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    Plant extract-based nanoemulsion for controlling sweet potato pests and weeds
    (2026-12-01)
    Pumnuan, Jarongsak
    ;
    Ruddit, Anusart
    ;
    Lakyat, Anuwat
    ;
    Doungnapa, Thanaporn
    ;
    Deemak, Jantra
    The sweet potato weevil (Cylas formicarius) is the most destructive pest of sweet potato and is often associated with diseases and weeds. The use of plant extracts as pest control agents is a promising, eco-friendly approach, but their effectiveness often declines under field conditions. Therefore, nanoemulsion technology was applied to improve the dispersion and bioefficacy of active compounds. In this study, we aimed to develop plant extract-based nanoemulsions as multifunctional biopesticides capable of controlling insect pests, fungal pathogens, and weeds. Twenty-one plant extracts were screened for their effects adult SPW via contact methods. The most potent extracts were then formulated into nanoemulsions and evaluated for insecticidal efficacy—including contact toxicity, repellency, and oviposition inhibition. In addition to insecticidal effects, antifungal and herbicidal activities were systematically assessed against Fusarium sp. and two common weed species in sweet potato fields, Amaranthus tricolor and Echinochloa crus-galli. The major chemical constituents of key extracts were identified using gas chromatography–mass spectrometry (GC–MS). Among all extracts, the hexane extracts of star anise and long pepper exhibited the highest contact toxicity, with LC50 values ranging from 2.051 to 2.415% at 24 h. When formulated into nanoemulsions (NHEF-1 and NHEH-2), toxicity increased 16- to 18-fold, lowering LC<inf>50</inf> values to 0.114–0.150%, and at above 0.1%, oviposition was inhibited by more than 85%. Both formulations also demonstrated significant antifungal activity against Fusarium sp. (44.6–56.8% growth inhibition) and completely inhibited the germination of A. tricolor (at 0.01%) and E. crus-galli (at 1.0%). GC–MS analysis revealed anethole (84.49%) as the predominant compound in the star anise extract, with long pepper extract containing moderate amounts of several compounds. These findings demonstrate the potential of plant extract-based nanoemulsions as eco-friendly, multifunctional biopesticides for sustainable sweet potato management, integrating enhanced insecticidal, antifungal, and herbicidal effects.
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    Item type:Publication,
    Effects of natural herbicide from tagetes erecta on echinochloa crus-galli (L.) beauv
    (2018-01-01)
    Wichittrakarn, P.
    ;
    Teerarak, M.
    ;
    Charoenying, P.
    ;
    Laosinwattana, C.
    We studied the inhibitory effects of leaves extracts of Tagetes erecta on weed-seed germination and the mechanisms involved. Hydroethanolic crude extract (OR) from Tagetes erecta dried leaves was partitioned into four fractions: hydrolyzed (HY), aqueous (AQ), neutral (NE) and acidic (AE). The inhibitory effects of crude extracts and its fractions were evaluated on germination and seedlings growth of Echinochloa crus-galli (L.) Beauv. The total phenolic and flavonoid contents of each fraction were also determined. Germination and seedling growth were drastically inhibited by HY and AE followed by NE, OR and AQ. The HY and AE fractions had higher concentrations of both phenolics and flavonoids than other fractions. The HY fraction was selected as most potent for development as natural herbicide due to its high yield and strong inhibitory effects. The HY fraction was formulated into a soluble concentrate product (SCT) and its inhibition potential and modes of action were investigated. The SCT drastically inhibited the seed germination of E. crus-galli, inhibiting both imbibition, α-amylase activity and also seedling growth. Cytogenetic bioassays of SCT on root-tip cells of Allium cepa L. showed that it inhibited the mitosis and thereby the cell division. It is likely that a natural herbicide may be developed from the hydrolyzed fraction of a hydroethanolic extract of Mexican marigold leaves.
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    Item type:Publication,
    Phytotoxic effects of essential oil from Cymbopogon citratus and its physiological mechanisms on barnyardgrass (Echinochloa crus-galli)
    (2013-01-01)
    Poonpaiboonpipat, Tanatson
    ;
    Pangnakorn, Udomporn
    ;
    Suvunnamek, Umporn
    ;
    Teerarak, Montinee
    ;
    Charoenying, Patchanee
    Lemongrass (Cymbopogon citratus) essential oil was identified by GC-MS for their major compound constituents; six compounds representing 92.59% of the total essential oil were identified. The main constituent was citral (76.00%). In a laboratory bioassay, high concentration of essential oil significantly inhibited germination and seedling growth of Echinochloa crus-galli and affecting α-amylase activity of seeds. In a glass house bioassay, essential oil at concentrations of 1.25, 2.5, 5 and 10% (v/v) was foliar-applied on E. crus-galli at 28 days after sowing at spray volume of 1000Lha <sup>-1</sup>. Observation of leaf wilt symptoms was noted at 6h after treatment. Chlorophyll a, b and carotenoid content was decreased with concentrations of essential oil, indicating that essential oil interferes with photosynthetic metabolism. C. citratus essential oil caused an electrolyte leakage indicating membrane disruption and loss of integrity. Treated leaves exhibited an increase in thiobarbituric acid reactive substances (TBARS), suggesting lipid peroxidation. It is to conclude that essential oil is phytotoxic and could be utilized as a natural herbicide for future weed control. © 2012 Elsevier B.V.
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    Allelopathic potential of Chinese rice flower (aglaia odorata Lour.) as organic herbicide
    (2009-01-01)
    Laosinwattana, C.
    ;
    Poonpaiboonpipat, T.
    ;
    Teerarak, M.
    ;
    Phuwiwat, W.
    ;
    Mongkolaussavaratana, T.
    The aqueous extracts of leaf and branches of Aglaia odorata inhibited the germination and seedling growth of bamyardgrass (Echinochloa crus-galli (L.) Beauv.) and wild pea (Phaseolus lathyroides L.) over the control. Besides its dry leaf powder (31.25, 62.5, 125 and 250 mg/plate) was more inhibitory to these parameters than aqueous extract. Furthermore, the inhibitory effects of dried leaf pellets of Chinese rice flower were more stronger than dried leaf powders at equal rates. The pellets applied at 0.5 ton ha<sup>-1</sup> dose as soil surface mulch inhibited the seedlings emrgence of banyardgrass and wild pea by 67% and 2%, respectively. Thus the Chinese rice flower pellets has the potential to act as organic herbicide for control of bamyardgrass weed.