• Research in Plant Disease
• /
• v.15 no.1
• /
• pp.13-16
• /
• 2009

In April 2008, cherry (Prunus yedoensis Matsumura) in Jeju exhibited severe disease of branches forming numerous twigs. Five isolates from diseased leaves were identified as Taphrina wiesneri on the basis of biological and genetic characteristics. Twenty one commercial fungicides were tested for control of the disease in vitro. Of the 21 fungicides, triazole compounds (difenoconazole, propiconazole and tebuconazole) showed relatively good antimicrobial activities. Results from the planta bioassays indicated that triazole compounds reduced the witches' broom disease showing control value $25.7{\sim}52.8%$ compared with the nontreated controls.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.2
• /
• pp.315-321
• /
• 1994

In order to prevent the postharvest decay and to promote the freshness retention of fruits and vegetables grapefruit seed extract(GFSE), natural microorganism control agent, was applied to the preservation of fresh fruits and vegetables. Freshfruits and vegetables treated with GFSE and stored in polyethylene film (0.1mm) at 1$0^{\circ}C$-15$^{\circ}C$ of natural low temperature low kept better qualities in color and texture than the GFSE -not- treated control. The treatment using GFSE ina 250ppm to 500ppm concentration seemed to be an effective one for the control of Botrytis cinerea isolated in red wine grapes. After 4 weeks of storage the firmness rate of cucumbers treated with the dilute GFSE was four times higher than that of non-treated ones. GFSE showed effective inhibitory action towards plant pathological bacteria and fungi which were involved in the decay of fruits and vegetables. Minimum inhibitory concentrations of GFSE towards them were in the range of 250ppm to 500ppm .Direct visualization of microbial cells and spores using electron microscopy showed microbial cells and fungal spores the function of which was destroyed by treating with the dilute solutions of GFSE. It was observed that GFSE would reduced disease damages and have bactericide & fungicide properties during the storage of such fruits and vegetables as egg plant, wild edible greens , kumquat, and kiwi fruit.

• Journal of Ginseng Research
• /
• v.29 no.4
• /
• pp.185-191
• /
• 2005

In vitro and in vivo effectiveness of fungicides were evaluated for the control of damping off caused by Rhizoctonia solani on Panax ginseng. Fludioxonil(67 mg a. i./L), flutolanil(75 mg a. i./L), thifluzamide(35 mg a. i./L), and mepronil (750 mg a. i./L) were selected from 9 fungicides, which were based on inhibition of mycelial growth of R. solani (isolate Rh 9801) and duration of fungicidal effectiveness against the pathogen in vitro. Field trials were made twice in the year of 2003 and 2004. Experimental plots $(54m{\times}0.9m)$ of 4-year-old ginseng fields were artificially infested with 5kg and 14 kg in fresh weight of inoculum in 2003 and 2004, respectively. The fungicides were drenched at a volume of 8l in $3.6m{\times}0.9m$ with 3 replications. Fludioxonil, flutolanil, thifluzamide and mepronil reduced the incidence of damping off by $73\%,\;69\%,\;69\%\;and\;43\%$, respectively. In the 2004 trial, fludioxonil, flutolanil, and thifluzamide showed similar result as reducing the incidence by $85\%,\;84\%,\;and\;82\%$, respectively, in the plot where the inoculum was applied 2.8 times more than the 2003. The disease incidences in untreated control were $12\%$ in 2003 and $47\%$ in 2004.

• The Plant Pathology Journal
• /
• v.37 no.4
• /
• pp.356-364
• /
• 2021

This study was to investigate defense mechanisms on cassava induced by salicylic acid formulation (SA) against anthracnose disease. Our results indicated that the SA could reduce anthracnose severity in cassava plants up to 33.3% under the greenhouse condition. The 𝛽-1,3-glucanase and chitinase enzyme activities were significantly increased at 24 hours after inoculation (HAI) and decrease at 48 HAI after Colletotrichum gloeosporioides challenge inoculation, respectively, for cassava treated with SA formulation. Synchrotron radiation-based Fourier-transform infrared microspectroscopy spectra revealed changes of the C=H stretching vibration (3,000-2,800 cm^-1), pectin (1,740-1,700 cm^-1), amide I protein (1,700-1,600 cm^-1), amide II protein (1,600-1,500 cm^-1), lignin (1,515 cm^-1) as well as mainly C-O-C of polysaccharides (1,300-1,100 cm^-1) in the leaf epidermal and mesophyll tissues treated with SA formulations, compared to those treated with fungicide carbendazim and distilled water after the challenged inoculation with C. gloeosporioides. The results indicate that biochemical changes in cassava leaf treated with SA played an important role in the enhancement of structural and chemical defense mechanisms leading to reduced anthracnose severity.

• Horticultural Science & Technology
• /
• v.30 no.1
• /
• pp.21-26
• /
• 2012

To elucidate the role of silicon in biotic stress such as pests and diseases, standard chrysanthemum was grown in pots filled with soil without application of pesticide and fungicide. Si treatment was largely composed of three groups: $K_2SiO_3$ (50, 100, and $200mg{\cdot}L^{-1}$), three brands of silicate fertilizer (SiF1, SiF2, and SiF3) and tap water as a control. Si sources were constantly drenched into pots for 14 weeks. Application high concentration $K_2SiO_3$ ($200mg{\cdot}L^{-1}$) and three commercial Si fertilizers for 14 weeks improved growth parameters such as plant height and the number of leaves. In the assessment of disease after 4 weeks of Si treatment, percentage of infected leaves was not significantly different from that of control. After 14 weeks of Si treatment, however, the infected leaves were significantly reduced with a 20-50% decrease in high concentration ($200mg{\cdot}L^{-1}$) of potassium silicate and all commercial silicate fertilizers. Colonies of aphid insect (Macrosiphoniellas anborni) were also reduced in Si-treated chrysanthemum, showing 40-57% lower than those of control plants. Accumulation of silicon (approximately $5.4-7.1mg{\cdot}g^{-1}$ dry weight) in shoots of the plants was higher in Si-supplemented chrysanthemum compared to control plants ($3.3mg{\cdot}g^{-1}$ dry weight). These results indicate that using potassium silicate or silicate fertilizer may be a useful for management of disease and aphid insect in soil-cultivated chrysanthemum.

• Research in Plant Disease
• /
• v.9 no.2
• /
• pp.64-67
• /
• 2003

Clubroot disease of Chinese cabbage has extremely occurred in recent years. Conventional soils such as sandy loam soil (saprolite) and clay soil (yellow soil) as bed media combined with field soil application of fungicidal chemicals were tested for the control of clubroot disease. Using sandy loam soil and clay soil as plug seedling bed media efficiently reduced clubroot disease occurrence down to 21.7% and 14.1%, respectively compared to peatmoss (75.7%) and Baroco soil (36.6%) when seedling plants were transplanted into previously-infected Yoncheon field. Application of flusulfamide and azoxystrobin to previsouly-infected soil prior to transplanting also effectively reduced disease incidence, especially when combined with growing seedlings in sandy loam or clay soil media. In conclusion, flusulfamide application prior to trnasplanting as well as utiliz-ing sandy loam and clay soil as a plug bedding media may effectively reduce the occurrence of clubroot dis-ease of Chinese cabbage.

• Journal of Environmental Science International
• /
• v.21 no.12
• /
• pp.1435-1447
• /
• 2012

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemII under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates $H_2O_2$ generation. UV-B exposure induced accumulation of $H_2O_2$ in the leaves, while HEX prevented UV-B induced increase in $H_2O_2$, indicating that HEX serves as an antioxidant agent able to scavenge $H_2O$ to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing $H_2O_2$ during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

• Research in Plant Disease
• /
• v.14 no.2
• /
• pp.85-89
• /
• 2008

Clubroot of Chinese cabbage, caused by Plasmodiophora brassicae, is one of the most serious plant diseases in the world. The objectives of this study were to investigate the effect of the irrigation times on the development of club root after planting and to evaluate the effect of clubroot disease on yield of chinese cabbage in pot and field. The clubroot disease gradually increased with increasing irrigation frequency after planting. The growth characters and yield of chinese cabbage by irrigation times varied according to soil moisture and clubroot disease severity. Based on marketable yield and control value, an ideal irrigation point was at the soil matric potential of 0.06 MPa. These results suggest that the suppression on clubroot disease development could be achieved by initially reduced irrigation times after planting. Future studies on irrigation times using fungicide treatment and resistant cultivar under natural field conditions are required to improve the control effect of clubroot.

• Korean Journal of Agricultural Science
• /
• v.20 no.1
• /
• pp.18-24
• /
• 1993

This experiment was focused on determining the potential of sodium hypochlorite (NaOCl) as fungicide against seed-borne fungi. Effects of NaOCl to control seed-borne fungi were compared to the those of Benlate T in several crop seeds. 1. The effect of NaOCl on disinfection of sesame seeds without imparing germination was highest in the range of 1-2% solution for 10 min. Also, a 30 min immersion of rice seed in 1-2% solution reduced incedence of seed-borne fungi. 2. Alternaria spp. in seeds of radish and chinese cabbage and Colletoricum spp. in pepper were significantly reduced by a 10 min immersion of seeds in 1% NaOCl. 3. The effective control range of NaOCl for seed-borne fungi was much wider than that of Benlate T in sesame seeds. No clear difference between chemicals was found in rice seeds. However, germination of seeds were impaired at 1-2% NaOCl immersion for more than 1 hour.

• Research in Plant Disease
• /
• v.20 no.1
• /
• pp.54-58
• /
• 2014

Anthracnose crown rot (ACR), caused by Colletotrichum fructicola, is a serious disease of strawberry in Korea. The primary inoculums of ACR were symptomless strawberry plants, plant debris, and other host plants. To effectively control anthracnose in symptomless transplanted strawberries, it is necessary to use disease-free plants, detect the disease early, and apply a fungicide. Therefore, in 2010 and 2011, we evaluated the efficacy of pre-plant fungicide dips by using strawberry transplants infected by C. fructicola for the control of anthracnose. Dipping plants in prochloraz-Mn for 10 min before planting was most effective for controlling anthracnose in symptomless strawberry plants and resulted in more than 76% control efficacy. Azoxystrobin showed a control efficacy of over 40%, but plants treated with pyraclostrobin, mancozeb and iminoctadine tris showed high disease severity. The control efficacy of the dip treatment with prochloraz-Mn did not differ with temperature and time. Treatment with prochloraz-Mn for more than an hour caused growth suppression in strawberry plants. Therefore, the development of anthracnose can be effectively reduced by dipping strawberry plants for 10 min in prochloraz-Mn before planting.