• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.313-319
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• 2017

Strawberries are one of the main commodities in Korea and have been exported over 30 million dollar. And the safety has recently become an important issue in the agro-trade, pesticide residue is most important matter of safe agricultural products. As strawberries can be cultivated using elevated production system, so it is possible to use the drenching. When spraying the pesticides, the use of drenching can be lower amount of residual than using foliar treatment. In this study, time sequential residual amount of pesticides were compared between drenching and foliar application in strawberries. Pesticides were treated with the standard and double dosage and samples were collected at 0, 3, 6, 9, 13, 16 and 21 day and analyzed by LC and LC-MS/MS after liquid-liquid extraction and QuEChERS. Two pesticides were detected less than 1 mg/kg in all samples for drenching treatment. Carbendazim residues in drenching treatment were 5 to 25 times lower than foliar application. And azoxystrobin was not detected in strawberries of drenching treatment.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.11-17
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• 2019

Strawberries are one of the main commodities in Korea and have been exported over 40 million dollar. Because the strawberry cultivation using hydroponics has increased, treatment of pesticide by drenching draw interest recently. However, detailed researches for drenching treatment of pesticide are limited, which results in difficulties in proper pesticide applications in agricultural fields. To activate use of drenching and improve safety in agricultural products, In this study, time-dependent residual characteristic of pesticides were compared with between different applications of pesticides in strawberries. The characteristics of azoxystrobin, prochloraz and thiamethoxam were investigated with drenching treatment at different applications: the time of treatment, concentration etc. at hydroponic cultivation for 40 days. Azoxystrobin and prochloraz were not detected at 14 day after application. Thiamethoxam was detected from 0.02 to 0.85 mg/kg. Crop uptake of pesticides was strongly affected with octanol-water partition coefficient and solubility in water. Residual amount in crops are highly dependent on the concentration of active ingredient of pesticides.

• Journal of Bio-Environment Control
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• v.14 no.4
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• pp.284-288
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• 2005

This study was conducted to clarify the effects of supplying methods of selenium on the growth and Se uptake of hydroponically grown tomato plants. Tomato seeds (Lycopersicum esculentum Mill. cv. Momotaro T-93, Daki Seed Co.) were sown in plug tray with fifty holes, and raised for sixty days. Tomato seedlings transplanted to coco fiber slabs were supplied with the nutrient solutions adjusted to EC $2.3dS{\cdot}m^{-1}$ and pH $5.8\~6.2$ recommended by the Japanese Horticultural Experiment Station. Selenium forms used were inorganic $SeO_2$ (here in after referred to Se) and organic selenium chlenium with sugar fatty acid ester (here in after referred to chelated-Se). 10 ppm selenium solutions were treated to tomato plants with foliar applications, drenching, and foliar application plus drenching. Growth characteristics in terms of plant height, number of leaves, leaf area and chlorophyll content were significantly increased in the plot of foliar application ot Se, and in the plot of foliar application plus drenching of chelated-Se than other plots, respectively. Transported contents of selenium into the tomato fruits were highest as 0.302 ppm in the plot of foliar application plus drenching of chelated-Se. Also, it had tended to be higher in the plot of foliar application plus drenching than in the plots of foliar application or drenching in both of Se and chelated-Se. Foliar application and drenching of organic chelated-Se were effective to produce the functional tomato fruits.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.228-241
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• 2016

In our previous study, we reported that a novel endophytic bacterium Bacillus oryzicola YC7007 has suppressed bacterial diseases of rice via induced systemic resistance and antibiotic production. This endophytic strain, B. oryzicola YC7007 was used as a biological control agent against bakanae disease of rice caused by Fusarium fujikuroi, and its mechanism of interaction with the pathogen and the rice was further elucidated. Root drenching with B. oryzicola YC7007 suspension reduced the disease severity of bakanae significantly when compared with the untreated controls. The treatments of B. oryzicola YC7007 suspension ($2.0{\times}10^7cfu/ml$) to the rice rhizosphere reduced bakanae severity by 46-78% in pots and nursery box tests containing autoclaved and non-autoclaved soils. Moreover, in the detached rice leaves bioassay, the development of necrotic lesion and mycelial expansion of F. fujikuroi were inhibited significantly by spraying the culture filtrate of B. oryzicola YC7007. Drenching of ethyl acetate extracts of the culture filtrate to the rhizosphere of rice seedlings also reduced the bakanae disease severity in the plant culture dish tests. With the root drenching of B. oryzicola YC7007 suspension, the accumulation of hydrogen peroxide was observed at an early stage of rice seedlings, and a hormonal defense was elicited with and without pathogen inoculation. Our results showed that the strain B. oryzicola YC7007 had a good biocontrol activity against the bakanae disease of rice by direct inhibition, and was also capable of inducing systemic resistance against the pathogen via primed induction of the jasmonic acid pathway.

• Journal of Applied Biological Chemistry
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• v.61 no.1
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• pp.75-78
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• 2018

Ethephon is useful pesticide as ethylene precursor, which is an efficient plant hormone to produce functional secondary metabolites. However, the residual safety of ethephon was not studied on various crops. In here, the dissipation pattern of ethephon residue in soybean leaf was investigated both on the foliar and drenching applications. The biological half-lives of ethephon residues were 26.6, and 21.1 h on the once, and double foliar applications, respectively. Although the residue after three days from the final application was up to $60.6mg\;kg^{-1}$, the residue was below the limit of quantitation on the dried soybean leaf. In addition, drenching application of ethephon could increase the residue up to $36.3mg\;kg^{-1}$ after 20.1 h from the application, however, the treatment would not affect to the total phenol content significantly (p >0.01).

• Research in Plant Disease
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• v.8 no.1
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• pp.50-54
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• 2002

A total of 55 Colletotrichum isolates from strawberry plants with anthracnose symptoms(crown rot) were inhibited in mycelial growth on potato-dextrose agar(PDA) amended with fungicides in variable degrees depending on the chemicals used, especially showing no growth on PDA with 1 mg/m/tricyclazole. However, in the detached leaf test by treating chemicals before or after inoculation of Colletotrichum sp., tricyclazole was little effective in controlling symptom development; instead azoxystrobin, which had low in vitro inhibition of mycelial growth, inhibited strongly the symptom development. Some chemicals were tested for the control of strawberry crown rot in greenhouse using three methods, sprays soil drenching and plant dipping. No or little control effect were made by chemical spray and soil drenching, but plant dipping in chemical solution, especially azoxystrobin: reduced crown rot development by about 50% in the greenhouse suggesting that the azoxystrobin treatment may be an effective control method of the crown rot of strawberry. No differences in the control efficacy were noted according to the dipping time and chemical concentration of azoxystrobin not less than 10 min and 250 mg/m/, respectively.

• FLOWER RESEARCH JOURNAL
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• v.19 no.3
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• pp.127-138
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• 2011

Four different plant growth retardants (PGRs), paclobutrazol, flurprimidol, daminozide, and chlormequat, were applied to potted Saxifraga rosacea 'Kumoma' and 'Kumoma-Gusa' plants for control of the growth and flowering. Paclobutrazol (10, 20, 40, $80mg{\cdot}L^{-1}$), flurprimidol (5, 10, 20, $40mg{\cdot}L^{-1}$), daminozide (500, 1000, 2000, $4000mg{\cdot}L^{-1}$), and chlormequat (50, 100, 200, $400mg{\cdot}L^{-1}$) were applied to the plants by a foliar spray or drenching. In 'Kumoma', application of $40mg{\cdot}L^{-1}$ paclobutrazol by a foliar spray or drenching reduced plant height by 12.5 and 12.6 cm, and flower length by 3.4 and 3.3 cm, respectively. On the other hand, in 'Kumoma-Gusa', drenching of paclobutrazol reduced plant height by 10.7 to 12.6 cm and flower length by 2.0 to 3.9 cm with increasing concentration, but the number of florets almost fell to 20 as compared to 40.5 in the control. 'Kumoma-Gusa' plants drenched with $80mg{\cdot}L^{-1}$ paclobutrazol and sprayed with $40mg{\cdot}L^{-1}$ flurprimidol had the shortest heights of 10.7 and 9.9 cm, and floral length of 2.0 and 1.5 cm, respectively. A flurprimidol drenching at $40mg{\cdot}L^{-1}$ delayed the harvest by 3-13 days as compared to the control and the smallest number of florets, 15.6, was observed in this treatment. In both cultivars, chlormequat and daminozide did not effectively influence the growth and flowering. However, number of florets increased to more than 41 at all concentrations and up to 63, the greatest floret number, with chlormequat drench in 'Kumoma-Gusa'. These results demonstrated that over $40mg{\cdot}L^{-1}$ of paclobutrazol or 5 to $20mg{\cdot}L^{-1}$ of flurprimidol could be used as PGRs to control the growth of floral length and flowering for improving potted plant quality in S. rosacea 'Kumoma' and 'Kumoma-Gusa'.

• Research in Plant Disease
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• v.16 no.3
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• pp.279-284
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• 2010

Clubroot caused by Plasmodiophora brassicae is a widespread disease that causes serious problems in many brassica growing areas. To establish more simple and reliable clubroot screening method of Chinese cabbage to P. brassicae using soil-drenching inoculation, the development of clubroot on Chinese cabbage according to several conditions such as soil type, inoculum concentration of P. brassicae GN-1 (race 9), plant growth stage and incubation period was studied. In a commercial horticulture nursery media soil (CNS), disease severity of the seedling according to inoculum concentration increased in a dose-dependent manner, but did not in mixture of CNS and upland soil (1:1, v/v). To facilitate and acquire precise result of resistance screening of Chinese cabbage to clubroot, 10-day-old seedlings should be inoculated by drenching the spore suspension of P. brassicae to give inoculum density of $4.0{\times}10^8$ spores/pot. To develop the disease, the inoculated seedlings were incubated in a growth chamber at $20^{\circ}C$ for 3 days, and then cultivated in a greenhouse ($25{\pm}5^{\circ}C$) for five weeks. Under the optimum conditions, 25 clubroot-resistant (CR) and 3 clubroot-susceptible (CS) cultivars were tested for resistance to P. brassicae. All CR cultivars showed very clear resistance response, on the other hand all CS cultivars severly infected with the pathogen. The results suggest that this method is efficient screening method of Chinese cabbage for resistance to clubroot disease.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.271-276
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• 2012

A mycoparasite, Paraconiothyrium minitans CM2 was selected for biological control of sclerotinia rot of lettuce caused by Sclerotinia sclerotiorum. The experiment was carried out in a lettuce greenhouse in Yangpyeong from March to April.. When lettuce sclerotinia rot showed in the early stage of occurrence, Conidial suspension of the mycoparasite was weekly treated once to three times onto soil surface around lettuce plants. Incidence of sclerotinia rot in the once-application plot of the mycoparasite ($1{\times}10^7$ spores/$m{\ell}$) and in the benomyl(WP)-treated plot was 11.0% and 2.7%, respectively, whereas that of control was 31.0%. Incidence of twice- and three-application plots of the isolate was 7.9% and 12.8%, respectively. For increasing the effect of the mycoparasite, the experiment for the timing of application of P. minitans CM2 was carried out in a lettuce greenhouse in Yangpyeong and Suwon. Control efficacy against lettuce sclerotinia rot in the soil-drenching plots of P. minitans CM2 ($5{\times}10^6$ spores/$m{\ell}$) in the planting was 75.3~84.7%, and control effect by treatment of the isolate at the pot drenching+the soil-drenching plots in the early stage of disease occurrence was 63.8~58.0%. As the results, P. minitans CM2 could be a prospective biofungicide for biological control of sclerotinia rot of lettuce.

• The Korean Journal of Mycology
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• v.44 no.4
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• pp.330-337
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• 2016

Streptomyces sp. A75 and A501 inhibited the mycelial growth of pathogenic Rhizoctonia solani and Pythium sp., which cause the ginseng disease known as damping-off. Three methods were evaluated for the control of these pathogens, using a mixture of the culture broths from Streptomyces sp. A75 and A501. The methods tested were seed dipping with 50-fold diluted broth, drenching of soil with 100-fold diluted broth after sowing, and combined seed dipping and drenching. These methods reduced the incidence of ginseng damping-off caused by R. solani by 81.3%, 84.8%, and 32.2% and that caused by Pythium sp. by 51.0%, 52.1%, and 75.3%, respectively. Based on these results, the combination of seed dipping and soil drenching after sowing using a mixture of the culture broths from Streptomyces sp. A75 and A501 effectively reduced the incidence of damping-off in ginseng.