• Research in Plant Disease
• /
• v.20 no.2
• /
• pp.112-118
• /
• 2014

A liquid bio-formulation containing chitinolytic bacteria, chitin and their products was assessed for its potential biological control against root-knot nematodes on cucumber. The bio-formulation was prepared by cultures of three chitinolytic bacteria, Chromobacterium sp. strain C-61, Lysobacter engymogenes and Serratia plymuthica in minimal medium supplemented with chitin. Under pot conditions, the bio-formulation showed better growth of cucumber plants, and less root galls and population density of Meloidogyne spp. than control media without the bio-formulation. In a greenhouse, 75-fold diluted bio-formulations were treated instead of water around cucumber plants through hoses for drip irrigation six times at 5-day intervals from the transplanting date. After 30 and 60 days, the treatment provided about 7% and 10% enhancement in the plant height and about 78% and 69% reduction in population density of Meloidogyne spp. in the rhizosphere, respectively. In addition, the experiments showed that the control effects occurred only in the soils contacted with the bio-formulation. Undiluted bio-formulations were drenched three times at 10-day intervals around cucumber plants severely infested with Meloidogyne spp. The treatment showed about 37% plant enhancement without dead plants compared with 37% death in the untreated control, and about 82% nematode reduction. These results suggest that the bio-formulation can be practically used to control the root-knot nematode on cucumber.

• The Korean Journal of Pesticide Science
• /
• v.11 no.1
• /
• pp.18-26
• /
• 2007

Fungicidal screening was performed to control soybean black root rot caused by Calonectria ilicicola through in vitro and greenhouse assays. In in vitro assay, 25 fungicides were assessed by an agar dilution method and a 96-well microtiter plate method. While protective fungicides including dithianon, dichlofluanid, mancozeb, and captan showed a very low activity against the mycelial growth C. ilicicola SC03-15 in the agar dilution method, they displayed potent inhibitory activity against spore germination in a 96-well microtiter plate method with $EC_{50}$ values of 4.65, 0.61, 4.64, and $0.29{\mu}g\;mL^{-1}$, respectively. Ergosterol biosynthesis-inhibiting (EBI) fungicides showed different antifungal activity against mycelial growth and spore germination according to molecules. Difenconazole displayed higher antifungal activity against spore germination rather than mycelial growth, and prochloraz inhibited potently both mycelial growth and spore germination with EC50 values less than $1.8{\mu}g\;ml^{-1}$. In contrast, the other EBI fungicides inhibited more highly mycelial growth than spore germination. Carbendazim+diethofencarb and dazomet also inhibited both mycelial growth and spore germination of C. ilicicola SC03-15 at very low concentrations. In greenhouse assay, carbendazim+diethofencarb effectively controlled a soybean black root rot by drenching 2 days before or after inoculation. In addition, tebuconazole showed potent curative activity against soybean black root rot.

• Horticultural Science & Technology
• /
• v.30 no.6
• /
• pp.657-663
• /
• 2012

The Ca deficiency is a serious problem in the propagation of domestically bred 'Seolhyang' strawberry through soil cultivation. The objective of this research was to investigate the impact of the Ca containing fertilizers on the decrease of Ca deficiency symptoms and in the growth of mother and daughter plants. To achieve this, chemicals of 1.125 mM $Ca(OH)_2$, 0.375 mM $MgCl_2$, and 1.25 mM KCl were blended to contain the K:Ca:Mg (4:2:1) and the influence was compared to a commercial fertilizer, Azuro-Calma ($NO_3$-N 13%, $K_2O$ 1%, CaO 16%, MgO 6%), when those were applied as solutions with the electrical conductivity (EC) controlled to 0.6 or 1.0dS ${\cdot}m^{-1}$. During 120 days after transplant, the Azuro-Calma was more effective than the combined fertilizer in the reduction of mother and daughter plants on which Ca deficiency was appeared. The application of two Ca containing fertilizers resulted in the heavier fresh and dry weights of mother plants. The treatments of 1.0dS ${\cdot}m^{-1}$ of two fertilizers were more effective than those of 0.6dS ${\cdot}m^{-1}$. The combined fertilizer was also more effective than Azuro-calma on the growth of above ground plant tissue. The results in length, fresh and dry weight of runners occurred from a mother plants showed that the treatment of 1.0dS ${\cdot}m^{-1}$ of combined fertilizer was most effective followed by those of 1.0dS ${\cdot}m^{-1}$ of Azuro-Calma, 0.6dS ${\cdot}m^{-1}$ of combined fertilizer, 0.6dS ${\cdot}m^{-1}$ of Azuro-Calma, and control. The fresh weights of daughter plants were heavier in the treatments of Ca application than those in the control treatment, but the differences between 0.6dS ${\cdot}m^{-1}$ and control were not significant. The above results indicate that Azuro-Calma is more effective in decreasing plants showing the Ca deficiency symptoms. However, the combined fertilizer of K:Ca:Mg is more desirable when we are concerned about the decrease of crops showing Ca deficiency as well as increase of the growth in above ground plant tissue.

• The Korean Journal of Pesticide Science
• /
• v.10 no.4
• /
• pp.313-319
• /
• 2006

Two hundred bacterial strains were isolated from the soil around healthy tomato plants in a polyvinyl house, where most of the other plants showed bacterial wilt symptoms. The strains were screened in vitro for their antibacterial activity. Among them, a strain, KPB3 showed strong bactericidal activity against bacterial wilt pathogen, Ralstonia solanacearum. The strain KPB3 was identified using physiological and biochemical tests, and 16S rRNA analyses. Based on these tests, the strain was found to be closer to genus Paenibacillus. To control the bacterial wilt caused by R. solanacearum, greenhouse experiments were conducted to determine the effectiveness of the Paenibacillus strain KPB3. Drench application of this strain ($4{\times}10^8$ CFU $mL^{-1}$) into the pots containing tomato plants, post-inoculated with the pathogen, R. solanacearum could drastically reduce the disease severity, compared to the non-treated plants. To evaluate effectiveness of this strain under field conditions, experiments were carried out in polyvinyl houses infested with R. solanacearum, during spring and autumn of the year 2006. It was observed that, during spring, bacterial wilt was more prevalent compared to the autumn. During spring, 50.9% disease incidences occurred in non-treated controls, while, Paenibacillus strain KPB3 treated plants showed 24.6% disease incidences. Similarly, during autumn, around 17.2% plants were infected with bacterial wilt in non- treated polyvinyl houses, compared to the Paenibacillus strain KPB3 treated plants, which showed 7.0% disease incidences. These results demonstrated that, Paenibacillus strain KPB3 is a potential biological control agent against bacterial wilt caused by R. solanacearum, effective under greenhouse as well as field conditions. This is the first report showing biocontrol of R. solanacearum using a Paenibacillus spp. under field conditions.

• Horticultural Science & Technology
• /
• v.32 no.6
• /
• pp.872-878
• /
• 2014

This study aimed to enhance storage and freshness of strawberry fruits and foliage vegetables by spray treatment with Chlorella vulgaris as a bio-fertilizer. The tested strain, C. vulgaris CHK0008, was isolated from an organically cultivated rice paddy and identified as C. vulgaris by its morphology and 18S rDNA and 23S rDNA sequence homology. We successfully cultured C. vulgaris CHK0008 in BG11 modified medium (BG11MM) and adjusted $2.15{\times}10^6cell/mL$ C. vulgaris CHK0008 to one OD value by measuring the optical density at 680 nm using a UV-vis spectrophotometer. The soluble solid content of 'Seolhyang' and 'Yukbo' strawberry fruits treated by spray application with C. vulgaris CHK0008 was enhanced by 22.2% and 11.5% respectively, compared to untreated controls. Additionally, the decay rates of treated 'Seolhyang' and 'Yukbo' strawberry fruits decreased 63.8% and 74.4% respectively, compared to untreated control. Surface color changes and chlorosis of leaves in leaf vegetables such as lettuce, kale, red ornamental kale, white ornamental kale and beet were observed in samples treated with water spray for 10 days after cold storage. However, the decay rate of leafy vegetables treated with foliar application of 25% C. vulgaris CHK0008 liquid culture was significantly decreased compared to that of the untreated control during storage at $4^{\circ}C$.

• The Korean Journal of Pesticide Science
• /
• v.17 no.4
• /
• pp.460-467
• /
• 2013

This study was conducted to reduce the using amount of chemical fungicides for the control of red-pepper Phytophthora blight. Effect of combination application of two microbial fungicides and two chemical fungicides for the control of red-pepper Phytophthora blight was examined in vitro, in greenhouse and under field conditions. Each microbial fungicides and chemical fungicides was two-fold diluted and mixed-soil drenched. In the greenhouse pot assay, the mixed application of B. pumilus QST2808 and a mixture of dimethomorph + ethaboxam (De) among four mixed applications of two microbial fungicides (B. pumilus QST2808, P. polymyxa AC-1) and two chemical fungicides showed the highest control effect against Phytophthora blight. Also, control effect of mixed application of B. pumilus QST2808 and De was similar to that of single application of De (dimethomorph + ethaboxam) or Mo (mancozeb + oxadixyl). In the field test, when the microbial fungicides (B. pumilus QST2808, P. polymyxa AC-1) and the chemical fungicide(De) for the control of Phytophthora blight of red pepper were mixed-soil drenched four times at 7~10 day-intervals, the control values were in the range of 78.8% to 82.0%. On the other hand when each of the two chemical fungicides (De, Mo) were soil drenched four times at 7~10 day-intervals, the control value were 65.7% to 85.8%. Consequently, the mixed application of the microbial fungicides and chemical fungicides could be recommended as a control method for reducing the using amount of chemical fungicides.

• Weed & Turfgrass Science
• /
• v.5 no.3
• /
• pp.155-164
• /
• 2016

Earworm is very useful animal in soil ecosystem, however it is harmful for golf courses because they introduce many cast on turfgrass that reduces turf uniformity and play quality. However, no information has found on earthworm diversity and seasonal fluctuation in different Korean golf courses. In this study, we focused to carry out earthworm species composition and seasonal population structure in turfgrass of golf courses. During spring and fall season survey with direct digging and tea saponin drenching sampling in 5 different golf courses, 6 species under 3 families of earthworms were collected. Earthworm species composition and density was different among the golf courses. Aporrectodea caliginosa in Lumbricidae was dominant species in Anseong and Dongrae Benest Golf Club; however Amynthas carnosus in Megascolecidae was dominant species in Anyang and Glenrose Golf Club. Ap. caliginosa was collected only aclitellum in July and Am. carnosus was collected aclitellum and clitellum in August in golf courses. Seasonal population of earthworm was different depending on earthworm species (Am. hupeiensis was the highest in August and Ap. caliginosa was in April) however small number of collected earthworm species were not dominant trend in golf courses.

• Research in Plant Disease
• /
• v.29 no.2
• /
• pp.188-192
• /
• 2023

Abiotic and biotic stresses have been a serious threat to crop growth and productivity in the agricultural system. In this study, four strains (HS1, H30-3, KJ40, and BC42), which have biological activities related to disease suppression or alleviation of salinity and drought stresses, were tested for broad-spectrum biocontrol activity against anthracnose caused by Colletotrichum orbiculare, a bacterial fruit blotch caused by Acidovorax citrulli, and Fusarium wilt caused by Fusarium oxysporum in cucumber plants. As a result of test, when the four strains were drenched into the soil, anthracnose in cucumber leaves significantly decrease; strain KJ40 suppressed disease incidence by A. citrulli; strain BC42 significantly reduced bacterial fruit blotch and Fusarium wilt compared to control. Therefore, strain KJ40 could be a biocontrol candidate for controlling anthracnose through induced systemic resistance and the disease caused by A. citrulli as well as alleviating drought stress; strain BC42 has broad-spectrum biocontrol activity against anthracnose, Fusarium wilt, and bacterial fruit blotch.

• The Korean Journal of Pesticide Science
• /
• v.11 no.4
• /
• pp.305-312
• /
• 2007

It was the investigated the response to metalaxyl of Phytophthora capsici isolates collected in 2005 and 2006. With effective concentrations ($EC_{50}$) of metalaxyl causing 50% growth inhibition, resistance baseline was determined as more than $1.0\;{\mu}g\;mL^{-1}$. Based on the resistance baseline, isolation frequency (%) of P. capsici resistant to metalaxyl was 29.0% and 218% in 2005 and 2006, respectively. Among the isolates of P. capsici obtained in 2006, the isolation was variable; 33.3% in Chungnam, 26.3% in Chungbuk and 11.1% in Gyeongbuk. Two isolates of metalaxyl-sensitive (MS) and too isolates of metalaxyl-resistant (MR) P. capsici were selected and then used to investigate the activity of metalaxyl to their development stages. Even though there was a difference in mycelial growth inhibition by metalaxyl between MS and MR isolates, the fungicide was not active or nearly to sporangium germination, zoospore release, and zoospore germination of both MS and MR isolates. However, the fungicide showed weak activity against sporangium germination and zoospore release of P. capsici, not related with its resistance. Also, it was not inhibitory to zoospore germination of both resistant and sensitive isolates. In a greenhouse test, it showed 100% of control value against P. capsici 06-86 sensitive to metalaxyl, when it was applied by soil-drenching at $25\;{\mu}g\;mL^{-1}$. However, 06-130 and 16-155 resistant to metalaxyl showed less than 20% of control value.

• The Korean Journal of Pesticide Science
• /
• v.19 no.4
• /
• pp.354-360
• /
• 2015

In recent years, Allium victorialis has been extensively used as a pharmacological agent for various diseases in the form of anti-arteriosclerotic, anti-diabetic and anti-cancer. Allium victorialis is severely affected by various fungal diseases since it naturally grow in the shady and humid environments in Korea. In this case, different types of fungicides are applied to control the fungal diseases in Allium victorialis. The present study was aimed to determine the residual characteristics of two fungicides namely tebuconazole and fludioxonil on Allium victorialis. For this study, the fungicides were drenched soil on Allium victorialis in the cultivation area Pyeongchang by the standard (two thousand fold) and double (thousand fold) dilutions. At the end of $15^{th}$, $30^{th}$ and $40^{th}$ days samples were collected for residue analysis. Residues of tebuconazole and fludioxonil were analyzed using GC/NPD (Gas Chromatography/Nitrogen Phosphorus Detector) and their recovery were found to be 108.8~119.5% and 91.3~104.8%, respectively. The method of limits of quantification for both fungicides was $0.01mg\;kg^{-1}$. Further, the results of this study shows that the residue levels of both fungicides on Allium victorialis were <$0.01{\sim}0.12mg\;kg^{-1}$ and $0.01{\sim}0.09mg\;kg^{-1}$ and their % ADI (% Acceptable Daily Intake) were 17.44% and 25.75%, respectively. Based on the results obtained in this study, we suggest that the residue levels of both of the fungicides on Allium victorialis are safe and these fungicides can also be used to control fungal diseases in Allium victorialis.