomes were determined, and the
thickness and length of the rhizomes were also measured. The remaining untreated pots were left to
grow in the greenhouse for the following 8 months.
Table 1.
Treatments of the hedge bindweed applied in this study. For the active ingredients, glyphosates
were applied at 2000 g ha1, dicamba at 500 g ha1, and 2,4-D at 1000 g ha1.
Trial Design Order of Application
First Second
1 Control na na
Single-I IPA-glyphosate na
Single-II Dicamba na
Tank mix IPA-glyphosate +Dicamba na
Sequential-12-I IPA-glyphosate Dicamba
Sequential-12-II Dicamba IPA-glyphosate
Sequential-24-I IPA-glyphosate Dicamba
Sequential-24-II Dicamba IPA-glyphosate
2 Control na na
Single-I IPA-glyphosate na
Single-II 2,4-D na
Tank mix IPA-glyphosate +2,4-D na
Sequential-12-I IPA-glyphosate 2,4-D
Sequential-12-II 2,4-D IPA-glyphosate
Sequential-24-I IPA-glyphosate 2,4-D
Sequential-24-II 2,4-D IPA-glyphosate
3 Control na na
Single-I TMS-glyphosate na
Single-II Dicamba na
Tank mix TMS-glyphosate +Dicamba na
Sequential-12-I TMS-glyphosate Dicamba
Sequential-12-II Dicamba TMS-glyphosate
Sequential-24-I TMS-glyphosate Dicamba
Sequential-24-II Dicamba TMS-glyphosate
4 Control na na
Single-I TMS-glyphosate na
Single-II 2,4-D na
Tank mix TMS-glyphosate +2,4-D na
Sequential-12-I TMS-glyphosate 2,4-D
Sequential-12-II 2,4-D TMS-glyphosate
Sequential-24-I TMS-glyphosate 2,4-D
Sequential-24-II 2,4-D TMS-glyphosate
IPA-glyphosate, isopropylamine salt; TMS-glyphosate, trimesium salt; Sequential-12-I/II, -24-I/II, 12, 24 h between
sequential applications, as glyphosate first/second; na, not applicable.
According to interviews with farmers in this area, the crops generally included in the crop rotation
over the past 20 years had been maize, wheat, sugar beet, barley, and potato. The weed management
practices over this period had included the application of herbicides with dierent modes of action,
along with various cultivation operations according to conventional tillage systems. All of the farmers
used herbicides according to the principles of integrated crop management. Glyphosate had been used
occasionally on fallow land (i.e., cereal stubble), and synthetic auxins (e.g., dicamba, 2,4-D) had only
been rarely used on cereals and maize. There had been no apparent resistance of hedge bindweed to
herbicides, as reported by the farmers in the interviews.
Agronomy 2020,10, 1184 5 of 15
The herbicides for the present study were applied at the beginning of October 2015, when the plants
had developed 20 to 35 leaves and 35-cm- to 65-cm-long rhizomes with a thickness of 0.5 mm to 2.3 mm.
The fresh biomass shoot:rhizome ratio was ~3.5/1.0, and the theoretical leaf area index was ~1.42.
The plants were not at a vigorous growth stage and had partially developed flowers. The herbicides
were applied with an experimental sprayer (France Technoma Euro-Pulve). The spraying capacity
was 250 L ha
1
at an operating pressure of 3 bar. Droplets with a 125
µ
m to 145
µ
m volume median
diameter were generated using the required nozzle (Teejet XR 110015). Tap water with a hardness of
~14
dH was used. The air temperature and relative humidity at the time of the herbicide application(s)
were 22
C and 68%, respectively. After the herbicide application(s), the plants were left outside the
greenhouse to dry for 4 days. The pots were then placed back inside the greenhouse, and watered
according to need. During the winter period, the temperature in the greenhouse was from 1
C to
18 C, and the plants were not exposed to freezing temperatures.
The herbicide ecacies were calculated using the method of fresh plant biomass weights [
37
].
The shoots and rhizomes were separated from the soil and weighed in May 2016, 8 months after the
treatments. Only the green biomass of the living rhizomes was included in the samples, after the dried
and necrotic parts had been removed. The reduction ecacies of the herbicide treatments (HE) against
the above-ground (shoot) biomass and rhizome biomass were calculated as the ratio between the fresh
weights of the plant biomasses from the untreated and treated pots, as given in Equation (1):
HE [%] =((Weight of untreated control [g] Weight of treated [g])) /
(Weight of untreated control [g]) ×100 (1)
the interactions between the herbicides were calculated using the method of Colby [
38
], as given in
Equation (2).
E=100 ((100 Percent reduction by herbicide A) ×(100 Percent reduction by
herbicide B)) /100 (2)
the calculated values (E) for the herbicide mixtures were compared with the actual values (observed
response) for the herbicide mixtures. If the actual value for the mixture was greater than the calculated
value, then this indicated synergism, while a lower mixture value than the calculated value indicated
antagonism. Equal values here indicated simple additive eects [
37
]. The same principal was also
used for the analysis of interactions of herbicides for the sequential application where the calculated
values (E) were compared with the actual values (observed response) for the sequential application.
A random group analysis was performed using Statgraphics Centurion XVI (2011, Statpoint
Technologies, Warrenton, VA, USA), with a separate analysis performed for each experimental group.
Levene’s tests were used for the homogeneity of the variance. The data also underwent analysis of
variance (ANOVA) using the general linear model (
α
=0.05). The variables included in the model were
the blocks (n=5) as random eects, and the ecacies of the herbicide treatments (n=7) as fixed eects.
If ANOVA indicated statistical dierences, Tukey’s post hoc tests were used for multiple comparisons
of the herbicide treatments. The standard errors of the mean (SEM) are given to show the estimation of
the variance. The dierences between the IPA and TMS formulations of glyphosate were tested using
Student’s t-tests for independent sample comparisons (α=0.05).
3. Results
3.1. Reduction of Shoot Biomass Growth
Across the trials here, significant dierences between the herbicide applications were seen for
the reduction of shoot biomass (p
0.001; Table 2), with the detailed data for shoot biomass given in
Table 3.
Agronomy 2020,10, 1184 6 of 15
Table 2.
Statistics for sources of variation (ANOVA) for inhibition of hedge bindweed shoot and
rhizome biomass growth at 8 months after applications of IPA/TMA-glyphosate and dicamba or 2,4-D
(see Table 1).
Trial Application/Residual Statistics
df Shoot Biomass Rhizome Biomass
Sum of Squares pValue Sum of Squares pValue
1 IPA-glyphosate and dicamba 6 872.6 <0.001 6357.8 <0.001
Residual 24 568.9 642.3
2 IPA-glyphosate and 2,4-D 6 910.0 <0.001 8674.3 <0.001
Residual 24 309.4 1098.3
3 TMS-glyphosate and dicamba 6 779.9 <0.001 6341.5 <0.001
Residual 24 442.1 823.9
4 TMS-glyphosate and 2,4-D 6 838.6 <0.001 7254.7 <0.001
Residual 24 441.1 710.1
IPA-glyphosate, isopropylamine salt; TMS-glyphosate, trimesium salt.
Table 3.
Ecacy against hedge bindweed shoot biomass growth at 8 months after application(s)
of IPA/TMA-glyphosate and dicamba or 2,4-D (see Table 1). No significant dierences between
IPA-glyphosate and TMS-glyphosate within dicamba or 2,4-D sequential combinations (p>0.05;
Student’s t-tests for independent sample comparisons).
Design Ecacy Versus Shoot Biomass Growth
Glyphosate/Dicamba Glyphosate/2,4-D
IPA TMS IPA TMS
(%) Int. (%) Int. (%) Int. (%) Int.
Single-I 80.8 na 83.6 na 82.2 na 84.8 na
Single-II 85.6 na 87.0 na 95.0 na 91.6 na
Tank mix 90.8 – 90.6 – 92.0 – 91.8 –
Sequential-12-I 98.0 ++ 98.4 ++ 99.2 +99.4 ++
Sequential-12-II 87.8 – 85.2 – 89.8 – 85.2 –
Sequential-24-I 92.2 – 93.4 – 95.4 – 96.0 –
Sequential-24-II 89.4 – 90.8 – 89.0 – 90.8 –
SEM 2.1 1.9 1.6 1.9
IPA, IPA-glyphosate, isopropylamine salt; TMS, TMS-glyphosate, trimesium salt; Single-I, glyphosate alone; Single-II,
dicamba or 2,4-D alone; Tank mix, combinations mixed and applied together; Sequential-12-I/II, -24-I/II, 12, 24 h
between sequential applications, as glyphosate first/second; na, not applicable; SEM, standard error of the means for
inhibition including all treatments in the column; Int., Interactions with combined applications: –, antagonistic; +,
additive; ++, synergistic (according to Colby equation; Colby, 1967); for ecacy and interactions, see Materials and
Methods, Equations (1) and (2), respectively.
In the first trial (i.e., IPA-glyphosate, dicamba combinations), IPA-glyphosate followed by dicamba
12 h later showed significantly greater ecacy for the reduction of shoot biomass (98.0%) than
IPA-glyphosate (80.7%) or dicamba (85.6%) alone, and dicamba followed by IPA glyphosate 12 h later
(87.8%). IPA-glyphosate followed by dicamba 24 h later and tank mixtures of these two herbicides
were also significantly more eective against shoot biomass (92.2%, 90.9%, respectively) compared to
IPA-glyphosate alone.
In the second trial (i.e., IPA-glyphosate, 2,4-D combinations), IPA-glyphosate followed by 2,4-D
12 h later resulted in significantly greater ecacy for the reduction of shoot biomass (99.2%) compared
to IPA-glyphosate alone (82.1%) and to 2,4-D followed by IPA-glyphosate 12 h or 24 h later (89.8%,
89.0%, respectively). For IPA-glyphosate alone, significantly more shoot regrowth was seen compared
to the other treatments.
Agronomy 2020,10, 1184 7 of 15
In the third trial (i.e., TMS-glyphosate, dicamba combinations), TMS-glyphosate followed by
dicamba 12 h later showed significantly greater ecacy (98.4%) compared to TMS-glyphosate (83.6%)
or dicamba (86.9%) alone, and to dicamba followed by TMS-glyphosate 12 h later (85.2%).
The results of the fourth trial (i.e., TMS-glyphosate, 2,4-D combinations) showed that
TMS-glyphosate followed by 2,4-D 12 h later and 2,4-D followed by TMS-glyphosate 12 h later
were significantly more eective (99.4%, 96.0%, respectively) than TMS-glyphosate (84.8%) or
TMS-glyphosate followed by 2,4-D 24 h later (85.2%).
Of note here, there were no significant dierences between the IPA-glyphosate and TMS-glyphosate
formulations for these reductions of shoot biomass (Table 3). Here, the ecacies of the individual
herbicide applications averaged 81.5% for IPA-glyphosate alone, 84.2% for TMS-glyphosate alone,
86.3% for dicamba alone, and 93.3% for 2,4-D alone. Although the dierences were not significant,
overall, there were greater reductions of shoot biomass associated with the TMS salt of glyphosate
(Table 3). Additionally, in general, the tank mixtures were more eective compared to the individual
herbicide applications, as they attained 0.2% to 11% greater reductions of shoot biomass. For shoot
biomass reductions for the tank mixtures, these averaged 90.7% for glyphosate with dicamba, and 91.9%
for glyphosate with 2,4-D.
Overall, the greatest reductions of shoot biomass were obtained when glyphosate was followed
by dicamba or 2,4-D. Moreover, there were greater reductions compared to other treatments for both of
these sequential variants with time intervals of 12 h and 24 h. However, the most ecient reduction
was obtained with glyphosate followed by 2,4-D 12 h later. When this order was reversed to apply
dicamba or 2,4-D followed by glyphosate, the reductions of shoot biomass showed lower ecacies,
by 11.8% and 4.2% for the 12 h and 24 h sequential applications, respectively.
In the interaction analysis of the eects on shoot biomass growth of the herbicide mixtures
and these sequential applications, synergistic eects were obtained for both TMS-glyphosate and
IPA-glyphosate followed by dicamba 12 h later, and TMS-glyphosate followed by 2,4-D 12 h later.
A simple additive eect was obtained for IPA-glyphosate followed by 2,4-D 12 h later. Antagonistic
(i.e., non-additive) eects were observed for all of the other herbicide applications (Table 3).
3.2. Reduction of Rhizome Biomass Growth
For all of the trials, there were significant dierences in the reductions of rhizome biomass between
the herbicide applications (p
0.001; Table 2), with the detailed data for rhizome biomass given in
Table 4.
In the first trial (i.e., IPA-glyphosate, dicamba combinations), IPA-glyphosate followed by
dicamba 12 h later provided significantly greater reductions of rhizome biomass (80.4%) compared to
IPA-glyphosate alone (37.8%), dicamba alone (66.0%), the tank mixture of glyphosate and dicamba
(50.8%), and dicamba followed by IPA-glyphosate 24 h later (66.4%). The reductions of rhizome biomass
with IPA-glyphosate followed by dicamba 24 h later (70.4%) and dicamba followed by IPA-glyphosate
12 h later (73.6%) were also significantly greater compared to glyphosate alone (37.9%) and the tank
mixture of glyphosate and dicamba (50.9%).
In the second trial (i.e., IPA-glyphosate, 2,4-D combinations), IPA-glyphosate followed by 2,4-D
12 h later and the reverse order of 2,4-D followed by IPA-glyphosate 12 h later both showed significantly
greater reductions of rhizome biomass (84.0%, 82.8%, respectively) compared to IPA-glyphosate alone
(39.4%), the tank mixture of IPA-glyphosate and 2,4-D (52.6%), and 2,4-D followed by glyphosate
24 h later (68.4%). IPA-glyphosate alone and the tank mixture of IPA-glyphosate and 2,4-D were
significantly less eective compared to all of the other treatments.
In the third trial (i.e., TMS-glyphosate, dicamba combinations), TMS-glyphosate followed by
dicamba 12 h later provided a significantly greater reduction of rhizome biomass (93.0%) compared
to all of the other treatments. The ecacies of TMS-glyphosate followed by dicamba 24 h later
(75.4%) and dicamba followed by TMS-glyphosate 12 h later (75.0%) were significantly greater
compared to TMS-glyphosate alone (45.4%) or the tank mixture of glyphosate and dicamba (62.2%).
Agronomy 2020,10, 1184 8 of 15
For glyphosate alone, there was significantly lower rhizome biomass suppression compared to all of
the other treatments.
Finally, for the results of the fourth trial (i.e., TMS-glyphosate, 2,4-D combinations), glyphosate
followed by 2,4-D 12 h later was significantly more eective (93.6%) compared to all of the other
treatments. In contrast, for TMS-glyphosate alone, the reductions of rhizome biomass were significantly
lower compared to all of the treatments and, for tank mixture of TMS-glyphosate with 2,4-D,
the reductions of rhizome biomass were significantly lower compared to all of the sequential applications
and 2,4-D alone.
Table 4.
Ecacy against hedge bindweed rhizome biomass growth at 8 months after application(s)
of IPA/TMA-glyphosate and dicamba or 2,4-D (see Table 1). Bold, significant dierences between
IPA-glyphosate and TMS-glyphosate within dicamba or 2,4-D sequential combinations (p
0.05;
Student’s t-tests for independent sample comparisons; α=0.05).
Design Ecacy Versus Rhizome Biomass Growth
Glyphosate/Dicamba Glyphosate/2,4-D
IPA TMS IPA TMS
(%) Int. (%) Int. (%) Int. (%) Int.
Single-I 37.8 na 45.4 na 39.4 na 47.0 na
Single-II 66.0 na 67.4 na 82.0 na 75.4 na
Tank mix 50.8 62.2 – 52.6 – 59.0 –
Sequential-12-I 80.4 ++ 93.0 ++ 84.0 93.6 ++
Sequential-12-II 73.6 – 75.0 – 82.8 – 79.4 –
Sequential-24-I 70.4 – 75.4 – 71.4 82.4
Sequential-24-II 66.4 – 73.6 – 68.4 – 77.6 –
SEM 2.3 2.6 3.0 2.4
IPA-glyphosate, isopropylamine salt; TMS-glyphosate, trimesium salt; Single-I, glyphosate alone; Single-II, dicamba
or 2,4-D alone; Tank mix, combinations mixed and applied together; Sequential-12-I/II, -24-I/II, 12, 24 h between
sequential applications, as glyphosate first/second; na, not applicable; SEM, standard error of the means for inhibition
including all treatments in the column; Int., Interactions with combined applications: –, antagonistic; ++, synergistic
(according to Colby equation; Colby, 1967); for ecacy and interactions, see Materials and Methods, Equations (1)
and (2), respectively.
In the IPA-glyphosate versus TMS-glyphosate comparisons using dicamba for the reduction of
rhizome biomass, glyphosate followed by dicamba 12 h later and tank mixtures of glyphosate and
dicamba showed significant dierences (p
0.01). Here, TMS-glyphosate was associated with greater
ecacies than IPA-glyphosate. Similar benefits were seen for reductions of rhizome biomass for
TMS-glyphosate over IPA-glyphosate in the 2,4-D trials, with significant dierences for glyphosate
followed by 2,4-D 12 h (p
0.05) and 24 h (p
0.01) later, and 2,4-D followed by glyphosate 24 h later
(p0.05).
As can be seen from the ecacy data in Table 4for the reduction of rhizome biomass, the averages
for the individual herbicide applications were 38.6% for IPA-glyphosate, 46.2% for TMS-glyphosate,
66.7% for dicamba, and 78.7% for 2,4-D. On average, the tank mixtures were less eective compared to
the individual herbicides alone, at 56.5% for glyphosate and dicamba, and 55.8% for glyphosate and
2,4-D. Additionally, in the overall comparisons of the reduction of rhizome biomass associated with
IPA-glyphosate and TMS-glyphosate use with dicamba and 2,4-D, these showed greater benefits for
TMS-glyphosate (18.3%, 10.8%, respectively).
The sequential applications of these herbicides showed the greatest reduction of rhizome biomass.
Overall, the greatest ecacies were seen for glyphosate followed 12 h later by dicamba (93.0%) or 2,4-D
(93.6%). Conversely, if dicamba or 2,4-D were followed by glyphosate, the final rhizome biomasses were
greater (19.3%, 15.2%, respectively). On average, for the sequential applications of TMS-glyphosate
versus IPA-glyphosate with dicamba and 2,4-D, TMS-glyphosate showed greater reductions of
rhizome biomass, with increases of 8.2% and 7.9%, respectively, over IPA-glyphosate. Furthermore,
Agronomy 2020,10, 1184 9 of 15
the comparisons of the ecacies that showed significant dierences for the reduction of rhizome
biomass between IPA-glyphosate and TMS-glyphosate were always in favour of TMS-glyphosate, as it
was 12.6% greater when followed by dicamba 12 h later, 9.6% greater when followed by 2,4-D 12 h
later and, finally, 11.0% greater when followed by 2,4-D 24 h later. Furthermore, TMS-glyphosate was
also more ecient for the reduction of rhizome biomass even for the 24 h sequential applications.
Dierences in reductions were also seen for these ecacies between 12 h and 24 h for 2,4-D followed by
IPA-glyphosate (14.4%) compared to TMS-glyphosate (1.8%). For dicamba followed by IPA-glyphosate
or TMS-glyphosate, a similar reduction of the ecacies for the applications 12 h after to 24 h after were
seen (IPA: 7.2%; TMS, 1.4%).
The results of the interaction analysis of the eects on rhizome biomass of the herbicide mixtures
and these sequential applications showed synergistic eects for IPA-glyphosate followed by dicamba
12 h later and TMS-glyphosate followed by dicamba or 2,4-D 12 h later. Antagonistic interactions were
observed for all of the other herbicide applications (Table 4).
4. Discussion
Due to the lack of relevant studies on the control of hedge bindweed in particular, we include here a
reference to the more studied field bindweed for comparisons and discussion. As these two bindweeds
are closely related, we would expect small physiological and morphological variations aecting the
biological ecacy of the tested herbicides. However, this presumption remains speculative, particularly
for glyphosate, as significant dierences in the natural tolerance of field bindweed compared to the
glyphosate-susceptible Japanese false bindweed (Calystegia hederacea) were reported [26]. Dierences
in tolerance to glyphosate among the biotypes of field bindweed have also been reported [
39
],
which indicated a high variability of tolerance to glyphosate among these species.
Modern production systems with conservation and no-tillage practices are favouring specialisation
and weed management simplification, especially for herbicide-resistant crops. Such simplification
for weed control can be seen in the abandonment of good weed management practices (rotation
of herbicide active ingredient) and increasing reliance on glyphosate [
40
]. The chemical control of
hedge bindweed is therefore also shifting towards continual selection pressure from the same class of
herbicide, and such actions usually contribute to rapid shifts in weed species populations or resistance
development [
40
42
]. Additionally, a lack of genuine new modes of action of herbicides and a decline in
the available active ingredients [
43
] have increased the dependence on only a few herbicide groups for
the control of hedge bindweed. To delay the development of resistance to the few remaining herbicides,
tank mixtures or sequential applications can be recommended [
33
]. However, the eectiveness of these
methods for the control of hedge bindweed are not known.
The data from the present study show that a relatively high reduction of shoot biomass growth
8 months after the application of these herbicides can be achieved, generally regardless of whether they
are applied individually, in mixtures, or sequentially. These findings are in agreement with a number
of studies reporting on eective (>90%) above-ground biomass suppression of the closely related field
bindweed across dierent herbicides [
21
,
32
,
44
46
]. Limitations to the reduction of the above-ground
biomass of hedge bindweed obtained by glyphosate over longer time periods were seen in the present
study. Applications of glyphosate alone and sequential applications with glyphosate follow-up were
less eective for the reduction of the above-ground growth of hedge bindweed 8 months after their
application, compared to dicamba and 2,4-D applied alone or following glyphosate.
The simple assumption of the successful control of hedge bindweed based on the eective
suppression of the above-ground biomass is usually not reliable for such perennial weeds with extensive
rhizome systems. Even after complete destruction of the above-ground shoots, the stored reserves in
the rhizomatous root system enables the development of regenerative shoots, even after relatively long
periods of time. For the eective control of hedge bindweed with herbicides, good translocation of
herbicide and high biological ecacy to the rhizome system are thus needed. However, as demonstrated
for field bindweed, even when these criteria have been met, continual treatments over longer periods
Agronomy 2020,10, 1184 10 of 15
are usually required to eectively overcome this regeneration from the root system [
14
]. In the present
study, herbicides and rates were selected with the aim to achieve the long-term rhizome reduction of
hedge bindweed. However, there were live rhizomes in most of the pots after the removal of the soil
even when there was little or no above-ground growth seen. Indeed, there were weak correlations
between the control of the above-ground versus rhizome biomasses after 8 months, even for the
herbicides that resulted in almost no shoot growth 8 months after their application (data not shown).
The greatest rhizome biomass reductions at 8 months after herbicide applications were for the
sequential applications of TMS-glyphosate followed by 2,4-D or dicamba 12 h later. Indeed, synergistic
interactions were obtained for these sequentially applied dicamba or 2,4-D at 12 h (although only
after TMS-glyphosate), while there were antagonistic interactions for the other sequential applications.
Similarly, greater control of field bindweed was reported for sequential herbicide applications compared
to tank mixtures or the herbicides applied alone in other studies [
21
,
47
]. Furthermore, the improved
control of grasses and broadleaf weeds with glyphosate used in sequential applications was also
reported [
48
50
]. The reductions of the rhizome biomass of hedge bindweed in the present study
were higher compared to those for field bindweed in the studies by Stone et al. and Hoss et al. [
21
,
46
].
This can be partly attributed to the limitations of the pot experiments, where the ratio between the
rhizome and shoot biomass diers from that seen under field conditions, which was here in favour
of the above-ground biomass. Consequently, the herbicide concentrations that entered the rhizome
tissues might have been higher here, thus apparently enhancing the herbicide performance.
The data here for the sequential applications of these herbicides suggest that, after the initial
application of glyphosate, sucient membrane integrity was maintained in the treated leaves for at
least 24 h, to thus sustain the translocation flow to allow the plants to take up and translocate the
sequentially applied auxins to the rhizomes. However, the reductions of ecacy seen here show
that there might have been decreased indices of uptake or translocation of dicamba or 2,4-D when
applied 24 h after the glyphosate. As glyphosate can inhibit the transport of auxins and enhance auxin
oxidation [
24
], the translocation of dicamba or 2,4-D applied 24 h later might have been more aected
than when applied only 12 h after glyphosate, which would have resulted in the lower reductions
of rhizome biomass observed. When dicamba or 2,4-D was applied first with the later application
of glyphosate, even smaller reductions of rhizome biomass were observed. As dicamba and 2,4-D
can rapidly disrupt the plant carbon flow [
51
,
52
], the translocation of sequentially applied glyphosate
(which is translocated using this mechanism) might well be aected by this. This is supported in
a study for the control of the annual broadleaf weed species kochia (Kochia scoparia (L.) Schrad.),
where the plant translocation system was inhibited when glyphosate and dicamba were applied as a
tank mixture [53].
For the rhizome system, the individual herbicide treatments were generally less eective compared
to the sequential applications. Dicamba and 2,4-D showed greater rhizome biomass reductions
compared to glyphosate. Several studies have partly attributed variations in the herbicide performances
to dierences in agro-climatic conditions, aecting the uptake and translocation of herbicides [
20
,
47
].
Regardless of the salt formulation, when glyphosate was applied alone, it showed the lowest reductions
of hedge bindweed rhizome biomass across these trials. The application of a similar dose of
2.24 kg ha1
glyphosate reduced the infestation of field bindweed by 24% under conditions of low humidity, and by
60% under humid conditions [
39
], which again indicates that environmental conditions have an
important eect on the ecacy of glyphosate. One of the weaknesses of glyphosate is its lower ecacy
against broadleaf weeds when applied at low and moderate doses [
24
]. With the moderate dose of
glyphosate used in the present study, this might explain the relatively low reductions of biomass
achieved. However, even with higher doses of glyphosate applied alone, consistent ecacy against
field bindweed has not been maintained across a number of studies [
15
,
21
]. DeGennaro and Weller [
32
]
explained the contrasting data in their study according to the natural variation of susceptibility to
glyphosate across field bindweed biotypes. Indeed, they needed a four-fold higher rate of glyphosate
treatment (4.5 kg ha
1
) to show ecacy against glyphosate-tolerant populations. The reasons for
Agronomy 2020,10, 1184 11 of 15
such dierences in susceptibility to glyphosate were further elaborated on, with detailed discussion
of the cellular mechanisms that influence dierential glyphosate sensitivities in the bindweed field
biotypes [
26
,
39
]. Additionally, the amount of glyphosate transported from the source leaves to the
sink tissues can be self-limiting, because the glyphosate mechanism of action inhibits the transport of
assimilates [
54
]. Other related species of hedge bindweed, such as Ipomoea spp., can also show higher
natural tolerance to glyphosate [55].
Some dierences among the glyphosate formulations were observed in the present study,
with greater ecacy for glyphosate in the form of its trimesium salt. These dierences were observed
across the four trials, and they cannot simply be explained by random variability or by sampling
error. Potentially, the uptake and translocation of these two glyphosate salts dier, allowing one
to have greater ecacy against the hedge bindweed rhizomes. Based on these findings, it would
appear that for the TMS formulation there would have been slower collapse of the cell photosystem
activity, allowing translocation to be sustained for longer. Longer cell activity and translocation to
the rhizome system with TMS-glyphosate would also explain the greater ecacy of the sequentially
applied dicamba and 2,4-D. However, we are not able to confirmation this possibility, or indeed other
explanations, here and there remains no definitive report in the literature.
The tank mixtures of glyphosate with dicamba and 2,4-D in the present study showed antagonistic
eects that resulted in a lower reduction of rhizome biomass compared to the individual applications
of dicamba and 2,4-D, and their sequential applications in general. The ecacies of the tank mixtures
against rhizome biomass were only comparable to glyphosate applied alone. This eect was not seen for
the reductions in above-ground biomass, with similar antagonistic interactions seen. Contrasting results
of the performance of glyphosate and synthetic auxins as tank mixtures were reported [
20
,
52
,
56
,
57
].
In the studies, these herbicide mixtures showed either synergistic or antagonistic eects when applied
to field bindweed and other perennial weeds. These inconsistent results might also indicate that the
interactions between these two herbicide groups are weed species specific. Antagonism between
glyphosate and 2,4-D was reported against wild oat (Avena fatua L.), wheat (Triticum aestivum L.),
barley (Hordeum vulgare L.), and johnsongrass (Sorghum halepense L.) [
56
,
58
]. Antagonistic interactions
between glyphosate and dicamba were also seen against kochia and johnsongrass [
53
]. Furthermore,
antagonistic interactions between glyphosate and dicamba were observed on both glyphosate- and
dicamba-resistant and susceptible kochia, as a result of the decreased translocation of these two
herbicides [
53
]. Conversely, glyphosate supplemented with dicamba had positive eects, with a
greater reduction of horseweed seen [
59
]. Green [
60
] noted that reduced rates of herbicides used in
tank mixtures can also produce synergistic interactions, although this was not confirmed for hedge
bindweed in the present study.
The mixing of herbicides is generally the recommended practice to reduce herbicide use while
maintaining weed infestation at acceptable levels [
60
]. Furthermore, if improved ecacies of mixtures
against weeds are obtained with reduced doses of the component herbicides, crop production can
be more cost eective [
36
,
61
]. The use of the available herbicides as tank mixtures is considered as
one of the proactive approaches to address the development of resistance in broadleaf weeds [
62
].
It has also been reported that the mixing of herbicides with dierent modes of action can overcome
specific bindweed tolerances to selected herbicides [
36
]. Further increases in the use of herbicide
mixtures against weeds is expected, with the introduction of multiple herbicide-resistant crops with
dicamba or 2,4-D plus glyphosate and/or glufosinate resistance [
63
]. Compared to the annual rotation
of herbicides with dierent modes of action, there are also some indications that herbicide mixtures
are more eective in preventing the development of resistance [
33
,
64
]. However, based on the results
of the present study, tank mixtures of glyphosate and dicamba or 2,4-D would not be recommended
against hedge bindweed. The sequential application of glyphosate with dicamba or 2,4-D 12 h later
provided the greatest ecacy of hedge bindweed here, and so this should be an eective method to
reduce even heavy infestations of hedge bindweed. However, our findings from pot experiments
should also be tested under field conditions to validate this.
Agronomy 2020,10, 1184 12 of 15
5. Conclusions
This study shows that hedge bindweed can be eectively managed without glyphosate, as dicamba
or 2,4-D applied alone provided greater ecacy against rhizome biomass compared to glyphosate
alone. In treatments with the sequential application of glyphosate followed by dicamba or 2,4-D,
further reductions in rhizome biomass were achieved. This can reduce the necessary applications and
herbicide input in the long term, especially in the conservation and no-tillage systems mainly relying
on chemical weed control of hedge bindweed with glyphosate. Such an approach can be viable for spot
treatments or for areas under extreme infestation with hedge bindweed, where repeated treatments
over longer periods of time will be needed. As well as improved eciency, this strategy also provides
preventive anti-resistance mitigation measures, as alternative modes of action are included in these
sequential treatments. Antagonism was observed for the tank mixtures of glyphosate and dicamba
or 2,4-D, and so these mixtures were less eective compared to individual applications of dicamba
or 2,4-D. Although these applications were only made during the autumn here, early tillage and
mechanical methods should also be a part of integrated management strategies for hedge bindweed,
which will further improve the long-term control of this troublesome perennial weed species.
Author Contributions:
Conceptualization, A.K., R.L., and M.L.; methodology, M.L.; formal analysis, A.K.;
investigation, M.L.; writing—Original draft preparation, A.K. and M.L.; writing—Review and editing, R.L.;
funding acquisition, M.L. All authors have read and agreed to the published version of the manuscript.
Funding:
This research was funded by the Core Financing of the Slovenian Research Agency, Ljubljana, Slovenia,
entitled “Sustainable Agriculture” (P4-0133) and “Agrobiodiversity” (P4-0072).
Acknowledgments:
The authors would like to dedicate this work to the memory of Stanislav Vajs. The authors are
also grateful for the hard physical work of various students that was necessary for the establishment of these trials.
Conflicts of Interest:
The authors declare no conflict of interest. The funders had no role in the design of the
study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to
publish the results.
References
1.
Holm, L.G.; Plucknett, D.L.; Pancho, J.V.; Herberger, J.P. The World’s Worst Weeds: Distribution and Biology,
1st ed.; University Press of Hawaii: Honolulu, HI, USA, 2007; 609p.
2.
Schroeder, D.; Mueller-Schaerer, H.; Stinson, C.S. A European weed survey in 10 major cropping systems to
identify targets for biological control. Weed Res. 1993,33, 449–458. [CrossRef]
3.
Weber, E.; Gut, D. A survey of weeds that are increasingly spreading in Europe. Agron. Sustain. Dev.
2005
,
25, 109–121. [CrossRef]
4.
Wiese, A.F.; Salisbury, C.D.; Bean, B.W.; Schoenhals, M.G.; Amosson, S. Economic evaluation of field bindweed
(Convolvulvus arvensis) control in a winter wheat-fallow rotation. Weed Sci. 1996,44, 622–628. [CrossRef]
5.
Boldt, P.E.; Rosenthal, S.S.; Srinivasan, R. Distribution of field bindweed and hedge bindweed in the USA.
J. Prod. Agric. 1998,11, 377–381. [CrossRef]
6.
Schmid, R.; Walsh, N.G.; Entwhisle, T.J. Flora of Victoria. Vol. 4. Dicotyledons: Cornaceae to Asteraceae.
Taxon 2000,49, 344. [CrossRef]
7.
Mehrtens, J.; Schulte, J.M.; Hurle, K. Unkrautflora in Mais—Ergebnisse eines Monitorings in Deutschland.
Gesunde Pflanz. 2005,57, 206–218. [CrossRef]
8.
Meissle, M.; Mouron, P.; Musa, T.; Bigler, F.; Pons, X.; Vasileiadis, V.P.; Otto, S.; Antichi, D.; Kiss, J.; P
á
link
á
s, Z.;
et al. Pests, pesticide use and alternative options in European maize production: Current status and future
prospects. J. Appl. Entomol. 2010,134, 357–375. [CrossRef]
9.
Marsalis, M.A.; Renz, M.J.; Jones, S.H.; Lauriault, L.M. Managing field bindweed in sorghum-wheat-fallow
rotations. Crop Manag. 2008,7, 1–9. [CrossRef]
10.
Willeke, L.; Krähmer, H.; Claupein, W.; Gerhards, R. Sprouting ability and seasonal changes of sugar
concentrations in rhizomes of Calystegia sepium and roots of Convolvulus arvensis.J. Plant. Dis. Prot.
2015
,
122, 133–140. [CrossRef]
Agronomy 2020,10, 1184 13 of 15
11.
Carine, M.A.; Russel, S.J.; Santos-Guerra, A.; Francisco-Ortega, J. Relationships of the Macaronesia and
Mediterranean floras: Molecular evidence for multiple colonizations into Macaronesia and back-colonization
of the continent in Convolvulus (Convolvulaceae). Am. J. Bot. 2004,91, 1070–1085. [CrossRef] [PubMed]
12.
Stefanovic, S.; Krueger, L.; Olmstead, R.G. Monophyly of the Convolvulaceae and circumscription of their
major lineages based on DNA sequences of multiple chloroplast loci. Am. J. Bot.
2002
,89, 1510–1522.
[CrossRef] [PubMed]
13.
Kraehmer, H.; Baur, P. Rhizomes. In Weed Anatomy, 1st ed.; Kraehmer, H., Baur, P., Eds.; Wiley-Blackwell:
Chichester, UK, 2013; pp. 206–210. [CrossRef]
14.
Davis, S.; Mangold, J.; Menalled, F.; Orlo, N.; Miller, Z.; Lehnho, E. A meta-analysis of field bindweed
(Convolvulus arvensis) management in annual and perennial systems. Weed Sci.
2018
,66, 540–547. [CrossRef]
15.
Callihan, R.H.; Eberlein, C.V.; McCarey, J.P.; Thill, D.C. Field Bindweed: Biology and Management;
Bulletin No. 719
; University of Idaho, Cooperative Extension System, College of Agriculture: Moscow, ID,
USA, 1990; 8p.
16.
Rask, A.M.; Andreasen, C. Influence of mechanical rhizome cutting, rhizome drying and burial at dierent
developmental stages on the regrowth of Calystegia sepium.Weed Res. 2007,47, 84–93. [CrossRef]
17.
Pfirter, H.A.; Ammon, H.U.; Guntli, D.; Greaves, M.P.; D
é
fago, G. Towards the management of field bindweed
(Convolvulus arvensis) and hedge bindweed (Calystegia sepium) with fungal pathogens and cover crops.
Integr. Pest Manag. Rev. 1997,2, 61–69. [CrossRef]
18.
D
é
fago, G.; Ammon, H.U.; Cagan, L.; Draeger, B.; Greaves, M.P.; Guntli, D.; Hoeke, D.; Klimes, L.; Lawrie, J.;
Moënne-Loccoz, Y.; et al. Towards the biocontrol of bindweeds with a mycoherbicide. BioControl
2001
,46,
157–173. [CrossRef]
19.
Lindenmayer, R.B.; Nisses, S.J.; Westra, P.P.; Shaner, D.L.; Brunk, G. Aminocyclopyrachlor absorption,
translocation and metabolism in field bindweed (Convolvulus arvensis). Weed Sci.
2013
,61, 63–67. [CrossRef]
20.
Westra, P.; Chapman, P.; Stahlman, P.W.; Miller, S.D.; Fay, P.K. Field bindweed (Convolvulus arvensis) control
with various herbicide combinations. Weed Technol. 1992,6, 949–955. [CrossRef]
21.
Stone, A.E.; Peeper, T.F.; Kelley, J.P. Ecacy and acceptance of herbicides applied for field bindweed
(Convulvulus arvensis) control. Weed Technol. 2005,19, 148–153. [CrossRef]
22.
Duke, S.O.; Powles, S.B. Glyphosate: A once-in-a-century herbicide. Pest Manag. Sci.
2008
,64, 319–325. [CrossRef]
23.
Pardo, G.; Mart
í
nez, Y. Conservation agriculture in trouble? Estimating the economic impact of an eventual
glyphosate prohibition in Spain. Planta Daninha 2019,37, e019197994. [CrossRef]
24.
Baylis, A.D. Why glyphosate is a global herbicide: Strengths, weaknesses and prospects. Pest Manag. Sci.
2000,56, 299–308. [CrossRef]
25.
Heap, I. International Survey of Herbicide Resistant Weeds. Available online: http://www.weedscience.org
(accessed on 8 April 2020).
26.
Huang, Z.; Liu, Y.; Zhang, C.; Jiang, C.; Huang, H.; Wei, S. Molecular basis of natural tolerance to glyphosate
in Convolvulus arvensis.Sci. Rep. 2019,9, 8133. [CrossRef] [PubMed]
27.
Monaco, T.J.; Weller, S.C.; Ashton, F.M. Weed Science: Principles and Practices, 4th ed.; Wiley-Blackwell:
New York, NY, USA, 2002; pp. 291–293.
28.
Mithila, J.; Hall, J.C.; Johnson, W.G.; Kelley, K.B.; Riechers, D.E. Evolution of resistance to auxinic herbicides:
Historical perspectives, mechanisms of resistance, and implications for broadleaf weed management in
agronomic crops. Weed Sci. 2011,59, 445–457. [CrossRef]
29. Whitworth, J.W. The reaction of strains of field bindweed to 2,4-D. Weed Sci. 1964,12, 57–58. [CrossRef]
30.
Schoenhals, M.G.; Wiese, A.F.; Wood, M.L. Field bindweed (Convolvulus arvensis) control with imazapyr.
Weed Technol. 1990,4, 771–775. [CrossRef]
31.
Pazuch, D.; Trezzi, M.M.; Guimaraes, A.C.D.; Barancelli, M.V.J.; Pasini, R.; Vidal, R.A. Evolution of natural
resistance to glyphosate in morning glory populations. Planta Daninha 2017,35, e017159430. [CrossRef]
32.
DeGennaro, P.F.; Weller, S.C. Dierential susceptibility of field bindweed (Convolvulus arvensis) biotypes to
glyphosate. Weed Sci. 1984,32, 472–476. [CrossRef]
33.
Davidson, B.; Cook, T.; Chauhan, B.S. Alternative options to glyphosate for control of large Echinochloa colona
and Chloris virgata plants in cropping fallows. Plants 2019,8, 245. [CrossRef]
34.
Beckie, H.J. Herbicide-resistant weeds: Management tactics and practices. Weed Technol.
2006
,20,
793–814. [CrossRef]
Agronomy 2020,10, 1184 14 of 15
35.
Altman, J. Pesticide Interactions in Crop Production. In Pesticide Interactions in Crop Production. Beneficial and
Deleterious Eects, 1st ed.; Altman, J., Ed.; Taylor and Francis Group: CRC Press: Boca Raton, FL, USA, 1993;
pp. 3–13. [CrossRef]
36. Damalas, C.A. Herbicide tank mixtures: Common interactions. Int. J. Agric. Biol. 2004,6, 209–212.
37. Rao, V.S. Principles of Weed Science, 2nd ed.; CRC Press: Boca Raton, FL, USA, 2000; pp. 497–500.
38.
Colby, S.R. Calculating synergistic and antagonistic responses of herbicide combinations. Weeds
1967
,15,
20–22. [CrossRef]
39.
Westwood, J.H.; Weller, S.C. Cellular mechanisms influence dierential glyphosate sensitivity in field
bindweed (Convolvulus arvensis) biotypes. Weed Sci. 1997,45, 2–11. [CrossRef]
40.
Johnson, W.G.; Davis, V.M.; Kruger, G.R.; Weller, S.C. Influence of glyphosate-resistant cropping systems on
weed species shifts and glyphosate-resistant weed populations. Eur. J. Agron.
2009
,31, 162–172. [CrossRef]
41.
Shaner, D.L. The impact of glyphosate-tolerant crops on the use of other herbicides and on resistance
management. Pest Manag. Sci. 2000,56, 320–326. [CrossRef]
42. Culpepper, A.S. Glyphosate-induced weed shifts. Weed Technol. 2006,20, 277–281. [CrossRef]
43. Beckie, H.J.; Tardif, F.J. Herbicide cross resistance in weeds. Crop Prot. 2012,35, 15–28. [CrossRef]
44.
Derscheid, L.A.; Strizke, J.F.; Wright, W.G. Field bindweed control with cultivation, cropping, and chemicals.
Weed Sci. 1970,18, 590–596. [CrossRef]
45.
Sherrick, S.L.; Holt,H.A.; Hess, F.D. Effects of adjuvants and environment during plant development on glyphosate
absorption and translocation in field bindweed (Convolvulus arvensis). Weed Sci. 1986,34, 811–816. [CrossRef]
46.
Hoss, N.E.; Al-Khatib, K.; Peterson, D.E.; Loughin, T.M. Ecacy of glyphosate, glufosinate, and imazethapyr
on selected weed species. Weed Sci. 2003,51, 110–117. [CrossRef]
47.
Enloe, S.F.; Westra, P.; Nissen, S.J.; Miller, S.D.; Stahlman, P.W. Use of Quinclorac Plus 2,4-D for controlling
field bindweed (Convolvulus arvensis) in fallow. Weed Technol. 1999,13, 731–736. [CrossRef]
48.
Widderick, M.J.; Bell, K.L.; Boucher, L.R.; Walker, S.R. Control by glyphosate and its alternatives of
glyphosate-susceptible and glyphosate-resistant Echinochloa colona in the fallow phase of crop rotations in
subtropical Australia. Weed Biol. Manag. 2013,13, 89–97. [CrossRef]
49.
Borger, C.P.; Hashem, A. Evaluating the double knockdown technique: Sequence, application interval,
and annual ryegrass growth stage. Aust. J. Agric. Res. 2007,58, 265–271. [CrossRef]
50.
Werth, J.; Walker, S.; Boucher, L.; Robinson, G. Applying the double knock technique to control
Conyza bonariensis.Weed Biol. Manag. 2010,10, 1–8. [CrossRef]
51.
Grossmann, K. Auxin herbicides: Current status of mechanism and mode of action. Pest Manag. Sci.
2010
,
66, 113–120. [CrossRef]
52.
Flint, J.L.; Barrett, M. Eects of glyphosate combinations with 2,4-D or dicamba on field bindweed. Weed Sci.
1998,37, 12–18. [CrossRef]
53.
Ou, J.; Thompson, C.R.; Stahlman, P.W.; Bloedow, N.; Jugulam, M. Reduced translocation of glyphosate and
dicamba in combination contributes to poor control of Kochia scoparia: Evidence of herbicide antagonism.
Sci. Rep. 2018,8, 5330. [CrossRef]
54.
Shaner, D.L. Role of translocation as a mechanism of resistanceto glyphosate. Weed Sci.
2009
,57, 118–123. [CrossRef]
55.
Corbett, J.L.; Askew, S.D.; Thomas, W.E.; Wilcut, J.W. Weed ecacy evaluations for bromoxynil, glufosinate,
glyphosate, pyrithiobac, and sulfosate. Weed Technol. 2004,18, 443–453. [CrossRef]
56.
Flint, J.L.; Barrett, M. Antagonism of glyphosate to johnsongrass by 2,4-D and dicamba. Weed Sci.
1998
,37,
700–705. [CrossRef]
57.
Hydrick, D.E.; Shaw, D.R. Eects of tank-mix combinations of nonselective foliar and selective soil-applied
herbicides on three weed species. Weed Technol. 1994,8, 129–133. [CrossRef]
58.
O’Sullivan, P.A.; O’Donovan, J.T. Interaction between glyphosate and various herbicides for broad leaf weed
control. Weed Res. 1980,20, 255–260. [CrossRef]
59.
Eubank, T.W.; Poston, D.H.; Nandula, V.K.; Koger, C.H.; Shaw, D.R.; Reynolds, D.B. Glyphosate-resistant
horseweed (Conyza canadensis) control using glyphosate, paraquat, and glufosinate-based herbicide programs.
Weed Technol. 2008,22, 16–21. [CrossRef]
60.
Green, J.M. Maximizing herbicide efficiency with mixtures and expert systems. Weed Technol.
1991
,5,
894–897. [CrossRef]
Agronomy 2020,10, 1184 15 of 15
61.
Gressel, J. Synergizing Pesticides to Reduce Use Rates. In Pest Control with Enhanced Environmental Safety;
Duke, S.O., Plimmer, J.R., Eds.; American Chemical Society: Washington, DC, USA, 1993; Volume 524,
pp. 48–61. [CrossRef]
62.
Beckie, H.J.; Reboud, X. Selecting for weed resistance: Herbicide rotation and mixture. Weed Technol.
2009
,
23, 363–370. [CrossRef]
63.
Green, J.M. The rise and future of glyphosate and glyphosate-resistant crops. Pest Manag. Sci.
2018
,74,
1035–1039. [CrossRef]
64.
Diggle, A.; Neve, P.; Smith, F. Herbicides used in combination can reduce the probability of herbicide
resistance in finite weed populations. Weed Res. 2003,43, 371–382. [CrossRef]
©
2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Weed control is a crucial aspect in many conservation agriculture systems given that costs and time savings from avoiding tillage are closely linked to the use of effective and environmental friendly herbicides. This has led to the widespread use of glyphosate in farms, as it is a broad-spectrum, easily degradable, low- cost herbicide. The recent debate on the safety of glyphosate and on the excessive use of chemical herbicides in food production has caused concern on farmers about the possible economic effects of a virtual ban on glyphosate. The aim of this paper is to estimate the costs associated with an eventual prohibition of glyphosate in Spanish conservation agriculture areas. The costs of different alternative weed control strategies for herbaceous and tree crops were calculated: i) substitution of glyphosate in chemical control; ii) minimum tillage; iii) conventional tillage; and iv) natural or planted vegetal groundcovers. The results show that banning glyphosate would increase the costs of chemical control by 40% for herbaceous and by 57% for tree crops. However, conventional tillage would be a cheaper option for herbaceous because costs increase by 10% compared to current techniques. Our estimations suggest that the ban on glyphosate would have a negative impact on the economic profitability of farms and also on other non-economic advantages derived from conservation farming techniques.
Article
Full-text available
The over-reliance on the herbicide glyphosate for knockdown weed control in fallows under minimum and zero-till cropping systems has led to an increase in populations of glyphosate-resistant weeds. Echinochloa colona and Chloris virgata are two major grass weeds in the cropping regions of northern New South Wales and southern Queensland, Australia, that have become harder to kill due to a steady rise in the occurrence of glyphosate-resistant weed populations. Therefore, to help growers contain these hard to kill fallow weeds, an alternate approach to glyphosate application is needed. With this purpose in mind, a pot study was carried out during the summer seasons of 2015 and 2016 at the Tamworth Agricultural Institute, Tamworth, NSW, Australia, to evaluate the efficacy of tank mixtures and sequential applications of Group H (4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor), Group C (inhibitors of photosynthesis at photosystem II), Group A (ACCase inhibitors) and Group L (photosystem I inhibitor) herbicides on late tillering E. colona and C. virgata plants. These herbicide groups are a global classification by the Herbicide Resistance Action Committee. Highly effective results were achieved in this study using combinations of Groups H, C, A and L herbicides applied as tank mixtures for controlling large E. colona plants. Additionally, sequential applications of Group H, C and A herbicides followed by (fb) paraquat were shown to be very effective on large E. colona plants. Late tillering C. virgata plants were generally well controlled by tank mixtures, and sequential applications proved to be highly effective on this grass weed as well. Haloxyfop in combination with paraquat as a tank mixture, via sequential application or as a stand-alone treatment, was highly effective for C. virgata control; however, using combinations of herbicide groups is the preferred choice when combating herbicide resistant weed populations. There was a clear synergy shown using Group H, Group C and Group A herbicides in combination with the Group L herbicide paraquat in this study for controlling advanced E. colona and C. virgata plants. These combinations were shown to be successful on plants grown under glasshouse conditions; however; these treatments would need to be tested on plants grown in a field situation to show whether they will be a useful solution for farmers who are trying to control these weeds in fallow.
Article
Full-text available
Convolvulus arvensis is a troublesome weed that is naturally tolerant to glyphosate. This weed tolerates glyphosate at a rate 5.1 times higher than that of glyphosate-susceptible Calystegia hederacea. Glyphosate-treated C. arvensis plants accumulated less shikimic acid than C. hederacea plants. The overexpression of EPSPS genes from the two species in transgenic Arabidopsis thaliana resulted in similar glyphosate tolerance levels. qPCR of genomic DNA revealed that the EPSPS copy number in C. arvensis was approximately 2 times higher than that in C. hederacea. Moreover, glyphosate treatment caused a marked increase in EPSPS mRNA in C. arvensis compared to C. hederacea. GUS activity analysis showed that the promoter of CaEPSPS (CaEPSPS-P) highly improved GUS expression after glyphosate treatment, while no obvious differential GUS expression was observed in ChEPSPS-P transgenic A. thaliana in the presence or absence of glyphosate. Based on the obtained results, two coexisting mechanisms may explain the natural glyphosate tolerance in C. arvensis: (i) high EPSPS copy number and (ii) specific promoter-mediated overexpression of EPSPS after glyphosate treatment.
Article
Full-text available
Field bindweed ( Convolvulus arvensis L.) is a persistent, perennial weed species that infests a variety of temperate habitats around the globe. To evaluate the efficacy of general management approaches and impacts on crop yield and to identify research gaps, we conducted a series of meta-analyses using published studies focusing on C. arvensis management in annual cropping and perennial systems. Our analysis of 48 articles (560 data points) conducted in annual systems indicated that 95% of data points measured efficacy over short time frames (within 2 yr of treatment). Furthermore, only 27% of data points reported impacts of C. arvensis management on crop yield. In annual systems, herbicide control dominated the literature (~80% of data points) and was an effective management technique up to 2 yr posttreatment. Integrated management, with or without herbicides, and three nonchemical techniques were similarly effective as herbicide at reducing C. arvensis up to 2 yr posttreatment. In addition, integrated approaches, with or without herbicides, and two nonchemical techniques had positive effects on crop yield. There were few differences among herbicide mechanism of action groups on C. arvensis abundance in annual systems. There were only nine articles (28 data points) concerning C. arvensis management in perennial systems (e.g., pasture, rangeland, lawn), indicating more research effort has been directed toward annual systems. In perennial systems, biocontrol, herbicide, and non-herbicide integrated management techniques were equally effective at reducing C. arvensis , while competition and grazing were not effective. Overall, our results demonstrate that while chemical control of C. arvensis is generally effective and well studied, integrated and nonchemical control practices can perform equally well. We also documented the need for improved monitoring of the efficacy of management practices over longer time frames and including effects on desired vegetation to develop sustainable weed management programs.
Article
Various combinations of crops, herbicides, and tillage were evaluated for field bindweed ( Convolvulus arvensis L.) control in western South Dakota. Four crop rotations (continuous wheat ( Triticum aestivum L.), wheat-fallow, wheat-sorghum ( Sorghum vulgare Pers.), and wheat-sorghum-fallow) were modified by the application of (2,4-dichlorophenoxy)acetic acid (2,4-D) and/or the use of post-harvest tillage. Intensive cultivation and 2,4-D treatment were used to aid in the control of field bindweed in forage crops grown on a long-term basis and in conjunction with small grain rotations. Treatment with 2,4-D in a grain crop and with non-selective herbicides after harvest were tested. Crops were planted the succeeding 2 or 3 years and observed for effect of chemical residue. The established plants could be essentially eliminated while utilizing adapted crop rotations. The use of 2,4-D alone or in combination with cultivation made it possible to reduce the stand of field bindweed (20.7 to 22.2 shoots/sq yd) 90% or more in 3 years in all rotations. A ¾-lb/A rate of 2,4-D in June prevented seed production, killed susceptible plants, and weakened the remaining plants, but a follow-up treatment of 2,4-D in the fall, post-harvest cultivation, or post-harvest treatment with herbicides such as 2,3,6-trichlorobenzoic acid (2,3,6-TBA), 3,6-dichloro- o -anisic acid (dicamba), or 4-amino-3,5,6-trichloropicolinic acid (picloram) was necessary to kill them.
Article
Biotypes of field bindweed ( Convolvulus arvensis L. ♯ ³ CONAR) identified in Indiana varied widely in susceptibility to glyphosate [ N -(phosphonomethyl)glycine] but not to 2,4-D [(2,4-dichlorophenoxy)acetic acid] or bentazon [3-isopropyl-1 H -2,1,3-benzothiadiazin-4(3 H )-one 2,2-dioxide] in field tests. Significant differences in injury to two of the biotypes occurred with glyphosate applied at 1.12 to 4.48 kg ai/ha in greenhouse tests. Differences of greater than 70% in injury rating, root and shoot dry weight, and shoot regrowth dry weight occurred between the two biotypes at 2.24 kg/ha glyphosate. The susceptibility of the tolerant biotype at 2.24 kg/ha glyphosate was decreased by 40% as it increased in age, while the susceptible biotype sustained complete foliar necrosis when treated at all plant ages tested. Susceptibility differences between the two biotypes could not be correlated to differences in leaf stomatal or epidermal cell number. These studies suggested that the variable control of field bindweed observed in the field may be due to the occurrence of biotypes within a given population of this weed which differ in their susceptibility to glyphosate.
Article
Absorption and translocation of glyphosate [ N -(phosphonomethyl)glycine] with and without adjuvants were examined in field bindweed ( Convolvulus arvensis L. # CONAR) to develop an understanding of the influence of selected adjuvants and environment before application on glyphosate activity. Light intensity and humidity during plant development resulted in differences in ¹⁴ C-glyphosate absorption. When applied in water or with an oxysorbic (20 POE) (polyoxyethylene sorbitan monolaurate) adjuvant, an average of 9% of the glyphosate was absorbed in plants grown in high light intensity, low humidity (HLLH) before treatment, compared to an average of 21% in plants grown in low light, high humidity (LLHH) before treatment, respectively. Amounts of epicuticular wax on HLLH field bindweed were almost three times as great as on LLHH leaves and may explain absorption differences. No differences in glyphosate absorption were observed between glyphosate applied with oxysorbic or no adjuvant even though the oxysorbic adjuvant effectively reduces surface tension. Absorption was increased two- to threefold with a polyethoxylated tallow amine adjuvant (MON 0818) compared to no adjuvant. Unlike absorption without adjuvant or with oxysorbic adjuvant, there were few absorption differences in plants grown in different environments before application. Absorption continued for 24 to 36 h after application regardless of adjuvant. Reductions in MON 0818 concentration and subsequent necrosis resulted in increased movement of radioactivity away from the site of application.
Article
Greenhouse studies were conducted to determine the basis for reduced johnsongrass control when glyphosate was applied in mixtures with 2,4-D or dicamba. Glyphosate was applied to johnsongrass at 0.28, 0.56, 0.84, and 1.12 kg/ha alone and in combination with 2,4-D or dicamba at 0.14, 0.28, 0.14, or 0.56 kg/ha. Johnsongrass shoot and root fresh weights measured 4 weeks after treatment were higher when glyphosate was applied with 2,4-D (0.28 kg/ha glyphosate) or dicamba (0.28 kg/ha or 0.56 kg/ha glyphosate) compared to glyphosate applied alone at these rates. The antagonism of johnsongrass control was not observed with combinations of some of the higher glyphosate rates with 2,4-D (0.56 or 0.84 kg/ha glyphosate) or dicamba (0.84 or 1.12 kg/ha glyphosate). The reduction of glyphosate activity on johnsongrass occurred when any of four forms of 2,4-D or two forms of dicamba were added to the glyphosate spray mixture. Glyphosate uptake into johnsongrass leaves and subsequent translocation to the roots was reduced by the presence of 2,4-D or dicamba. The reduced glyphosate uptake and translocation could account for the decreased toxicity of glyphosate to johnsongrass when applied with 2,4-D or dicamba.
Chapter
The concept of crop safening against nonselective herbicides with the use of chemical treatments is credited to Otto L. Hoffman. 1 During his experiments in the late 1940s, he noticed that injury of tomatoes (Lycopersicon esculentum Mill.) by the herbicide 2,4-D was reduced if the plants were previously treated with the inactive analogue of the herbicide, 2,4,6-T. These pioneering efforts led to the development and commercialization of crop safeners, which are chemical compounds that exhibit limited phytotoxicity and protect crops against herbicide injury. They are usually applied as seed treatments or as prepackaged tank mixtures with herbicides. Under field conditions, unsafened susceptible plants, whether weed or crop, are eliminated when exposed to a lethal dose of the herbicide. The great advantage of safeners is their ability to control weeds that grow in botanically related crops, e.g., wild oats (Avena fatua L.) in cultivated oats (Avena sativa L.), red rice in cultivated rice (both Oryza sativa L.), or shattercane in grain sorghum (both Sorghum bicolor (L.) Moench). To date, the industry has successfully developed crop safeners for use in corn, sorghum, and rice. 2-23 Safeners for protection of broadleaf crops have been tested for eventual commercial use, but the attempts have not yet been successful. 2, 3, 24 Crop safeners for herbicides have been reviewed by many authors. 1-4, 25-30 Other terms for crop safeners include “herbicide antidotes”, “herbicide safeners”, “protectants”, “antagonists”, or “modifiers”. 24. © 1993 by CRC Press, Inc. CRC Press is an imprint of Taylor & Francis Group, an Informa business.