The residual levels and persistence of thiram in the soil, water and oil palm seedling leaves were investigated under field conditions. The experimental plots were carried out on a clay loam soil and applied with three treatments namely; manufacturer's recommended dosage (25.6 g a.i. plot-1), manufacturer's double recommended dosage (51.2 g a.i. plot-1), and control (water) were applied. Thiram residues were detected in the soil from day 0 to day 3 in the range of 0.22-27.04 mg kg-1. Low concentrations of thiram were observed in the water and leave samples in the range of 0.27-2.52 mg L-1 and 1.34-12.28 mg kg-1, respectively. Results have shown that thiram has a rapid degradation and has less persistence due to climatic factors. These findings suggest that thiram is safe when applied at manufacturer's recommended dosage on oil palm seedlings due to low residual levels observed in soil and water bodies.
Hexaconazole is a potential fungicide to be used in the oil palm plantation for controlling the basal stem root (BSR) disease caused by Ganoderma boninense. Therefore, the dissipation rate of hexaconazole in an oil palm agroecosystem under field conditions was studied. Two experimental plots were treated with hexaconazole at the recommended dosage of 4.5 g a.i. palm(-1) (active ingredient) and at double the recommended dosage (9.0 g a.i. palm(-1)), whilst one plot was untreated as control. The residue of hexaconazole was detected in soil samples in the range of 2.74 to 0.78 and 7.13 to 1.66 mg kg(-1) at the recommended and double recommended dosage plots, respectively. An initial relatively rapid dissipation rate of hexaconazole residues occurred but reduced with time. The dissipation of hexaconazole in soil was described using first-order kinetics with the value of coefficient regression (r (2) > 0.8). The results indicated that hexaconazole has moderate persistence in the soil and the half-life was found to be 69.3 and 86.6 days in the recommended and double recommended dosage plot, respectively. The results obtained highlight that downward movement of hexaconazole was led by preferential flow as shown in image analysis. It can be concluded that varying soil conditions, environmental factors, and pesticide chemical properties of hexaconazole has a significant impact on dissipation of hexaconazole in soil under humid conditions.
Exploiting plant extracts to form metallic nanoparticles has been becoming the promising alternative routes of chemical and physical methods owing to environmentally friendly and abundantly renewable resources. In this study, Momordica charantia and Psidium guajava leaf extract (MC.broth and PG.broth) are exploited to fabricate two kinds of biogenic silver nanoparticles (MC.AgNPs and PG.AgNPs). Phytoconstituent screening is performed to identify the categories of natural compounds in MC.broth and PG.broth. Both extracts contain wealthy polyphenols which play a role of reducing agent to turn silver (I) ions into silver nuclei. Trace alkaloids, rich saponins and other oxygen-containing compounds creating the organic corona surrounding nanoparticles act as stabilizing agents. MC.AgNPs and PG.AgNPs are characterized by UV-vis and FTIR spectrophotometry, EDS and TEM techniques. FTIR spectra indicate the presence of O-H, C = O, C-O-C and C = C groups on the surface of silver nanoparticles which is corresponded with three elements of C, O and Ag found in EDS analysis. TEM micrographs show the spherical morphology of MC.AgNPs and PG.AgNPs. MC.AgNPs were 17.0 nm distributed in narrow range of 5-29 nm, while the average size of PG.AgNPs were 25.7 nm in the range of 5-53 nm. Further, MC.AgNPs and PG.AgNPs exhibit their effectively inhibitory ability against A. niger, A. flavus and F. oxysporum as dose-dependence. Altogether, MC.AgNPs and PG.AgNPs will have much potential in scaled up production and become the promising fungicides for agricultural applications.
Sooty blotch and flyspeck (SBFS) is a fungal disease complex that can cause significant economic losses to apple growers by blemishing the fruit surface with dark-colored colonies. Little is known about the phenology of host infection for this diverse group of epiphytes. In 2009 and 2010, we investigated the timing of infection of apple fruit by SBFS species in six commercial apple orchards in Iowa. Five trees in each orchard received no fungicide sprays after fruit set. Within 3 weeks after fruit set, 60 apples per tree were covered with Japanese fruit bags to minimize inoculum deposition. Subsequently, a subsample of bagged apples was exposed for a single 2-week-long period and then rebagged for the remainder of the growing season. Experimental treatments included seven consecutive 2-week-long exposure periods; control treatments were apples that were either bagged or exposed for the entire season. After apples had been stored at 2°C for 6 weeks following harvest, all SBFS colonies on the apples were identified to species using a PCR-RFLP protocol. A total of 15 species were identified. For the seven most prevalent species, the number of infections per cm2 of fruit surface was greatest on apples that had been exposed early in the season. Two SBFS species, Peltaster fructicola and Colletogloeopsis-like FG2, differed significantly from each other in time required to attain 50% of the total number of colonies per apple, and analysis of variance indicated a significant interaction of SBFS taxon with exposure period. Our findings are the first evidence of species-specific patterns in timing of SBFS inoculum deposition and infection on apple fruit, and strengthen previous observations that most SBFS infections resulting in visible colonies at harvest develop from infections that occur early in the fruit development period. By defining taxon-specific phenological patterns of fruit infection, our findings, when combined with knowledge of region-specific patterns of taxon prevalence, provide a foundation for development of more efficient and cost-effective SBFS management tactics.
Black pod rot is the most economically important disease of cocoa in Malaysia which is
mainly caused by a highly polyphagous Phytophthora species, called Phytophthora palmivora.
The fungus could attack all parts of the cocoa plant organs and caused various diseases at
any growth stage from seedling until the mature stages, especially during raining season. The
application of synthetic fungicides has been widely recommended to manage the disease but
their repeated use had led to other problems such as environmental, human health and
development of fungicide resistance issues. This study isolated and identified Phytopththora
isolate from a cocoa pod sample based on micro-morphological characters. Besides, the
present investigation was undertaken to screen for the antifungal potency of different weed
extracts against the Phytophthora pathogen using poisoned food technique. The fungal isolate
was successfully recovered from pod tissues of clone PBC123 on 20% tomato juice agar
culture (20T). Only one out of ten weed extracts tested showed a significant in vitro inhibitory
effect towards mycelial growth of Phytophthora isolate, which was aqueous crude leaf extract
of Solanum torvum (42.68%). This study indicated that the potential of weed extracts in the
management of Phytophthora diseases, and may offer more natural, effective and economical
control methods.
The filamentous spoilage fungi in vegetables can lead to significant impact in food and economic loss. In order to overcome this problem, chemical fungicide has been implemented in vegetable farming and processing but it causes problems towards environment and food safety. Thus, the utilization of natural products such as plants extracts, which exhibit antimicrobial and antifungal activity, is more acceptable to solve this problem. The aim of this study is to investigate the antifungal activity of Boesenbergia rotunda extract against ten filamentous spoilage fungi isolated from five vegetables. The extract was used to treat fungal isolates from vegetables; CRb 002 (Penicillium sp.), CHa 009 (Aspergillus sp.), TMa 001 (Geotrichum sp.), TMa 002 (Aspergillus sp), ONb 001 (Aspergillus sp.), WBb 003 and WBb 004 (Fusarium sp.) WBb 007 (unidentified), WBb 008 (Aureobasidium sp.) and WBb 010 (Penicillium sp.). The results showed that the yield of the extract of B. rotunda using ethanol (95%) was 11.42% (w/v). The 10% of B. rotunda extract exhibited antifungal activities against ten filamentous fungi after 5 days treatment with growth reduction of 41.56%, 30.68%, 86.20%, 50.62%, 26.67%, 47.44%, 50.74%, 36.39%, 42.86%, and 39.39% for WBb 008, WBb 004, WBb 007, WBb 003, CRb 002, WBb 010, CHa 009, TMa 001, ONb 001, and TMa 002, respectively. B. rotunda extract showed highest antifungal activity against fungi isolated from winged bean (WBb 007) with percentage reduction in growth was 86.20%, while the lowest activity was against fungi isolated from the carrot (CRb 002) with 26.67% reduction in growth. Generally, the TPC of fungi in the vegetable samples were reduced after treatment with 5% of B. rotunda extract at 5 min and 10 min of exposure time. The results suggested that B. rotunda extract has high potential to become natural food preservative which can reduce the fungi spoilage of vegetables.
The fungicide captan, which is commonly used to control fungal diseases in many plants, causes soil infertility and cancer to human beings. Hence, this fungicide was tested for utilization as a sole carbon source by a newly soil isolate, Planomicrobium flavidum strain EF. This bacterium resists captan up to 2000 ppm and showed higher growth patterns in minimum salt medium supplemented with captan only, if compared with minimum salt medium without captan. Moreover, almost 77.5% of captan has been utilized by Planomicrobiu flavidum after only 2 h of growth under shaking conditions and only 0.8% of the fungicide was remained after 24 h of bacterial growth. Captan residues in both soil samples and minimal salt medium were accurately estimated using GC-ECD (gas chromatography - electron detector) and GC-MS/MS (gas chromatography - mass spectrum) technologies. According to current results, Planomicrobium flavidum strain EF is highly recommended for captan and may be other fungicides bioremediation.
To investigate the antifungal activity of conventional chitosan and chitosan-loaded nanoemulsions against anthracnose caused by Colletotrichum spp. isolated from different tropical fruits.
Oil palm trunk fibre (OPTF)--an agricultural solid waste--was used as low-cost adsorbent to remove malachite green (MG) from aqueous solutions. The operating variables studied were contact time, initial dye concentration, and solution pH. Equilibrium adsorption data were analyzed by three isotherms, namely the Freundlich isotherm, the Langmuir isotherm, and the multilayer adsorption isotherm. The best fit to the data was obtained with the multilayer adsorption. The monolayer adsorption capacity of OPTF was found to be 149.35 mg/g at 30 degrees C. Adsorption kinetic data were modeled using the Lagergren pseudo-first-order, Ho's pseudo-second-order and Elovich models. It was found that the Lagergren's model could be used for the prediction of the system's kinetics. The overall rate of dye uptake was found to be controlled by external mass transfer at the beginning of adsorption, then for initial MG concentrations of 25, 50, 100, 150, and 300 mg/L the rate-control changed to intraparticle diffusion at a later stage, but for initial MG concentrations 200 and 250 mg/L no evidence was found of intraparticle diffusion at any period of adsorption. It was found that with increasing the initial concentration of MG, the pore-diffusion coefficient increased while the film-diffusion coefficient decreased.
In this paper, we concisely reviewed the contamination of persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) in human breast milk collected from Asian countries such as Japan, China, Philippines, Vietnam, Cambodia, India, Malaysia, and Indonesia during 1999-2003. Dioxins, PCBs, CHLs in Japanese, and DDTs in Vietnamese, Chinese, Cambodian, Malaysian, and HCHs in Chinese, Indian, and HCB in Chinese breast milk were predominant. In India, levels of dioxins and related compounds (DRCs) in the mothers living around the open dumping site were notably higher than those from the reference site and other Asian developing countries, indicating that significant pollution sources of DRCs are present in the dumping site of India and the residents there have been exposed to relatively higher levels of these contaminants possibly via bovine milk.
Fungicide is used to control fungal disease by destroying and inhibiting the fungus or fungal spores that cause the disease. However, failure to deliver fungicide to the disease region leads to ineffectiveness in the disease control. Hence, in the present study, nanotechnology has enabled the fungicide active agents (hexaconazole) to be encapsulated into chitosan nanoparticles with the aim of developing a fungicide nanodelivery system that can transport them more effectively to the target cells (Ganoderma fungus). A pathogenic fungus, Ganoderma boninense (G. boninense), is destructive to oil palm whereby it can cause significant loss to oil palm plantations located in the Southeast Asian countries, especially Malaysia and Indonesia. In regard to this matter, a series of chitosan nanoparticles loaded with the fungicide, hexaconazole, was prepared using various concentrations of crosslinking agent sodium tripolyphosphate (TPP). The resulting particle size revealed that the increase of the TPP concentration produced smaller particles. In addition, the in vitro fungicide released at pH 5.5 demonstrated that the fungicide from the nanoparticles was released in a sustainable manner with a prolonged release time up to 86 h. On another note, the in vitro antifungal studies established that smaller particle size leads to lower half maximum effective concentration (EC50) value, which indicates higher antifungal activity against G. boninense.
A newly developed electrochemical sensor for chlorothalonil based on nylon 6,6 film deposited onto screen printed electrode (SPE) with electrochemical modulation of pH at the electrode/solution interface was studied for the first time. Differential pulse cathodic stripping voltammetry (DPCSV) was used to carry out the electrochemical and analytical studies. Experimental parameters such as accumulation potential, initial potential, accumulation time and pH of Britton-Robinson buffer have been optimized. Chlorothalonil gave optimum analytical signal in a medium of 0.04 M Britton-Robinson buffer at pH 6.0. A well-defined reduction peak was observed, at Ep= -0.851 and -0.938 V vs. Ag/AgCl (3.0 M KCl) for both bare SPE and modified SPE, respectively. The peak currents of modified SPE were significantly increased as compared to bare SPE. At the modified SPE, a linear relationship between the peak current and chlorothalonil concentration was obtained in the range from 0.1 to 2.8 × 10-6 M with a detection limit of 1.53 × 10-8 M (S/N= 3). The practical applicability of the newly developed method has been demonstrated on analyses of real water samples. The newly developed sensor shows good reproducibility with RSD of 3.92%. The nylon 6,6 modified SPE showed itself as promising sensor with good selectivity for chlorothalonil determination.
The present study investigates the effects of different concentrations, as well as type of plant growth regulators (PGRs) and medium (MS, Duchefa) on the growth and development of Centella asiatica in semi-solid culture. In addition, a protocol for successful sterilization of C.asiatica explants prepared from field-grown plants highly exposed to fungal and bacterial contamination was determined. Results for sterilization treatments revealed that applying HgCl₂ and Plant Preservative Mixture (PPM) with cetrimide, bavistin and trimethoprim which were included after washing with tap water, followed by the addition of PPM in the medium, produced a very satisfactory result (clean culture 90 ± 1.33%) and TS5 (decon + cetrimide 1% + bavistin 150 mg/L + trimethoprim 50 mg/L + HgCl₂0.1% + PPM 2% soak and 2 mL/L in medium) was hence chosen as the best method of sterilization for C.asiatica. The synergistic combination of 6 benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) in concentrations of 2 mg/L and 0.1 mg/L, respectively, in Duchefa medium compared with MS induced the most optimal percentage of sprouted shoots (93 ± 0.667), number of shoots (5.2 ± 0.079) and nodes (4 ± 0.067) per explant, leaf per explant (14 ± 0.107) and shoot length (4.1 ± 0.67 cm). Furthermore, optimum rooting frequency (95.2 ± 0.81%), the number of roots/shoot (7.5 ± 0.107) and the mean root length (4.5 ± 0.133 cm) occurred for shoots that were cultured on full-strength MS medium containing 0.5 mg/L indole-3-butyric acid (IBA). In this study, the acclimatized plantlets were successfully established with almost 85% survival. The findings of this study have proven an efficient medium and PGR concentration for the mass propagation of C.asiatica. These findings would be useful in micropropagation and ex situ conservation of this plant.
A method for the chiral separation of propiconazole using cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) with hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) as chiral selector is reported. The use of a mixture of 30 mM HP-gamma-CD, 50mM SDS, methanol-acetonitrile 10%:5% (v/v) in 25 mM phosphate buffer solution was able to separate two enantiomeric pairs of propiconazole. Stacking- and sweeping-CD-MEKC under neutral pH (pH 7) and under acidic condition (pH 3.0) were used as two on-line preconcentration methods to increase detection sensitivity of propiconazole. Good repeatabilities in the migration time, peak area and peak height were obtained in terms of relative standard deviation (RSD). A sensitivity enhancement factor of 100-fold was achieved using sweeping-CD-MEKC at acidic pH. This is the first report on the separation of two pairs of propiconazole enantiomers and all the enantiomers of fenbuconazole and tebuconazole using sweeping-CD-MEKC. The limit of detection (S/N=3) for the three triazole fungicides ranged from 0.09 to 0.1 microg/mL, which is well below the maximum residue limits (MRL) set by Codex Alimentarius Commission (CAC). Combination of solid-phase extraction (SPE) pretreatment and sweeping-CD-MEKC procedure was applied to the determination of selected triazole fungicides in grapes samples spiked at concentration 10-40 times lower than the MRL established by the CAC. The average recoveries of the selected fungicides in spiked grapes samples were good, ranging from 73% to 109% with RSD of 9-12% (n=3).
Piper betle (sirih) is a medicinal plant that has been reported for various pharmacological activities such as antifungal, antibacterial, antioxidant, anticarcinogenic and, anti-inflammatory. The researchwas carried out to study the antifungal activity of ethanolic extract from P. betle leaves. Matured leaves of P. betle were collected and processed to a fine powder before being extracted using ethanol. The first part of the research involved evaluation of antifungal activity of the ethanolic extracts using disk diffusion method at four different concentrations (5, 25, 50, 100 mg/mL) against 3 types of fungi isolated from laboratory surfaces. The sensitivities of the fungal towards the ethanolic extracts were determined by measuring the size of inhibitory zones. Results showed that highest concentration of the extract (100 mg/mL) inhibited fungal growth for all three types of isolated fungi with 0.97, 0.83, and 0.77 cm zone of inhibition for yeast, Aspergillus sp. and Penicillium sp., respectively. Low concentrations (5, 25 and 50 mg/mL) did not inhibit the fungal growth except for Penicillium sp. that showed zone of inhibition, 0.53 cm at concentration of 50 mg/mL. The second part of the research involved evaluation of fungal count utilizing effective dose of betel leaves ethanolic extract obtained from the first part of this research which is 100 mg/mL. This study found that no fungal growth on the microscope wire that has been sprayed with betel leaves ethanolic extract on Day 1, Day 4 and Day 7. For wire that been sprayed with ethanol 70%, the average of fungal count was same on Day 1 and Day 4 (5.6 x 102 cfu/mL) but increased to 9.2 x 102 cfu/mL on Day 7. In conclusion, betel leaves extract exhibit fungicidal properties that support their use as antifungal agents from natural products which are safe, easily available with no adverse effects.