• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.401-406
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• 2010

This study was conducted to investigate the control effects of the environmental-friendly materials against major diseases of pear and to elucidate factors related to spore disperse of pear scab and pear rust. Spore disperse was deeply related ambient temperature in the early stage of disease occurrence and the maximum spore disperse was affected greatly by the air humidity, Percent of infected leaves of pear scab in plot treated with Trichoderma harzianum-YC459 was 29.3% and 43.3% in plot treated with Sulfur-80%. Two formulations above-mentioned were less effective to control pear scab than the chemical pesticide, hexaconazole. Control effect in plots single- and mixed-treated with Trichoderma harzianum-YC459, Sulfur-80% and hexaconazole against pear scab were compared with that in plot treated with chemicals by conventional application schedule in pear orchard. The incidence of pear scab was lower in plot treated with the environmental-friendly materials than that of untreated plot. However there was no significant difference among the treatments at the 5% level. Application of Sulfur-80% reduced significantly the incidence of pear scab (7.8%) compared to that (10.3%) in plot treated by conventional application schedule in organically cultivated pear orchard. Alternative application of Trichoderma harzianum-YC459 and Sulfur-80% (4.3%) suppressed the incidence of pear rust than that (7.1%) in plot treated by conventional application schedule in organically cultivated pear orchard.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.687-702
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• 2012

The objective of this study was to determine crop rotation effects on potato yield, soil chemical and microbiological properties from a short-term field experiment from 2010 to 2011 in Jeju Island, Korea. Potato cropping systems included continuous and rotation sequences of soybean (Glycine max(L.) Merr.), barley (Hordeum vulgare var. hexastichon), rapeseed (Brassica napus L.) and broccoli (Brassica oleracea var. italica). Crop rotations increased the yields of potato from 31% to 52% compared with continuous potato. Marketable yield of potato was highest under soybean plus rapeseed rotation by $20.97MT\;ha^{-1}$ and lowest under continuous cropping by $11.95MT\;ha^{-1}$. The incidence and severity of scab disease was significantly lower in tubers from crop rotation with soybean plus barley. Differences in marketable tuber yields among rotations were associated with potato scab disease. Especially, incidence and severity of potato scab were strongly correlated with soil pH, exchangeable calcium, and bacteria population of the soil. Crop rotations significantly increased soil pH, available phosphate, exchangeable K and Ca, especially in crop rotations with soybean plus barley or rapeseed. Soil microbial biomass C of crop rotations with soybean plus barley or rapeseed, was also significantly higher compared with monoculture. In conclusion, crop rotation may decrease the incidence of soil-born pathogen by increasing soil chemical properties and soil microbial biomass. Overall, potato crop productivity was generally maintained in rotations that contained soybean plus barley or rapeseed but declined under continuous cropping system.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.94.1-95
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• 2002

• The Plant Pathology Journal
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• v.22 no.4
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• pp.375-380
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• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• Journal of Plant Biotechnology
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• v.4 no.2
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• pp.45-52
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• 2002

A lot of SSRs (simple sequence repeats) in peach and pear from enriched genomic libraries and in peach from a cDNA library were developed. These SSRs were applied to other related species, giving phenograms of 52 Prunes and 60 pear accessions. Apple SSRs could also be successfully used in Pyrus spp. Thirteen morphological traits were characterized on the basis of the linkage map obtained from an $F_2$ population of peach. This map was compiled with those morphological markers and 83 DNA markers, including SSR markers used as anchor loci, to compare different peach maps. Molecular markers tightly linked to new root-knot nematode resistance genes were also found. A linkage map including disease related genes, pear scab resistance and black spot susceptibility, in the Japanese pear Kinchaku were constructed using 118 RAPD markers. Another linkage map, of the European pear Bartlett, was also constructed with 226 markers, including 49 SSRs from pear, apple, peach and cherry. Maps of other Japanese pear cultivars, i.e., Kousui and Housui, were also constructed. These maps were the first results of pear species.

• Research in Plant Disease
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• v.16 no.1
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• pp.48-58
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• 2010

In Korea, EBI fungicides which are highly effective for control of pear scab and rust but of high risk for development of resistance have been frequently sprayed by majority of pear growers. To detect any possible resistance or reduced sensitivity in the field strains of scab fungus to five EBIs, difenoconazole, fluquinconazole, flusilazole, fenarimole and hexaconazole, sensitivity tests were conducted with fungal specimens collected in Ulsan and Naju where scab usually occurs and EBIs have been intensively sprayed for many years. As the strains for which $EC_{50}$ values of the EBIs were largely shifted from those of base-line were occasionally found, the resistant or less sensitive strains were supposed to be distributed. In the activity test for the EBIs by artificial inoculation, in which EBI-treated pear leaves on the potted seedlings were inoculated with fungal spores collected in the two regions, development of resistances to EBIs were confirmed. Since the fungal spores collected at 4 and 2 orchards in Naju and Ulsan, respectively, produced much higher disease incidence on the leaves treated with hexaconazole than those on the untreated control, those fungal specimens were determined as resistant to hexaconazole. Similar results were also obtained with two specimens from Ulsan for flusilazole.

• Research in Plant Disease
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• v.18 no.2
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• pp.117-122
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• 2012

In 2006, the effect of soil pH adjustment on control of common scab of potato caused by Streptomyces spp. was evaluated in the field. Soil with an original pH 5.7 was treated with sulfur of 42 kg/10a and calcium hydroxide of 81.6 kg/10a and 184.5 kg/10a to adjust pH 5.0, 6.0 and 6.5, respectively. Additionally, the effect of gypsum (522 kg/10a) on soil pH and disease severity was examined. The soil pH of sulfur treatment plot was continuously declined from 5.13 at tuber initiation time to 5.01 at harvest. The disease severity of sulfur treatment plot was relatively low (22.8%) and the marketable yield of that was high (90.5%). By contrast, the soil pHs treated with calcium hydroxide (81.6 kg/10a and 184.5 kg/10a) were increased (pH 6.06 and 6.49, respectively) at harvest. In addition, calcium hydroxide treatment plots showed higher disease severities (51.0% and 61.1%), and lower marketable yields (55.7% and 37.0%). Meanwhile, the soil pH of gypsum treatment plot was not changed until harvest, and the disease severity and the marketable yield were not significantly different from those of control. The effect of crop rotation was also evaluated with four crops such as welsh onion, soybean, corn and Chinese cabbage. These crops were planted in the infested field from 2005 to 2007, and potatoes were planted in the same field in 2008. The disease severities of potatoes produced after rotations with welsh onion, soybean, corn and Chinese cabbage for 3 years were 13.1%, 16.7%, 28.9% and 30.2%, respectively. However, the disease severity of 73.1% was shown in continuous cropping of potato for 3 years. In addition, similar effects were exhibited in the marketable yield. These results demonstrate that the adjustment of soil pH and crop rotation might be very useful tools to control common scab of potato.

• Korean Journal of Organic Agriculture
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• v.19 no.3
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• pp.405-416
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• 2011

Organic materials, such as chitin incubated solution (CIS) combined with neem oil (NO), nano silver silica (NSS), and Bordeaux mixture (BDM), were applied with and without agricultural chemicals (AC) (insecticide and fungicide) to investigate scab and mealybug occurrences and fruit qualities on 'Niitaka' pear trees in orchards in 2006. Fruits and leaves grown under CIS+NO without AC had less than 30%, scab occurrence, but CIS+NSS or CIS+BDM without AC had higher scab occurrence. Organic materials with AC decreased the scab to less than 20%. All treatments decreased mealybug occurrences to less than 10%, except for the fruits grown under CIS+BDM without AC. Fruit qualities varied among the treatments. Hunter value a, representing for the redness degree, was higher for fruits treated with CIS+NSS and CIS+BDM without AC than those with AC. Fruits treated with organic materials without AC had greater total phenolic and flavonoid compounds as well as antioxidant capacity in flesh and greater total phenolc compounds and antioxidant capacity in peel than those treated with the AC.

• Research in Plant Disease
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• v.17 no.3
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• pp.302-310
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• 2011

Elsinoe fawcettii is one of major pathogenic fungi which cause citrus scab diseases, resulting in fruit blemishes that reduce the economic value of fruit. By increasing interest to safe products of crops, the alternative methods of disease control is highly required. We investigated whether the 215 bacterial strains isolated from Jeju Island possess antifungal effect or suppression effect on the symptom development by Elsinoe fawcettii on citrus. Among them, three bacterial strains THJ 609-3, MRL408-3, and TRH423-3 that exhibited antifungal capacity against Elsinoe fawcettii were selected. To illustrate the disease suppression mechanism, pre-inoculation with the selected bacterial strains was carried out whether could suppress the citrus crab on the leaves. The observation with a fluorescence microscope revealed that the selected bacteria could decrease the number of fungal spores. The ratio of germ tube formation was also decreased by the selected bacterial strains at one day after fungus challenge. The strain THJ 609-3 was identified as Pseudomonas putida as a result of analyzing the internal transcript spaces of the rhizobacterial rDNA. The strains MRL 408-3 and TRH 423-3 were identified as Burkholderia gladioli. Our results may be valuable when the selected rhizobacterial strains used as the environment-friendly microbe for biological control on citrus scab caused by Elsinoe fawcettii.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.36-36
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• 2022

The molecular understanding of resistance and susceptibility of host plants to scab, a most threatful disease to pome fruit production worldwide, is very limited. Comparing resistant line '93-3-98' to susceptible one 'Sweet Skin' at seven time points of 0, 0.5, 1, 2, 3, 4, 8 days post inoculation, RNA-sequencing data derived from infected and mock-inoculated young leaves were analyzed to evaluate the tolerant response and to mine candidate genes of pear to the scab pathogen Venturia nashicola. Analysis of the mapped reads showed that the infection of V. nashicola led to significant differential expression of 17,827 transcripts with more than 3-fold change in the seven pairs of libraries, of which 9,672 (54%) are up- and 8,155(46%) are down-regulated. These included mainly receptor (NB-ARC domains-containing, CC-NBS-LRR, TIR-NBS-LRR, seven transmembrane MLO family protein) and transcription factor (ethylene responsive element binding, WRKY DNA-binding protein) related gene. An arsenal of defense response of highly resistant pear accessions derived from European pear was probably supposed no sooner had V. nashicola infected its host than host genes related to disease suppression like Polyketide cyclase/dehydrase and lipid transport protein, WRKY family transcription factor, lectin protein kinase, cystein-rich RLK, calcium-dependent phospholipid-binding copine protein were greatly boosted and eradicated cascade reaction induced by pathogen within 24 hours. To identify transcripts specifically expressed in response to V. nashicola, RT-PCRs were conducted and compare to the expression patterns of seven cultivars with a range of highly resistant to highly susceptible symptom. A DEG belonging to the PR protein family genes that were higher expressed in response to V. nashicola suggesting extraordinary role in the resistance response were led to the identification. This study provides the first transcriptional profile by RNA-seq of the host plant during scab disease and insights into the response of tolerant pear plants to V. nashicola.