This study evaluated the herbicidal efficacy of aqueous extracts from different parts of Chromolaena odorata

(L.) enhanced with coconut vinegar for the control of common weeds under field conditions. Specifically, the

study aimed to determine which plant part (leaves, roots, or stems) exhibited the greatest weed control efficacy

compared with a positive control (sterile distilled water) and a negative control (glyphosate). The experiment

was conducted using a Randomized Complete Block Design (RCBD) with five treatments and three replications.

The treatments consisted of T1 – Sterile Distilled Water (positive control), T2 – C. odorata leaves + coconut

vinegar + sterile distilled water, T3 – C. odorata roots + coconut vinegar + sterile distilled water, T4 – C. odorata

stems + coconut vinegar + sterile distilled water, and T5 – Glyphosate (negative control). Results showed that

the C. odorata-based formulations significantly suppressed weed growth compared with the untreated control.

0.001). Tukey's Honestly Significant Difference (HSD) test indicated that all C. odorata-based treatments

significantly outperformed the untreated control, while no significant differences were observed among the leaf,

root, and stem extracts. However, glyphosate provided significantly greater weed control than the botanical

formulations after 14 days. Among the weed species evaluated, Cleome rutidosperma was the most susceptible

to the C. odorata extracts, whereas Physalis angulata was the least affected. The findings demonstrate that

aqueous extracts of C. odorata enhanced with coconut vinegar possess promising herbicidal activity and can

effectively suppress common weeds, particularly during the early stages of weed growth. Although their efficacy

was lower than that of glyphosate over time, the comparable performance of the leaf, root, and stem extracts

suggests that allelopathic compounds are distributed throughout the plant. These results highlight the potential

of C. odorata as a sustainable botanical herbicide and provide a basis for further optimization of formulation,

interfere with irrigation and harvesting operations, reduce crop quality, and contaminate harvested produce with

weed seeds. Consequently, uncontrolled weed infestations can cause substantial yield losses and increased

production costs. Weed management commonly relies on tillage, hand weeding, and synthetic herbicides.

Although synthetic herbicides provide rapid and effective weed control, their prolonged and indiscriminate use

has raised concerns regarding environmental pollution, herbicide resistance, and adverse effects on soil health

and biodiversity. Herbicides may alter soil microbial communities, affect nutrient cycling, contaminate water

resources, and negatively impact non-target organisms (Haney et al., 2000; Johnsen et al., 2001; Duke & Powles,

2008).

These concerns have intensified the search for environmentally friendly alternatives, particularly plant-based

leaching, or decomposition of plant residues and can inhibit seed germination, root elongation, photosynthesis,

nutrient uptake, and other physiological processes essential for plant growth (Inderjit & Duke, 2003; Cheng &

Cheng, 2015).

One plant with considerable potential as a source of natural herbicides is Chromolaena odorata (L.) R.M. King

& H. Robinson, commonly known as Siam weed or hagonoy. Native to tropical America, it has become one of

the world's most invasive weeds due to its rapid growth, high adaptability, and strong allelopathic activity

(Zachariades et al., 2009). The species suppresses surrounding vegetation not only through competition for

resources but also through the release of phytotoxic secondary metabolites. Phytochemical studies have

identified numerous bioactive compounds in C. odorata, including phenolic acids such as gallic, caffeic,

chlorogenic, ferulic, and p-coumaric acids; flavonoids including quercetin, kaempferol, rutin, and luteolin; as

1980). Aqueous extracts of C. odorata have demonstrated inhibitory effects on the germination and seedling

growth of several crop and weed species, suggesting their potential as an environmentally friendly weed

management tool. Furthermore, combining these extracts with coconut vinegar, which contains acetic acid

capable of rapidly damaging plant tissues, may enhance herbicidal efficacy through complementary modes of

action (Webber et al., 2005).

Considering the abundance of C. odorata, its rich composition of allelopathic compounds, and the increasing

demand for sustainable weed management strategies, this study was conducted to evaluate the herbicidal

potential of aqueous extracts from the leaves, stems, and roots of C. odorata, both alone and in combination with

coconut vinegar, as a potential organic herbicide.

material mixed with 3 L of sterile distilled water, corresponding to a 1:3 (w/v) extraction ratio (approximately

stand for 72 hours at room temperature (27–30°C) under shaded conditions without direct sunlight. The

containers were gently stirred twice daily to facilitate the extraction of water-soluble allelochemicals. After 72

hours, the extracts were filtered through a fine mesh cloth to remove plant residues and obtain the crude aqueous

extracts.

Commercially available naturally fermented coconut vinegar (5% acidity) was used as an enhancer in the

formulation. Coconut vinegar was incorporated based on its reported ability to lower the pH of the extract,

The experiment was laid out using a Randomized Complete Block Design (RCBD) with five treatments and

three replications. The treatments were as follows:

 For Treatments 2–4, the final formulation consisted of T1 – Positive Control (Sterile Distilled Water)

 T2 – Chromolaena odorata leaves + Coconut Vinegar + Sterile Distilled Water

 T3 – Chromolaena odorata roots + Coconut Vinegar + Sterile Distilled Water

 T4 – Chromolaena odorata stems + Coconut Vinegar + Sterile Distilled Water

The field experiment was conducted under natural environmental conditions during the cropping season.

Throughout the experimental period, the site experienced typical tropical climatic conditions, with ambient

temperatures ranging from approximately 28–33°C, relative humidity of 75–90%, and intermittent rainfall. No

rainfall occurred immediately after treatment application; however, rainfall was observed approximately three

days after spraying, minimizing the likelihood of immediate wash-off of the treatments. Environmental

conditions were monitored throughout the study to ensure that treatment responses reflected normal field

conditions.

The experimental area was divided into plots measuring 1 × 1 m per replication, with 0.5 m alleys between plots.

Weed species present in the field were identified, with the dominant species including Cleome rutidosperma,

Figure 1. The common weeds. A. Cleome rutidosperma B. Physalis angulata, C. Echinocloa colona, D.

Heliotropium indicum

Evaluation for weed control was conducted to the identified dominant weeds species in the area and was based

on the percentage weed control using the ratings below.

Table 1. Weed control rating method described in Lanie et al. (1993), Lanie et al. (1994), Murray et al. (1994),

Although the C. odorata-based formulations demonstrated promising herbicidal activity, their effectiveness

remained numerically lower than glyphosate. Rainfall occurring three days after application may have reduced

the persistence of the extracts on the leaf surface through wash-off, thereby limiting absorption of the active

compounds. Moreover, because aqueous C. odorata extracts function primarily as contact herbicides, they are

unlikely to reach protected meristematic tissues or underground plant structures, allowing some weeds to survive

recommended to improve efficacy and support the development of C. odorata-based bioherbicides for

sustainable weed management.

Although glyphosate achieved complete weed control after fourteen days, the C. odorata-based formulations

still demonstrated appreciable herbicidal activity, highlighting their potential as environmentally friendly

alternatives for integrated weed management. Their efficacy may be further improved through optimization of

extract concentration, refinement of extraction procedures, repeated application schedules, incorporation of

natural surfactants or sticking agents to enhance leaf retention and penetration, or combination with other plant-

management.

Figure 3. Common effects of the different treatments after 14 days of application. A. Cleome rutidosperma

started to regrowth B. scorched leaves of young Heliotropium indicum C. No injury on Physalis angulata D.

completely controlled weeds in treatment 5

days of application.

thereby allowing regrowth from surviving meristematic tissues in some weed species.

Based on the findings of this study, the following recommendations are proposed; The C. odorata-based

formulations should be applied during dry, sunny weather, preferably in the afternoon, to maximize their

effectiveness as contact herbicides and minimize losses due to rainfall or wash-off.

or sticking agents, as well as combinations with other plant-derived herbicides, to enhance leaf retention,

penetration, persistence, and overall herbicidal efficacy under field conditions. Additional field trials should be

conducted across different agroecological conditions, seasons, cropping systems, and a broader range of weed

species to determine the consistency and general applicability of the botanical formulations under varying

environmental conditions. Long-term studies should assess the environmental safety of C. odorata-based

herbicides, including their persistence in soil, effects on soil microbial communities, beneficial insects, non-

target plants, aquatic organisms, and overall ecosystem health.

Future research should also evaluate the economic feasibility, cost-effectiveness, and practical applicability of

producing and using C. odorata-based herbicides, particularly for smallholder farmers, including analyses of

production costs, labor requirements, availability of raw materials, and potential adoption compared with