• The Plant Pathology Journal
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• 제35권6호
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• pp.662-673
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• 2019

Root-knot nematodes (RKNs) are among the most destructive plant-parasites worldwide, and RKN control has been attempted mainly using chemical nematicides. However, these chemical nematicides have negative effects on humans and the environment, thus necessitating the search for eco-friendly alternative RKN control methods. Here, we screened nematicidal lactic acid bacteria (LAB) isolated from kimchi and evaluated their efficacy as biocontrol agents against RKNs. Of 237 bacterial strains, Lactobacillus brevis WiKim0069 showed the strongest nematicidal activity against the second-stage juveniles (J2) of Meloidogyne incognita, M. arenaria, and M. hapla and inhibited the egg hatch of M. incognita. The culture filtrate of WiKim0069 had a pH of 4.2 and contained acetic acid (11,190 ㎍/ml), lactic acid (7,790 ㎍/ml), malic acid (470 ㎍/ml), and succinic acid (660 ㎍/ml). An artificial mixture of the four organic acids produced by WiKim0069 also induced 98% M. incognita J2 mortality at a concentration of 1.25%, indicating that its nematicidal activity was derived mainly from the four organic acids. Application of WiKim0069 culture filtrate suppressed the formation of galls and egg masses on tomato roots by M. incognita in a dose-dependent manner in a pot experiment. The fermentation broth of WiKim0069 also reduced gall formation on melon under field conditions, with a higher efficacy (62.8%) than that of fosthiazate (32.8%). This study is the first report to identify the effectiveness of kimchi LAB against RKNs and to demonstrate that the organic acids produced by LAB can be used for the RKN management.

• 한국응용곤충학회지
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• 제25권3호
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• pp.169-173
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• 1986

감자썩이선충(Ditylenchus destructor)에 의해 폐포(廢圃)된 강원도 철원지역(鐵原地域) 인삼포(人蔘圃)에 훈증제(熏蒸劑) 및 비훈증제(非熏蒸劑) 약제(藥劑)를 처리하고 인삼(人蔘)을 식부(植付)한 후, 재배기간중(栽培期間中)에 ethoprop, aldicarb, carbofuran, phenamiphos, triazophos, oxamyl 등(等)을 인삼(人蔘) 2년근시(年根時)와 3년근시(年根時)에 한달 간격으로 각각(各各) 2회(回)와 3회(回)씩 처리(處理)하였다. 예정지(豫定地)에 cylon, ethoprop 및 triazophos 처리구(處理區)는 1984년 인삼(人蔘) 3년근시(年根時) 선충의 밀도(密度)는 무처리구(無處理區), formalin 훈증구(熏蒸區) 및 carbofuran 처리구(處理區)보다 상대적으로 낮았으며 3년(年), 4년근(年根)의 출아율(出芽率)과 3년근(年根)의 병발생억제(病發生柳制)에 효과가 있었다. cylon 훈증후(熏蒸後) 재배기간중(栽培期間中) 약제처리(藥劑處理)는 cylon 단독 처리포장(處理圃場)에 비해 선충의 밀도(密度)감소와 출아율(出芽率) 및 병발생억제(病發生柳制)에는 효과가 크지 않았으나 채굴시 4년근(年根)의 잔존율(殘存率) 및 인삼근(人蔘根) 수량(收量)에는 차이를 안정할 수 있었다. 칸당(當) 1kg 이상의 인삼근(人蔘根) 수량(收量)은 cylon 처리후(處理後) 재배기간중(栽培期間中) aldicarb 또는 ethoprop 처리구(處理區)와 예정지(豫定地)부터 ethoprop을 처리(處理)한 포장(圃場)에서 얻을 수 있었다. 인삼생육(人蔘生育)과 선충밀도와의 상관은 조사당시 뿐만 아니라 조사시기(調査時期)를 전후로 하여 유의성(有意性)있는 상관을 보여 토양중(土壤中) 감자썩이 선충이 인삼(人蔘)의 생육(生育)에 직접적으로 영향을 주는 것으로 생각된다.

• The Plant Pathology Journal
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• 제34권1호
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• pp.35-43
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• 2018

Root-knot nematodes (Meloidogyne spp.) are parasites that attack many field crops and orchard trees, and affect both the quantity and quality of the products. A root-colonizing bacterium, Pseudomonas chlororaphis O6, possesses beneficial traits including strong nematicidal activity. To determine the molecular mechanisms involved in the nematicidal activity of P. chlororaphis O6, we constructed two mutants; one lacking hydrogen cyanide production, and a second lacking an insecticidal toxin, FitD. Root drenching with wild-type P. chlororaphis O6 cells caused juvenile mortality in vitro and in planta. Efficacy was not altered in the fitD mutant compared to the wild-type but was reduced in both bioassays for the mutant lacking hydrogen cyanide production. The reduced number of galls on tomato plants caused by the wild-type strain was comparable to that of a standard chemical nematicide. These findings suggest that hydrogen cyanide-producing root colonizers, such as P. chlororaphis O6, could be formulated as "green" nematicides that are compatible with many crops and offer agricultural sustainability.

• Journal of Applied Biological Chemistry
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• 제56권4호
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• pp.199-204
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• 2013

The nematicidal, antifungal and antioxidant activities of methanol extracts from six Vietnamese native medicinal plants were evaluated by various assays in vitro. Of the plant extracts tested, Terminalia nigrovenulosa was found to possess the highest activity when compared to the others. The leaves and bark of T. nigrovenulosa showed strong inhibitory activity against Meloidogyne incognita and Fusarium solani. The DPPH (1,1-Diphenyl-2-picryl-hydrazyl) radical scavenging, reducing power and total antioxidant activities of T. nigrovenulosa bark were higher than that of the remainder plant extracts. Chitinase activity of these plants was also investigated using SDS-PAGE. The results obtained in the present study indicate that T. nigrovenulosa leaf extracts are the greatest potential source as nematicides and fungicides for the control of M. incognita and F. solani. In particularly, T. nigrovenulosa bark extracts could be used as a potential source of commercially viable levels of natural antioxidant.

• Journal of Applied Biological Chemistry
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• 제48권4호
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• pp.161-166
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• 2005

Among 24 isolates of fluorescent Pseudomonads, 5 isolates named as LPT1, LPT2, LPT3, LPT4 and LPT5 were screened in vitro for their nematicidal activity against cyst forming nematode, Heterodera cajani causing patchiness, poor and stunting growth besides discoloration in Sesamum indicum. Second stage juveniles of H. cajani hatched from egg masses were collected from roots of host plant and subjected to fresh and heat-treated culture filtrate of isolates for 24 h. Mortality of H. cajani was recorded on the basis of parameters used for test organism bioassay. Among these isolates, Pseudomonas aeruginosa LPT5 caused maximum mortality towards second stage juvenile of H. cajani in vitro. Five isolates were used as seed coating for the management of cyst forming nematode H. cajani on sesame in green house condition. The strains LPT5 was better than the other strains in reducing the population of H. cajani both in vitro and in vivo. The reduction in cyst and juveniles population was found to be 49 and 60%, respectively when seeds were coated with strain LPT5. Among other strains, LPT4 was also found to inhibit the cyst and juveniles population 12 and 36% respectively. Increases in early vegetative plant growth parameters recorded in both in vitro and in vivo further revealed the significance of indigenous bacteria in comparison to introduced strain.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.255-258
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• 2020

Pine wilt disease (PWD) caused by pine wood nematode (PWN), Bursaphelenchus xylophilus, which is transmitted by Monochamus alternatus and M. saltuarius, is a serious threat to coniferous forests in the Northern Hemisphere, including Korea. The efficacy of abamectin and emamectin benzoate for preventing the PWD in the field and its effect on the vectors Monochamus alternatus and M. saltuarius (Coleoptera: Cerambycidae) were evaluated. An experimental plot was delimited, of which consists of Japanese red pine (Pinus densiflora) forest in South Korea, and trunk injection trials were made with abamectin and emamectin benzoate. Branches of each tree were collected, and are subsequently subjected to the analysis of residues for both nematicides. Results obtained in this study showed that abamectin and emamectin benzoate showed over 90% mortality at the recommended concentration after 6 days and 8 days, respectively. Consequently, it was found that both insecticides have a higher effect on the susceptibility and persistence of two vectors of PWD, M. alternatus and M. saltuarius feeding on branches of the trees, and its application by trunk injection is confirmed as an option for pine wilt disease management programs in Korea.

• 식물병연구
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• 제7권1호
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• pp.42-48
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• 2001

참외 연작지에서 문제가 되는 뿌리혹선충의 효율적인 방제법을 구명하기 위하여, 땅콩뿌리혹선충이 감염된 성주과채류시험장 온실에서 실험을 실시하였다. 재배적 방제로는 참깨, 파, 옥수수 및 벼를 참외 심기 전에 윤작작물로 재배하였고, 물리적 방제는 건토, 태양열처리 및 객토였으며, 화학적 방제약제로는 forthizate 입제를 사용하였다. 방제효율은 방제 방법간 큰 차이가 있었는데, 벼 윤작, 태양열처리, 객토에서 방제효과가 가장 높아 뿌리혹선충 밀도는 90% 감소하였고 참외 수량은 무처리에 비해 2배 증수되었다. 그러나 이러한 처리구에서 선충밀도가 6월 이후 다시 증가하여 처리효과는 참외 한 작기에만 유효하였다. 다음으로 효과가 높은 것은 옥수수 윤작, 건토, forthizate 처리였다. Forthizate 처리는 초기 수량에서 유의한 증수 효과가 인정되었으나(P=0.05) 후기 수량과 전체 수량에서는 증수 효과가 없었다. 윤작작물로 참깨와 파는 선충 방제 효과가 없었다.

• The Plant Pathology Journal
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• 제39권3호
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• pp.290-302
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• 2023

Abamectin offers great protection against Bursaphelenchus xylophilus, a well-known devastating pathogen of pine tree stands. Trunk injection of nematicides is currently the most preferred method of control. This study aimed to evaluate the potency of the commonly used formulations of abamectin against B. xylophilus. Twenty-one formulations of abamectin were evaluated by comparing their sublethal toxicities and reproduction inhibition potentials against B. xylophilus. Nematodes were treated with diluted formulation concentrations in multi-well culture plates. And, populations preexposed to pre-determined concentrations of the formulations were inoculated onto Botrytis cinerea culture, and in pine twig cuttings. Potency was contrastingly different among formulations, with LC₉₅ of 0.00285 and 0.39462 mg/ml for the most, and the least potent formulation, respectively. Paralysis generally occurred at an application dose of 0.06 ㎍/ml or higher, and formulations with high sublethal toxicities caused significant paralysis levels at the tested doses, albeit the variations. Nematode reproduction was evident at lower doses of 0.00053-0.0006 ㎍/ml both on Botrytis cinerea and pine twigs, with significant variations among formulations. Thus, the study highlighted the inconsistencies in the potency of similar product formulations with the same active ingredient concentration against the target organism, and the need to analyze the potential antagonistic effects of the additives used in formulations.

• The Plant Pathology Journal
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• 제39권1호
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• pp.75-87
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• 2023

The pine wood nematode (PWN), Bursaphelenchus xylophilus is a well-known devastating pathogen of economic importance in the Republic of Korea and other countries. In the Republic of Korea, trunk injection of nematicides is the preferred method of control. In this study, the efficacy of 16 locally produced formulations of emamectin benzoate against the PWN are compared through determining their sublethal toxicities and reproduction inhibition potentials. Nematodes were treated with varying concentrations of the tested chemicals in multi-well culture plates, and rates of paralysis and mortality were determined after 24 h. Reproduction inhibition potential was tested by inoculating pre-treated nematodes onto Botrytis cinerea, and in pine twig cuttings. Despite the uniformity in the concentration of the active ingredient, efficacy was contrastingly different among formulations. The formulations evidently conformed to three distinct groups based on similarities in sublethal activity (group 1: LC₉₅ of 0.00768-0.01443 mg/ ml; group 2: LC₉₅ of 0.03202-0.07236 mg/ml, and group 3: LC₉₅ of as high as 0.30643-0.40811 mg/ml). Nematode paralysis generally occurred at the application dose of 0.0134-0.1075 ㎍/ml, and there were significant differences in nematode paralysis rates among the products. Nematode reproduction was only evident at lower doses both on B. cinerea and pine twigs, albeit the variations among formulations. Group 1 formulations significantly reduced nematode reproduction even at a lower dose of 0.001075 ㎍/ml. The variations in efficacy might be attributed to differences in inert ingredients. Therefore, there is need to analyze the potential antagonistic effects of the large number of additives used in formulations.

• 한국응용곤충학회지
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• 제38권1호
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• pp.47-52
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• 1999

토양중 유기물 함량 차이에 따른 토양내에서 carbofuran과 ethoprophos의 약효 변화, 수직 이동성 및 잔효성에 미치는 영향을 조사하기 위하여 고구마뿌리혹선충 (Meloidogyne incognita)을 공시하여 실험하였다. 두 약제 모구 토양중 유기물 함량이 많을수록 약효는 감소였다. 약제의 수직이동성은 토양 표면에서 0~2cm층에서는 유기물의 함량에 관계없이 두 약제 모두 80%이상의 높은 방제가를 보였으나, 2~4cm층에서는 유기물의 함량에 관계없이 두 약제 모두 80%이상의 높은 방제가를 보였으나, 2~4cm 층에서는 두 약제의 방제가가 다르게 나타났다. Carbofuran의 경우 유기물 함량에 따라 10~30%의 방제가를 나타냈으나, ethoprophos는 0.4% 유기물 토양에서만 약 30%의 방제가를 나타냈으며, 나머지 유기물 토양에서는 효과가 거의 없었다. 또한 4cm 이하의 토양에서는 carbofuran은 대부분의 토야에서 5~20%의 내외의 약효를 나타냈으나, ethoprophos은 거의 나타내지 않았다. 따라서 , 두 약제 중에서 토양중 이동성은 carbofuran이 더 큰 것으로 나타났다. 토양중 유기물 함량은 두 약제의 잔효지속기간에 큰 영향을 주었으며, 유기물 함량이 증가함에 따라 약효지속기간이 감소하였다. 약효의 반감기는 carbofuran의 경우 유기물 함량이 0.4%인 토양에서는 2~3주로 나타났으나, 0.8%, 1.6% 토양에서는 1주 정도였다. 한편, ethoprophos의 경우 0.4%, 0.8%의 토양에서는 3~4주, 1.6%인 토양에서는 1~2주로 나타났다. 그러나 두 약제 모두 3.2%의 유기물함량 토양에서 약제의 효과가 거의 나타나지 않았다.