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Sensitivity of Phytophthora palmivora Causing Durian Diseases to Metalaxyl-M and Dimethomorph in Southern and Eastern Thailand
(2025-05-14)
Kongtragoul, Pornprapa
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Charoensiri, Sasidara
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Rimchon, Somkiat
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Knight, Susan
Metalaxyl-M (Met-M) and dimethomorph (Dim) are two systemic fungicides commonly used in Thailand to treat durian rot diseases caused by Phytophthora palmivora, a pathogen that significantly affects durian production. Fungicides have long been used by Thai durian farmers to control this infection, but managing the disease has become increasingly challenging in recent years. Monitoring fungicide resistance evolution is essential for effective disease management. In 2020 and 2022, eighty-one and sixty isolates, respectively, were collected from naturally infected durians in southern and eastern Thailand. All isolates were identified as P. palmivora through sporangium formation. Furthermore, 23 out of the 141 isolates were confirmed as P. palmivora based on sequencing of the internal transcribed spacer (ITS) and 5.8S regions of rDNA. All isolates were tested for mycelium growth sensitivity to Met-M and Dim. EC50 values were used to classify sensitivity into three categories: sensitive (S) at EC50 < 1 mgL-1, moderately resistant (MR) at EC50 between 1 and 100 mgL-1, and resistant (R) at EC50 > 100 mgL-1. In southern Thailand, 58% of the isolates were Met-MRDimS, and 41.25% were Met-MSDimS. In eastern Thailand, 36.67% were Met-MMRDimS, and 41.67% were Met-MSDimS. These findings indicate that the populations of P. palmivora in the durian orchards in southern and eastern Thailand consisted of a mixture of sensitive, moderately resistant, and resistant strains.
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Enhanced biodiesel purification using coffee husk bioadsorbents: The role of pyrolysis temperature, KOH activation, and adsorption efficiency
(2025-05-01)
Chungcharoen, Thatchapol
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Limmun, Warunee
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Srisang, Siriwan
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Phetpan, Kittisak
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Ruttanadech, Nuttapong
This study evaluates the performance of bioadsorbents derived from coffee husk pyrolyzed at temperatures of 600, 700, and 800 °C (CH600, CH700, and CH800), along with activated CH700 (ACH700), in biodiesel purification. The results indicate that CH700 significantly enhances biodiesel purity, with optimal purification conditions achieved at a dosage of 2 wt% CH700, a stirring rate of 400 rpm, and a contact time of 45 min. CH700 demonstrated modest performance, achieving approximately 20 % removal of methanol and water. However, after activation with potassium hydroxide (KOH), ACH700 demonstrated improved efficiency, achieving 96.92 % methanol removal and 39.46 % water removal. ACH700 also refined biodiesel quality to meet EN14214 standards and maintained a higher biodiesel yield compared to other adsorbents. The bioadsorption process is influenced by the chemical interactions between the surface functional groups of the bioadsorbent and the contaminants, which is further enhanced by the optimized pore structure of ACH700. The use of ACH700 represents a novel and highly effective approach to biodiesel purification, combining both technical efficiency and economic feasibility. Furthermore, the valorization of agricultural waste adds significant environmental benefits, reinforcing the potential of ACH700 for large-scale biodiesel production.
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Low-Cost Activated Carbon for Methylene Blue Adsorption Using Inert Gas-Free Carbonization and Microwave Activation
(2025-01-01)
Kongtragoul, Pornprapa
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Keeratirawee, Kanchalar
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Choola-Aied, Orasa
-This study investigated the preparation of activated carbon from spent coffee grounds for methylene blue adsorption using inert gas-free carbonization and microwave activation. Spent coffee grounds were obtained from a local coffee shop in Pathio, Chumphon, Thailand. The coffee grounds were pretreated with 1M H<inf>2</inf>SO<inf>4</inf> before undergoing carbonization at 600 ºC for 3 h in a limited-oxygen atmosphere. The obtained carbon materials were chemically activated with zinc chloride (ZnCl<inf>2</inf>) and physically activated using a microwave-assisted method at 300 W for 180 seconds. The adsorption of methylene blue was evaluated using a batch method. Methylene blue adsorption contact time, effect of pH, and initial concentration were investigated. The maximum adsorption capacity of the activated carbon for methylene blue removal was found to be 29.24 mg/g. The prepared activated carbon exhibited a BET surface area of 70.08 m2/g and reached equilibrium in 120 min at the optimum pH of 9. The adsorption isotherm was consistent with the Freundlich model, while the adsorption kinetics followed a pseudo-second-order model. The findings indicate that activated carbon is a cost-effective and efficient adsorbent for methylene blue removal from aqueous solutions.
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Preparation of Low-Cost Activated Carbon from Spent Coffee Grounds for Rhodamine B Removal
(2025-01-01)
Keeratirawee, Kanchalar
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Choola-aied, Orasa
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Kongtragoul, Pornprapa
A low-cost coffee-based activated carbon for Rhodamine B (RhB) removal was investigated. Spent coffee grounds obtained from a local coffee shop in Pathio, Chumphon, Thailand, were utilized as the raw material to produce biochar. The coffee grounds were pre-treated by washing with 1M H2SO4 before carbonization at 600 ºC for 2 h under a limit-oxygen atmosphere. The acid washing process was found to be a promising method for preparing activated carbon without requiring an inert gas flow during the carbonization. This approach resulted in activated carbon free of ash after carbonization. The carbonized coffee grounds were activated using a microwave-assisted process with KOH as the activating agent. The performance of the prepared activated carbon for Rhodamine B adsorption was evaluated using the batch method. Key parameters, including initial concentration of Rhodamine B (3-11 mg/L), pH (3-11), and contact time (15-150 min), were optimized. The maximum adsorption capacity was 16 mg/g of adsorbents. The optimal pH for Rhodamine B adsorption was found to be 7. The adsorption of Rhodamine B onto the adsorbent fits a Langmuir isotherm and a pseudo-second-order kinetic model. The study revealed that the prepared activated carbon from waste coffee grounds is an efficient and affordable solution for removing Rhodamine B contaminants from the water system.
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Antifungal copper nanocomposite-rubber compound for tree wound dressings
(2024-12-15)
Noppradit, Benjaporn
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Uthaipan, Nattapon
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Klinnawee, Lompong
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Kongtragoul, Pornprapa
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Phengdaam, Apichat
This study combines copper nanoparticles (CuNPs) with a rubber compound to develop a tree wound dressing that reduces tree mortality from infections, utilizing broad-spectrum antifungal and adhesive properties of composite material. Phytotoxicities of CuNPs with an average size of 6 nm were significantly lower than those of Cu ions, evaluated by the germination index using lettuce seeds and membrane integrity index using stems of rubber seedling. After that, the synthesized CuNPs were then loaded into a natural rubber (NR) latex compound at concentrations ranging from 0 to 90 mg/L to produce a CuNP composite adhesive. The shear strength, representing adhesion on wood, was evaluated using lap shear testing, revealing a 50 % reduction in maximum force at the highest CuNP loading. This loss of shear strength was attributed to interference by copper ions in the vulcanization of the NR latex compound, as indicated by FT-IR spectroscopy. After that, the CuNP composite adhesive was formed into a film to test antifungal properties against Colletotrichum spp. Based on the in vitro plate inhibition zone assay, 10 mg/L of CuNPs inhibited the growth of Colletotrichum spp. The size of inhibited zone was significantly increased by 150 and 300 % when concentrations of CuNPs were 70 and 90 mg/L, respectively. This research provides the first evidence of the low phytotoxicity of CuNPs compared to copper ions at equivalent concentrations and demonstrates the efficacy of CuNP composites with NR compounds as tree wound dressings.
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EFFECT OF ZINC OXIDE NANOPARTICLES AGAINST PHYTOPHTHORA SPP. CAUSING DURIAN DISEASES IN VITRO
(2024-01-01)
Keeratirawee, Kanchalar
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Kongtragoul, Pornprapa
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Pantakan, Sansanee
The efficiency of zinc oxide nanoparticles (ZnO-NPs) in inhibiting Phytophthora spp. growth in both durian fruits and stems is demonstrated. The size of ZnO-NPs used was in range of 25-50 nm in diameter. Diseased durian sample were collected from a durian orchard located in southern of Thailand. The pathogen of diseased durian was isolated for subsequent morphological identification. Three distinct strains of Phytophthora spp. (designated as PHY41, PHY45, PHY49) were successfully isolated and were found in colonies with rings and stellate pattern, ovoid, limoniform sporangium with semi-papillate or papillate, and formation chlamydospores. All isolates were exhibiting 100% pathogenicity on durian, as indicated by the disease incidence (DI). The concentration of ZnO-NPs played a crucial role in suppressing the growth of Phytophthora spp. in all isolates. Higher concentration of ZnO-NPs resulted in increased inhibition of growth. ZnO-NPs at the concentration of 2000 µg/mL effectively suppressed the mycelial growth of all fungi isolates at 57.76-69.84%. Additionally, ZnO-NPs at the concentration of 500 µg/mL completely inhibited the sporulation only in the PHY49 strains. Furthermore, ZnO-NPs concentration ranging from 1000-2000 µg/mL resulted in completed inhibition in sporulation in all Phytophthora spp. isolates. The result demonstrated that ZnO-NPs at all concentrations effectively delayed the germination of Phytophthora spp.
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ZINC OXIDE NANOPARTICLES INHIBIT SOME FUNGAL PATHOGENS INFECTION ON DURIAN SEEDLINGS
(2024-01-01)
Kongtragoul, Pornprapa
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Pantakan, Miss Sansanee
Durian disease-causing organisms such as fungi can infect durian trees at any stage of development. Chemical fungicides are widely used because they are convenient and simple to use. However, it impacts the health of producers, consumers, and the environment. As a result, recommendations have been developed and established for researching zinc oxide nanoparticles (Zn-ONPs) that can inhibit fungal growth as an alternative for preventing and eliminating such fungi. The purpose of this study is to collect and isolate some fungi that cause durian diseases and their pathogenicity test, as well as to investigate the efficacy of Zn-ONPs ranging in size from 25 to 50 nm in inhibiting germination and fungal infection on durian seedlings. Three isolates of Phytophthora sp. (CL4_F1, CL4_S5, CL4_F10), two isolates of Fusarium sp. (CL6_FL1, CL6_FL2), two isolates of Phomopsis sp. (CH1_PF1, CH1_PF2), and two isolates of Rhizoctonia sp. (CL1_RL1, CL1_RL2) were successfully isolated as durian pathogenic fungi. All isolates were pathogenic on durian seedlings, with a 100% disease incidence. As a result, it was found that increasing the concentration of ZnO-NPs could further inhibit growth in the germination and infection of durian seedlings. All tested isolates had delayed germination by ZnO-NPs at all concentrations. Furthermore, as the severity of the disease decreased, ZnO-NPs could inhibit infection in durian seedlings at higher concentrations.
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Isolates of Colletotrichum truncatum with Resistance to Multiple Fungicides from Soybean in Northern Thailand
(2023-09-01)
Poti, Teeranai
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Thitla, Tanapol
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Imaiam, Naphatsawan
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Arunothayanan, Hatthaya
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Doungsa-Ard, Chanintorn
In Thailand, four systemic fungicides-carbendazim (Car), azoxystrobin (Azo), difenoconazole (Dif), and penthiopyrad (Pen)-are commonly used to control soybean anthracnose caused by Colletotrichum truncatum; however, the pathogen has developed resistance. From 2019 to 2020, fungicide resistance in C. truncatum from fields in Chiang Rai and Chiang Mai was monitored. In tests of 85 C. truncatum isolates for resistance to multiple fungicides, 15.3% were CarRAzoR, 34.1% were triple resistant (CarRAzoRDifR or CarRAzoRPenR), and 50.6% were CarRAzoRDifRPenR. Surprisingly, all isolates tested had lost their sensitivity to one or more of the fungicides tested. The carbendazim-resistant isolates carried a point mutation in the b-tubulin gene at codon 198 (E198A) or 200 (F200Y), and all azoxystrobin-resistant isolates had a mutation in the cytochrome b gene at codon 143 (G143A) or 129 (F129L). Moreover, a novel mutation at codon 208 (S208Y) in the gene encoding succinate dehydrogenase subunit B was detected in all of the isolates highly resistant to penthiopyrad. No mutation linked with difenoconazole resistance was detected in the genes encoding cytochrome P450 sterol 14a-demethylase. To the best of our knowledge, this is the first report of C. truncatum isolates resistant to multiple fungicides and serves as a warning to take measures to prevent the occurrence and distribution of these multiple-fungicide-resistant populations in soybean fields.
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Research Article Biosynthesis of Silver Nanoparticles Using Garcinia cowa Aqueous Leaf Extract and Their Antifungal Activity Against Durian Dieback Pathogen
(2023-09-01)
Sukkha, Usa
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Khejonrak, Awadol
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Kamonpha, Phitsamai
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Ruangvittayanon, Anuchit
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Pakdeepromma, Sirichatnach
Silver nanoparticles (AgNPs) were synthesized under different pH and reaction time using the Garcinia cowa aqueous leaf extract. The formation, crystal structure and morphology of synthesized AgNPs were investigated using UV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The UV-Vis result indicated that the AgNPs were synthesized using Garcinia cowa aqueous leaf extract at all pH conditions within 10 min. The synthesis of AgNPs was significantly affected by pH condition which was shown by the TEM micrographs. The particle sizes of AgNPs were in a nano-sized range; 6.30 ± 3.52 nm for pH 4, 3.87 ± 2.51 nm for pH 7 and 13.97 ± 11.84 nm for pH 10. Furthermore, the AgNPs prepared in pH 4, pH 7 and pH 10 (120 min reaction time) at different concentrations were assessed for their antifungal activity against durian dieback pathogen. It was found that the 800 mL/L of AgNPs prepared at pH 7, the smallest particle size and good dispersion, showed the highest inhibition mycelial growth at 47.33%, whereas the larger nanoparticles prepared at pH 4 and pH 10 conditions showed lower inhibition of mycelial growth at 43.22% and 32.55%, respectively.
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Rapid and accurate classification of Aspergillus ochraceous contamination in Robusta green coffee bean through near-infrared spectral analysis using machine learning
(2023-03-01)
Ruttanadech, Nuttapong
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Phetpan, Kittisak
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Srisang, Naruebodee
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Srisang, Siriwan
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Chungcharoen, Thatchapol
Near-infrared (NIR) spectral-based classification of Aspergillus ochraceous contamination in the Robusta green coffee bean was investigated. Six different learning algorithms, including linear discriminant analysis (LDA), support vector machine (SVM), k-nearest neighbors (KNN), decision tree (Tree), Naive Bayes (NB), and quadratic discriminant analysis (QDA), were applied for the investigating purpose. Four classes of fungal contamination on coffee beans, non-fungal contaminated beans on day 1 and day 3 (NCB-D1 and NCB-D3) and fungal contaminated beans on day 1 and day 3 (CB-D1 and CB-D3), were set for the classification intention. Based on the 6 learning algorithms, the Tree approach was optimal, displaying a training accuracy of 97.5%. As proven by the testing dataset, the classification accuracy of the Tree was also at 97.5%. With this number, the Tree could correctly classify 100% between the contaminated and non-contaminated coffee beans. These findings exhibit the potential of the NIR spectroscopy accompanied by machine learning for the early detection of fungal contamination in green coffee beans.

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