HERBICIDAL EFFICACY OF ACETIC ACID AND CITRIC ACID BASE ON BROAD LEAF WEEDS OF MEDICINAL CROPS FIELDS

Abstract

The study aims to determine the effectiveness of acetic acid based formula on broad leaf weeds grown in medicinal crop fields. Two experiments were conducted, i.e. on small plots (2 m x 3 m) of a farmer’s field in Ciapus, Bogor and on a larger plot (2 m x 8 m) at the Cicurug Experimental Station, Sukabumi. The formula consisted of a mixture of acetic acid + NaCl (AG) and acetic acid + citric acid (AC), and formulas of VAC, VACG which were enriched with wood vinegar (V). As control was a commercial synthetic herbicide 2,4 D amine. The acetic acid base formulas applied at two concentrations 10 and 15%, while 2,4-diamine was followed the recommendation (0.3%) using a knapsack sprayer with a flat-fan nozzle tip. Weed vegetations were observed visually before and at 2, 4, 6, and 8 weeks after treatments. Weed severity was recorded using a 0-4 scales (0 = 0-5% mortality ; 1 = 20-50% weeds died ; 3 = 50-75% eradicated and 4 = 75-100% weed were eradicated), as well as re-growth and dry weight of the weeds. The first and second experiment showed that AC, AG, VAC and VACG applied at 10 and 15% were effective in controlling broadleaf weeds. Mechanism of action the formula is a contact poison. Its effectiveness is equivalent to 2,4-D amine treatment dose of 1.5 l ha-1. Repeated application is necessary to prolong the effect of herbicide.

Full text

137
HERBICIDAL EFFICACY OF ACETIC ACID AND CITRIC ACID BASE ON BROAD
LEAF WEEDS OF MEDICINAL CROPS FIELDS
Keefektifan herbisida berbasis asam asetat dan asam sitrat terhadap gulma berdaun lebar pada
lahan tanaman obat
Sri Rahayuningsih and Supriadi
Indonesian Spices and Medicinal Crops Research Institute
Jalan Tentara Pelajar No. 3 Bogor 16111
Telp 0251-8321879 Faks 0251-8327010
balittro@litbang.pertanian.go.id
yayuk.balittro@litbang.pertanian.go.id
(diterima 08 Agustus 2014, direvisi 10 Oktober 2014, disetujui 27 November 2014)
ABSTRACT
The study aims to determine the effectiveness of acetic acid based formula on broad leaf weeds grown in medicinal
crop fields. Two experiments were conducted, i.e. on small plots (2 m x 3 m) of a farmer’s field in Ciapus, Bogor and on
a larger plot (2 m x 8 m) at the Cicurug Experimental Station, Sukabumi. The formula consisted of a mixture of acetic
acid + NaCl (AG) and acetic acid + citric acid (AC), and formulas of VAC, VACG which were enriched with wood vinegar
(V). As control was a commercial synthetic herbicide 2,4 D amine. The acetic acid base formulas applied at two
concentrations 10 and 15%, while 2,4-diamine was followed the recommendation (0.3%) using a knapsack sprayer
with a flat-fan nozzle tip. Weed vegetations were observed visually before and at 2, 4, 6, and 8 weeks after
treatments. Weed severity was recorded using a 0-4 scales (0 = 0-5% mortality ; 1 = 20-50% weeds died ; 3 = 50-75%
eradicated and 4 = 75-100% weed were eradicated), as well as re-growth and dry weight of the weeds. The first and
second experiment showed that AC, AG, VAC and VACG applied at 10 and 15% were effective in controlling broadleaf
weeds. Mechanism of action the formula is a contact poison. Its effectiveness is equivalent to 2,4-D amine treatment
dose of 1.5 l ha-1. Repeated application is necessary to prolong the effect of herbicide.
Key words: Herbicide, acetic acid, citric acid, NaCl, broad leaf weeds
ABSTRAK
Penelitian ini bertujuan untuk mengetahui efektivitas formula herbisida berbasis asam asetat pada gulma berdaun
lebar yang tumbuh di ladang pada lahan petani di Ciapus, Bogor, dan skala lebih besar (plot berukuran 2 m x 8 m) di
Kebun Percobaan Cicurug, Sukabumi. Perlakuan yang diuji adalah campuran asam asetat + NaCl (AG) dan asam asetat
+ asam sitrat (AC), serta formula yang diperkaya dengan cuka kayu (vinegar; V). Sebagai kontrol adalah herbisida
sintetis komersial 2,4 D amina. Konsentrasi herbisida berbasis asam asetat disemprotkan dengan semprotan gendong
pada konsentrasi 10 dan 15%, sedangkan 2,4-diamin mengikuti rekomendasi (0,3%). Vegetasi rumput diamati secara
visual sebelum dan pada 2, 4, 6, dan 8 minggu setelah perlakuan. Keparahan gulma dicatat dalam skala 0-4 (0 =
mortalitas 0-5% ; mortalitas gulma 1 = 20-50% ; 3 = mortalitas gulma 50-75% dan 4 = mortalitas gulma 75-100% ,
serta pertumbuhan ulang dan berat kering gulma. Hasil percobaan pertama dan kedua menunjukkan bahwa formula
AC, AG, VAC, dan VACG yang diaplikasikan pada konsentarsi 10 dan 15% efektif terhadap gulma berdaun lebar.
Mekanisme cara kerja formula adalah racun kontak. Efektivitasnya setara dengan 2,4-D pada dosis 1,5 l ha-1.
Aplikasi berulang diperlukan untuk memperpanjang efek herbisida.
Kata kunci: Herbisida, asam asetat, asam sitrat, NaCl, gulma daun lebar
INTRODUCTION
Synthetic herbicides are important
chemicals in controlling various types of weeds of
medicinal crops. The use of herbicides worldwide
is around 49.6% of the total pesticides
(Merrington et al., 2002). World pesticide demand
has been projected to increase from $ 26 billion in
2004 to $ 28.4 billion in the year 2009 with a

Bul. Littro, Volume 25, Nomor 2, Desember 2014
138
growth rate of 1.7% per year (World Pesticide,
2005 in Irianto and Johanis, 2009). The increasing
use of herbicides is in line with efforts to meet the
global demand for sustainable food, feed and
energy (food, feed and fuel). The most widely
used of herbicides are glyphosate (N-
phosphonomethyl glycine), paraquat (paraquat
dichloride), and 2,4-D (2, 4 dichloro phenoxy
acetic acid). Although glyphosate is determined as
the most least toxic (Duke and Powels, 2008), but
recently there has been reports of various
negative effects of glyphosate on human healths
(FoEE, 2013).
The economic value of herbicides in
agriculture is very large, especially in highly
intensive agriculture that uses minimal labour. For
example, the herbicide glyphosate is very effective
in controlling grasses and broadleaf weeds. Weed
is often a major problem in crop production
systems of food, vegetables, medicinal, and
ornamental crops (Hasanuddin et al., 2000).
Efforts to get a safer herbicides, such as the use of
plant materials and biological, are being actively
studied in various countries. However, the results
are still limited because of its effectiveness is still
far lower than the synthetic herbicides. However,
studies showed that synthetic herbicide used can
be minimized by mixing with more environmental
chemicals, such as wood vinegar, acetic acid or
citric acid (Tiilikkala et al., 2010). Wood vinegar
(liquid pyrolysis) is the result of condensation of
liquid vapor of the combustion process of wood
into charcoal at high temperatures (400-500°C)
(Tiilikkala et al., 2010). Wood vinegar has long
been used in China, Egypt, Greece and India for
agricultural purposes, such as fertilizers, pesticides
and plant growth stimulants. The main content of
liquid smoke is acetic acid and methanol, as well
as several other compounds, such as propanoic
acid, acetone, methyl acetone, acetaldehyde, allyl
alcohol, furan and furfural, and formic, propionic
and butyric (Payamara, 2011; Tiilikkala et al.,
2010).
Research results of Abouziena et al. (2009)
showed that acetic acid (5%), citric acid (10%), and
clove oil (45.6%) were effective against broadleaf
weeds, while the narrow leaf weeds required a
higher concentration of acetic acid (30%). Acetic
acid is a contact type herbicide and its effect can
be seen within hours (1-2 hours after application).
Another advantage of acetic acid herbicide is
biodegradable, so it does not lead to residues on
crops. Controlling weeds with a herbicide mixture
of clove oil (318 l ha-1) and vinegar (636 l ha-1) is
quite effective (83%) for controlling weeds in
crops of corn, onions and potatoes (Evans and
Bellinder, 2009).
An effort to reduce the pressure on the
emergence of resistant weeds is to use different
types of herbicide alternating or mixing two or
more kinds of different types of herbicides. The
practice of mixing herbicides divergent types in
tanks before being sprayed has been reported,
especially to improve the effectiveness, slowing
the process of emergence of resistant weeds,
reduce herbicide residues, reducing the volume of
herbicides and cost required (Damalas, 2004). Rico
et al. (2007) showed that the mixing of cyhalotop-
butyl + bentazone herbicides with wood vinegar
(1: 1000) significantly increased the effectiveness
of the herbicides while increasing rice yields.
Panjehkeh and Alamshahi (2011) showed that the
combination of phenmedipham + chloridazon was
more effective against broadleaf weeds in sugar
beet, without damaging to the leaves and tubers.
This study aims to determine the
effectiveness of the mixture of acetic acid + NaCl
(AG) and acetic acid+citrate (AC) formulas against
several types of broadleaf weeds grown in
medicinal crop fields.
MATERIALS AND METHODS
Weed identification
Weeds grew on the experimental sites
were identified based on their morphological
characteristics and their scientific names were

Sri Rahayuningsih and Supriadi : Herbicidal Efficacy of Acetic Acid and Citric Acid Base on Broad Leaf Weeds of Medicinal Crops Fields
139
confirmed by using the identification book of
weeds in Indonesia.
First experiment
Acetic acid, NaCl, acid citrate, and
commercial herbicide 2,4-D were obtained from
local chemical suppliers. The experiment was
conducted on a farmer’s land at Ciapus, Bogor in
2012. The experiment was a randomized block
designed, consisting of six treatments, such as a
mixture of acetic acid + NaCl (AG) and acetic acid +
acid citrate (AC ) with a concentration of 10 and
15%. Used as the formula of commercial
herbicides 2,4-D amine 0.3% and the untreated
control. Treatment was repeated three times.
Treatment plot size was 2 m x 3 m. Spraying is
done using a knapsack sprayer with a flat-fan
nozzle so that drops of the herbicide solution
were evenly spread on the target weeds.
Second experiment
This experiment was conducted at the
Cicurug Experimental Station, Sukabumi. Field
conditions were evenly grown with natural weeds.
Plot size was 2 m x 8 m. Thirteen treatments were
evaluated, such as (1) Formula AG 15%, (2)
Formula AG 20%, (3) Formula AC 15%,(4) Formula
AC 20%, (5) Formula ACG 15%, (6) Formula ACG
20%, (7) Formula VACG 15%, (8) Formula VACG
20%, (9) Glyphosate, (10) Paraquat, (11) 2,4-D
amine, (12) mechanical daytime, and (13) Control.
The treatment was designed as a randomized
block design (RBD), repeated three times.
Application of the formula AG, AC and
ACG performed three times with interval one
week, while the commercial herbicide was applied
once. Manual weeding was done during twice
with a three weeks interval.
Parameters measured were (a) the
percentage of the target weed mortality, (b) weed
re-growth, and (c) dry weight of cut weeds.
Parameter observation
Prior to application of herbicide, weed
vegetation was observed visually to determine the
types of dominant weeds. After the application,
parameters measured were (a) weed mortality of
0-4 scales observed in 2, 4, 6, and 8 weeks after
application (MSA), (b) percentage of weed re-
growth, and (c) new weed emergence. The weed
mortality rate was calculated as follows. Scale 0
means up to 0-5% mortality; scale 1 (lowest
category) means 5-20% weed died; scale 2 (mild
category) means 20-50% weeds died; scale 3
(medium category) means 50-75% eradicated; and
scale 4 (severe category) means 75-100% weed
were eradicated. (Komisi Pestisida, 2000;
Pujisiswanto, 2011).
The effectiveness of herbicide formula is
calculated by comparing the mortality rates of
weeds in plots treated AG and AC against weed
mortality in the control plots.
RESULTS AND DISCUSSION
Weed identification
In the first experiment at farmer’s field in
Ciapus, Bogor, various broad leaf weeds identified
were Ageratum conyzoides, Synedrella nodiflora,
Borreria alata, B. laevis, Phyllanthus niruri,
Euphorbia hirta, Mimosa Invisa, Erechtites
valerianifolia (Crassocephalum crepidioides), Sida
rhombifolia, Amaranthus dubious (spinach spines),
Diodia sarmentosa, and Galinsoga parviflora,
whereas narrow weeds were Digitaria ciliaris,
Imperata cylindrica, Eleusine indica, Axonopus
compressus, Cyperus rotundus and C. kyllingia. All
the weeds found the experimental plots, although
the most dominant was A. conyzoides and B.
alata, whereas P. niruri and E. Hirta were growing
unequal in the plots.
In the second experiment at the Cicurug
Experimental Station, Sukabumi, 17 weeds were
identified, but the most dominant were Agerotum
conyzoides, Borreria latifolia and Cynedrella
nodiflora (broad leaf weeds), and Digitaria ciliaris
(narrow leaf weeds), such as Cyperus rotundus.
First experiment
Weeds sprayed with the formula of acetic

Bul. Littro, Volume 25, Nomor 2, Desember 2014
140
acid (AC and AG treatment) instantly dried up like
burning leaves within 1-2 hours after the
treatment. Broad leaf weeds, such as B. alata, A.
conyzoides, S. nodiflora, P. niruri and E. hirta were
the most sensitive. According Tjokrowardojo and
Djauhariya (2011) those weeds (Ageratum
conyzoides, Synedrella nodiflora, Borreria alata,
Borreria laevis, Axonopus compressus, Cynodon
dactylon, Digitaria ciliaris, Eleusine indica, Cyperus
rotundus and Cyperus kyllingia were dominant in
ginger cultivating areas and caused a significant
yield reduction.
One day after the treatment, more
obvious burning symptoms were observed in all
plots. This suggests that this acetic acid base
herbicide acts as a contact poison. Similarly,
Abouziena et al. (2009) and Evans and Bellinder
(2009) found that 30% acetic acid and 10% citric
acid solutions were effective against broad leaf
weeds. However, the narrow leaf weeds such as
grass did not affect. Two weeks after the
application, all weeds were completely dried
(scores 3-4) in all treated plots. The higher the
concentration the more severe the symptoms
(Table 1). Effectiveness of the two formulas was
lasting from three weeks after the application. Its
effectiveness is equivalent to 2,4-D amine rate at
1.5 l ha-1.
Treatment formula AG (10 and 15%) which
contains acetic acid and salts, as well as air
conditioning formula that contains acetic acid +
citrate acid (10 and 15%) growth does not occur
again (regrowth) after one month of application;
means both treatment deadly weed perfectly.
However, on a plot that had been treated with the
second formula, three weeks after treatment
grow other types of weeds (Table 2). Percentage
weed cover just reached less than five percent in
the Accetic acit Citric acit (AC) and Aceatic acit
+solt NaCl (AG) treatment, and 2,4D, whereas in
the control treatment weeding manually (hand
weeding) percentage reaches 20-30%, meaning
that most of the experimental plot was overgrown
with weeds. The low percentage of weed cover,
although in the control treatment without treat-
ment, is also related to the weather conditions
are getting dry (dry season), where the growth of
new weeds getting smaller. This reflects that the
herbicide AC and AG are a growing herbicide post
(post-emergence) and contacts that are not
deadly weed seeds in the tillage layer.
Table 1. Severity of acetic acid and citric acid base formulas on target weeds, three weeks after treatment.
Tabel 1. Keparahan pada gulma target setelah aplikasi formula berbasis asam asetat dan asam citrat, tiga minggu
setelah aplikasi.
Treatment a)
Severity (%) b)
Borreria alata
Ageratum conyzoides
Synedrella nodiflora
Phyllanthus niruri
Euphorbia hirta
AG 10
3
3
3
4
4
AG15
3
4
4
4
4
AC10
3
4
3
4
4
AC15
4
3
4
4
4
2,4D 0,3
3
4
4
4
4
Control
0
0
0
0
0
Note: a) AG = acetic acid + NaCl; AC = acetic acid + citric acid; 2,4 D = 2, 4 dichloro phenoxy acetic acid.
b) Severity score: 0 = no effect or very low (0-5% toxicity), 4 = severe (75-100% toxicity).
Keterangan: a) AG= asam asetat + NaCl; AC= asam asetat + asam sitrat; 2,4D dichloro phenoxy acetic acid.
b) Nilai keparahan: 0=tidak ada efek atau rendah keracunannya (0-5% toksisitas), 4=sangat beracun (75-100%
keracunannya).

Sri Rahayuningsih and Supriadi : Herbicidal Efficacy of Acetic Acid and Citric Acid Base on Broad Leaf Weeds of Medicinal Crops Fields
141
Second experiment
The effect of spraying of herbicide
solutions on target weeds was presented in Table
3. The result showed the acetic acid base formula
(acetic acid + NaCl and acetic acid + citric acid)
applied at 15 and 20% was as effective as
synthetic herbicide 2,4 D sprayed at the
recommended dosage (0.3%). The combination of
the three substances, i.e. acetic acid + citric acid +
NaCl did not significantly differ from that of the
two combinations. The effect of wood vinegar in
the formula of VACG did not increase its
effectiveness, but the addition of wood vinegar is
important for reducing aroma of acetic acid.
Incorporating of NaCl in the formula may not be
necessary, because NaCl is not degradable in the
soil.
Weed recovery
The results showed that before
application, the land was mainly dominated with
broad leaves, such as Ageratum conyzoides,
Borreria latifoli and Cynedrela nodiflora. All the
acetic acid base formulas tested (AC, AG, ACG and
VACG) were toxic to broad leaf weeds shown as
leaf burn (score three out of four) one hour after
application. Six weeks following application, dry
weight of the weeds remained less than less than
five percent (none to few broad leaf weed
Table 2. Regrowth of weeds three weeks after treatment.
Table 2. Pertumbuhan kembali gulma tiga minggu setelah aplikasi.
Treatments a)
Weed coverage (%)b)
Borreria alata
Ageratum conyzoides
Synedrella nodiflora
Phyllanthus niruri
Euphorbia hirta
AG 10
5
5
5
5
5
AG15
5
5
5
5
5
AC10
5
5
5
5
5
AC15
5
5
5
5
5
2,4D (0.3)
5
5
5
5
5
Control
30
35
20
10
5
Note: a) AG = acetic acid+ NaCl; AC = acetic acid + citric acid; 2,4 D = 2, 4 dichloro phenoxy acetic acid.
b) Severity score: 0 = no effect or very low (0-5 % toxicity), 4 = severe (75-100 % toxicity).
Keterangan: . a) AG= asam asetat + NaCl; AC= asam asetat + asam sitrat; 2,4D dichloro phenoxy acetic acid.
b) Nilai keparahan: 0=tidak ada efek atau rendah keracunannya (0-5% toksisitas), 4=sangat beracun (75-100% keracunannya)
Table 3. Severity of acetic acid base herbicide formulas on several weeds grown in the Cicurug Experimental Station.
Table 3. Keparahan pada beberapa jenis gulma setelah aplikasi formula berbasis asam asetat dan asam citrat, tiga
minggu setelah aplikasi.
Treatment a)
Severity scores of 0-4 scales (%)
Ageratum
conyzoides
Borreria
latifolia
Cynedrela
nodiflora
Cleome
aspera
Amaranthus sp
Mimosa
invisa
Mimosa
pudica
AC (15)
4
3
4
4
3
3
3
AC (20)
4
3
4
4
3
3
3
AG (15)
4
3
4
4
4
3
3
AG (20)
4
4
4
4
3
4
3
ACG (15)
4
4
4
4
4
3
3
ACG (20)
4
4
4
4
4
4
3
VACG (15)
4
4
4
4
4
4
4
VACG (20)
4
4
4
4
4
4
4
2.4-D (0.3)
4
4
4
4
4
4
4
Control
0
0
0
0
0
0
0
Note: a) AC = acetic acid + citric acid; AG = acetic acid + NaCl; ACG = acetic acid + citric acid+NaCl; VACG = wood vinegar + acetic acid
+ citric acid + NaCl.
b) Severity score: 0-5 scales; 0 = 0-5 % toxicity, 4 = 75-100% toxicity.
Keterangan: a) AG= asam asetat + NaCl; AC= asam asetat + asam sitrat; 2,4D dichloro phenoxy acetic acid.
b) Nilai keparahan: 0=tidak ada efek atau rendah keracunannya (0-5% toksisitas), 4=sangat beracun (75-100%
keracunannya).

Bul. Littro, Volume 25, Nomor 2, Desember 2014
142
regrowth on plot experiments) compared with the
standard herbicide treatment (Figure 1). However,
there was a shift domination of grass weeds on
the plots. Acetic acid content in the formulas
ranged from 1-30%, depending on the formulas.
Note/Keterangan: AC = acetic acid+ citric acid; AG = acetic
acid + NaCl; ACG = acetic acid + citric +
NaCl; VACG = wood vinegar + acetic acid +
citric + NaCl.
Figure 1. Weed dry weight on experimental plots
treated with acetic acid and citric base
formula in the Cicurug Experimental Station.
Gambar 1. Berat kering gulma pada plot percobaan
yang diperlakukan dengan formula berbasis
asam asetat dan asam sitrat di KP. Cicurug.
The results showed that the herbicide
formula contains a mixture of acetic acid and
acetic acid + NaCl + citric acid potential as
herbicides, especially for the types of broadleaf
weeds, such as B. alata, A. conyzoides, S.
nodiflora, P. niruri and E. hirta. However, the main
constraint is the amount of concentration that is
still too much (10-15%) making it less able to
compete with existing commercial formulas that
use the average concentration of 0.5-1%. To
reduce the magnitude of the effective
concentration of the herbicide formula AG or AC it
is necessary to study the effect of a mixture of
formula herbicide AG or AC with herbicide other
active ingredients. Acenas et al. (2013) showed
that a mixture of liquid smoke (pyroligneous acids)
containing the main compound with acetic acid
herbicide butyl bentazone + cyhalof more
effective to control broad leaf weeds. The main
drawback of the formula mixture of acetic acid
and acetic acid + NaCl + citric acid is a very
pungent odour. To that end, the improvement of
the formula needs to be done to reduce the
odour, such as by incorporating liquid smoke in
the formulation. Liquid smoke can neutralize the
scent, (Rico et al., 2007; Evans and Bellinder 2009)
it can be used as a solvent in the formula
herbicide mixtures containing oil of cloves and
active ingredients of other herbicides. These
herbicides can be applied to the cultivation of
medicinal plants of the family of the gramineae.
CONCLUSION
An acetic acid base formula containing
acetic acid, NaCl, citric acid and wood vinegar
applied at 10-15% were effective in controlling
broadleaf weeds on medicinal crops’s land such as
B.alata, A. conyzoides, S. nodiflora, P. niruri and E.
hirta. Mechanism of action of the herbicide
formula is a with contact poison. The most
promising formula is acetic acid + citric acid +
wood vinegar. However, the formula did not
affect grasses.
ACKNOWLEDGEMENTS
The authors would like to thank Ir. Agus
Sudiman, MS and Drs. Endjo Djauhariya for all
their help in carrying out this study. This work was
financially supported by the Incentive Research
Program the ministry of Research and Technology
Republic of Indonesia in 2011-2012.
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