• The Plant Pathology Journal
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• v.28 no.2
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• pp.164-171
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• 2012

Rice blast disease caused by Magnaporthe grisea (Hebert) Barr [teleomorph] is one of the most devastating diseases in rice plantation areas. Silicon is considered as a useful element for a large variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants receiving the different rates and sources of silicon. Silicon at all rates of application significantly (${\alpha}$ = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization.

• International Journal of Industrial Entomology and Biomaterials
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• v.40 no.2
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• pp.41-50
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• 2020

Vermicompost, manure, compost and organic fertilization are ecofriendly. Nowadays, many products resulted from sericulture consumed by humans such as mulberry leaves, fruits, mulberry tea, silk and natural silk cosmetics. Soil applications of three treatments with vermicompost (0.5, 1 and 2 tons per 0.42 hectare) and recommended rate of mineral fertilizers of nitrogen phosphorus potassium were used for investigation. Impact of fertilization on mulberry plant traits of moisture, number of shoots/tree, total shoots length/tree, number of leaves/shoot, number of leaves/ (100g), leaf yield/tree and leaf yield of fadden/season were recorded. In addition the effect of fertilization on larval and cocoon characters of young instar duration, fifth instar duration, total larval duration, larval mortality percentage, weight of third instar larvae, weight of fourth instar larvae, weight of fifth instar larvae, fresh cocoon weight, fresh shell weight, pupae weight, cocoon shell ratio, silk productivity, cocooning percentage, pupation ratio, number of cocoons/ liter, crop cocoons by number, crop cocoons by weight, fecundity and fertility. Using vermicompost treatment was enhancing plant characters. Treatments of V₃, V₂ and V₁ were shortage young, fifth and larvae durations. Mostly feeding silkworm during the whole larval duration on treated mulberry leaves with vermicompost improving the traits average. Using vermicompost for fertilization by rate of V₃ and V₂ is better than others for cocoon characters for females and males.V₃ and V₂ of vermicompost per 0.42 hectare is recommended for rearing mulberry silkworm instead of mineral fertilization.

• The Plant Pathology Journal
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• v.34 no.6
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• pp.514-531
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• 2018

Tomato spotted wilt virus (TSWV; Genus Orthotospovirus: Family Tospoviridae) is one of the most destructive viruses affecting a wide range of horticultural crops on a worldwide basis. In 2015 and 2016, 171 leaf and fruit samples from tomato (Solanum lycopersicum) plants with viral symptoms were collected from the fields in various regions of Iran. ELISA test revealed that the samples were infected by TSWV. The results of RT-PCR showed that the expected DNA fragments of about 819 bp in length were amplified using a pair of universal primer corresponding to the RNA polymerase gene and DNA fragments of ca 777 bp and 724 bp in length were amplified using specific primers that have been designed based on the nucleocapsid (N) and non-structural (NSs) genes, respectively. The amplified fragments were cloned into pTG19-T and sequenced. Sequence comparisons with those available in the GenBank showed that the sequences belong to TSWV. The high nucleotide identity and similarities of new sequences based on the L, N, and NSs genes showed that minor evolutionary differences exist amongst the isolates. The phylogenetic tree grouped all isolates six clades based on N and NSs genes. Phylogenetic analysis showed that the Iranian isolates were composed a new distinct clade based on a part of polymerase, N and NSs genes. To our knowledge, this is the first detailed study on molecular characterization and genetic diversity of TSWV isolates from tomato in Iran that could be known as new clade of TSWV isolates.

• Journal of Ginseng Research
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• v.33 no.2
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• pp.127-131
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• 2009

The plant protection rate of the marketed microbial products for ginseng cultivation was investigated against Rhizoctoina solani and Pythium sp. in a seedling pot experiment. A significant difference was found among the mean plant protection rates (Pm) of the microbial products, including Tolclofos-methyl (Rhizolex). The best microbial product, C-ISR2, showed a 33% and 33.6% net Pm (total Pm-control Pm) in the two tests against Rhizoctonia solani. In one test with a 58.6% control plot Pm, the total pm was 91.6%, indicating that plant protection can be done only with a microbial product in a well-conditioned field. The net Pm of C-ISR2 against Pythium sp. was 26.4%. The net Pm of a microbial product against a pathogen seems to be fixed. A significant negative linear correlation was found between the Pm and the coefficient of variation (CV) of the protection rate in all the three experiments. This indicates that the protection processes of control, microbial products, and chemical pesticides are in the same system. Pm was only dependent on CV, probably due to each seedling's microenvironment. In the linear correlation equation between the Pm and the CV of the microbial products and the control plot, the intercept of the vertical axis will be the theoretical Pm when CV is zero.

• The Plant Pathology Journal
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• v.30 no.2
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• pp.200-207
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• 2014

A viral disease causing severe mosaic, necrotic, and yellow symptoms on Vigna angularis var. nipponensis was prevalent around Suwon area in Korea. The causal virus was characterized as Cucumber mosaic virus (CMV) on the basis of biological and nucleotide sequence properties of RNAs 1, 2 and 3 and named as CMV-wVa. CMV-wVa isolate caused mosaic symptoms on indicator plants, Nicotiana tabacum cv. Xanthi-nc, Petunia hybrida, and Cucumis sativus. Strikingly, CMV-wVa induced severe mosaic and malformation on Cucurbita pepo, and Solanum lycopersicum. Moreover, it caused necrotic or mosaic symptoms on V. angularis and V. radiate of Fabaceae. Symptoms of necrotic local or pin point were observed on inoculated leaves of V. unguiculata, Vicia fava, Pisum sativum and Phaseolus vulgaris. However, CMV-wVa isolate failed to infect in Glycine max cvs. 'Sorok', 'Sodam' and 'Somyeong'. To assess genetic variation between CMV-wVa and the other known CMV isolates, phylogenetic analysis using 16 complete nucleotide sequences of CMV RNA1, RNA2, and RNA3 including CMV-wVa was performed. CMV-wVa was more closely related to CMV isolates belonging to CMV subgroup I showing about 85.1-100% nucleotide sequences identity to those of subgroup I isolates. This is the first report of CMV as the causal virus infecting wild Vigna angularis var. nipponensis in Korea.

• Research in Plant Disease
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• v.19 no.3
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• pp.196-200
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• 2013

This study was carried out to investigate yield loss due to soybean leaf spot disease caused by Cercospora sojina Hara and to determine the economic threshold level. The investigations revealed highly significant correlations between disease severity (diseased leaf area) and yield components (pod number per plant, total grain number per plant, total grain weight per plant, percent of ripened grain, weight of hundred seed, and yield). The correlation coefficients between leaf spot severity and each component were -0.90, -0.90, -0.92, -0.99, -0.90 and -0.94, respectively. The yield was inversely proportional to the diseased leaf area increased. The regression equation, yield prediction model, between disease severity (x) and yield (y) was obtained as y = -3.7213x + 354.99 ($R^2$ = 0.9047). Based on the yield prediction model, economic injury level and economic threshold level could be set as 3.3% and 2.6% of diseased leaf area of soybean.

• Korean Journal Plant Pathology
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• v.3 no.1
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• pp.3-7
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• 1987

Ethanol-soluble amino acids and phenolics in healthy and blast-infected leaves of the susceptible rice cultivar Nakdong and adult-plant-resistant cultivar Dobong were quantitatively analyzed, At the 3 days after inoculation, the levels of soluble amino acids and phenolics in the infected fifth and eighth leaves of the two cultivars ere similar to those of comparable healthy controls. As blast lesions appeared on the leaves at the 5 days after inoculation, the soluble amino acids and phenolics began to increase. At the 7 days after inoculation, the levels of amino acids and phenolics were about 1.5-3 times more than those in healthy controls at the five-and eight leaf stages. The adult-plant-resistant cultivar Dobong showed higher amounts of soluble amino acids and phenolics in both healthy and infected fifth and eighth leaves than did the susceptible cultivar Nakdong, although Dobong was less infected by Pyricularia oryzae than Nakdong, The pronounced increases in amino acids and phenolics in rice leaves of the cultivar Dobong during the blast infection may play an important role in the expression of adult-plant resistance to blast.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.451-457
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• 2018

The Sweet potato chlorotic fleck virus (SPCFV), of the genus Carlavirus (family Betaflexiviridae), was first detected as one of several viruses infecting sweet potatoes (Ipomea batatas L.) in Korea. Out of 154 sweet potato samples collected in 2012 that were showing virus-like symptoms, 47 (31%) were infected with SPCFV, along with other viruses. The complete genome sequences of four SPCFV isolates were determined and analyzed using previously reported genome sequences. The complete genomes were found to contain 9,104-9,108 nucleotides, excluding the poly-A tail, containing six putative open reading frames (ORFs). Further, the SPCFV Korean isolates were divided into two groups (Group I and Group II) by phylogenetic analysis based on the complete nucleotide sequences; Group I and Group II had low nucleotide sequence identities of about 73%. For the first time, we determined the complete genome sequence for the Group II SPCFV isolates. The amino acid sequence identity in coat proteins (CP) between the two groups was over 90%, whereas the amino acid sequence identity in other proteins was less than 80%. In addition, SPCFV Korean isolates had a low amino acid sequence identity (61% CPs and 47% in the nucleotide-binding protein [NaBp] region) to that of Melon yellowing-associated virus (MYaV), a typical Carlavirus.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.56-60
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• 1985

The present researches were carried out to examine the favorable nutritional conditions for mycelial growth of Cercospora kikuchii, and inhibition of bacterial growth by the fungus at various cultural conditions. As the nitrogen source, the fungus grew better on yeast-extract than the other sources of nitrogen tested. Sucrose, glucose, maltose and fructose were good sources of carbon for mycelial growth of the fungus. Two isolates of C. kikuchii, wild types A and D, inhibited the growth of bacteria on the medium containing yeast-extract or peptone as the nitrogen source, and sucrose, glucose, maltose or fructose as the carbon source, at pH 5.0. However, the albino mutant showed very little inhibitory effect under the same conditions.

• The Plant Pathology Journal
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• v.36 no.6
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• pp.515-535
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• 2020

Essential oils (EOs) have gained a renewed interest in many disciplines such as plant disease control and medicine. This review discusses the components of ginger EOs, their mode of action, and their potential nanotechnology applications in controlling tropical plant diseases. Gas chromatography-mass spectroscopy (GC-MS), high-performance liquid chromatography, and headspace procedures are commonly used to detect and profile their chemical compositions EOs in ginger. The ginger EOs are composed of monoterpenes (transcaryophyllene, camphene, geranial, eucalyptol, and neral) and sesquiterpene hydrocarbons (α-zingiberene, ar-curcumene, β-bisabolene, and β-sesquiphellandrene). GC-MS analysis of the EOs revealed many compounds but few compounds were revealed using the headspace approach. The EOs have a wide range of activities against many phytopathogens. EOs mode of action affects both the pathogen cell's external envelope and internal structures. The problems associated with solubility and stability of EOs had prompted the use nanotechnology such as nanoemulsions. The use of nanoemulsion to increase efficiency and supply of EOs to control plant diseases control was discussed in this present paper. The findings of this review paper may accelerate the effective use of ginger EOs in controlling tropical plant diseases.