• The Korean Journal of Mycology
• /
• v.47 no.4
• /
• pp.427-435
• /
• 2019

The occurrence of the crown and root rot on strawberry (Fragaria×ananassa Duch.) has been reported in greenhouses in Sancheong and Hamyang, Gyeongnam province, Korea in June, 2019. The infected plants showed browning rot of the inner crown and root, causing delayed development, lack of growth, and poor rooting. The browning rot of the inner crown and root can sometimes lead to wilting and collapsing of plants. Fungi were isolated from the symptomatic root and crown. Based on the results of morphological and phylogenetic analyses, the causal agent of the disease was identified to be Neopestalotiopsis clavispora. The fungal isolates were then used for inoculation into strawberry plants to determine the causal agent of the crown and root rot as per Koch's postulates. The inoculated strawberry plants showed the same symptoms as the originally infected plants, and the fungal pathogen re-isolated from the lesions showed the same morphological characteristics as the original pathogen. This is the first report on the occurrence of crown and root rot on strawberry (Fragaria×ananassa Duch.) caused by N. clavispora in Korea.

• The Plant Pathology Journal
• /
• v.16 no.5
• /
• pp.283-285
• /
• 2000

Two field tests were conducted in 1995 to examine the effects of composts and soil amendments on physicochemical properties of soil in relation to Phytophthora root and crown rot of bell pepper. Chitosan, crab shell waste, humate, sewage sludge-yard trimmings, and wood chips were applied to test plots, some of which affected the levels of P, K, Mg, pH, and H. Physicochemical properties were not related with disease incidence, but percent organic matter, estimated nitrogen release, K, and Mg were correlated with total microbial activity. The elements K and Mg were especially responsible for the increased soil microbial activity that could affect development of root and crown rot of pepper.

• Korean Journal Plant Pathology
• /
• v.14 no.2
• /
• pp.103-108
• /
• 1998

A Pythium species was isolated from roots of lisianthus (Eustoma grandiflorum) showing wilt symptoms and reduced growth in a greenhouse at Ichon, Kyonggi-do in 1997. The Pythium species was identified as Pythium spinosum Sawada based on various mycological characteristics. The isolate was strongly pathogenic when inoculated to root of lisianthus plants in pots. The diseased plants showed typical symptoms of root and crown rot, resulting in reduced growth of roots and shoots, and consequently wilting of the above ground part of plants.

• The Plant Pathology Journal
• /
• v.35 no.6
• /
• pp.553-563
• /
• 2019

Investigations related with factors influencing root and crown rot are rare and mainly related to farming practice and soil management. The main objective of this study was to examine broader range of factors influencing stem-base infestation of winter wheat in the field conditions. The effect of spatial distribution of infected plants on disease index (DIs) assessments was also investigated. Analysis of factors influencing DIs of crown rot of wheat demonstrated significant influence of the growing seasons (P < 0.001) and extreme fluctuations in winter temperatures (P < 0.001). In addition to that, localities together with their interaction with the growing season also significantly influenced DIs (P < 0.001). Aggregation of infected plants influenced variability of DI estimations, and it was pointed out that more extensive investigation should be conducted on broad range of DI in order to establish sampling method giving uniform sampling precision. Fusarium graminearum was shown to be predominant Fusarium species in Serbia (72.6%) using sequence-characterized amplified region analysis. Interestingly F. oxysporum was isolated in higher frequencies (27.4%) than it was reported in the literature. Given that there were no reports on the diversity of Fusarium species causing crown rot of wheat in Serbia, this study presents first report on this important subject. It also indicated that more attention should be focused on combined effects of abiotic and biotic factors influencing stem-base infestation of winter wheat. This knowledge will contribute to better understanding of factors influencing root and crown rot of wheat which would ensure sustainable disease management in the future.

• Korean Journal Plant Pathology
• /
• v.10 no.1
• /
• pp.64-67
• /
• 1994

Crown rot was found find tomatoes growing on a rockwool culture system in a glasshouse at Dongkwangyang in 1992. The disease occurred on the stem of 'Trust' tomato plants with 3~4 cluster of flowers. Infected plants showed stem girdling and necrosis at or slightly above the rockwool line. Internal tissues of crown and stem including cortex, vascular bundle, and pith became decayed resulting in a chocolate-brown discoloration extending no more than 10~15 cm above the crown. Diseased tomato plants with the similar symptoms were found at Ansung and Taejon where tomatoes were grown on either rockwool or soil in plastic greenhouses. The size of macroconidia of Fusarium isolated from a diseased plant was 26.0~41.6$\times$2.9~4.7${\mu}{\textrm}{m}$, and microconidia were formed on short monophialide and the size was 3.6~12.5$\times$2.9~3.6 ${\mu}{\textrm}{m}$. Morphological characteristics and inoculation tests indicated that the causal organism of the disease was Fusarium oxysporum.

• Korean Journal Plant Pathology
• /
• v.14 no.6
• /
• pp.735-737
• /
• 1998

A severely wilting of strawberry caused by a Phytophthora sp. has occurred houses after planting in vinyl-houses field at Ssanglim and Anlim areas Kyungbuk in Korea from October in 1997. Phytophthora sp. isolated from diseased tissues of the crown of strawberry. Browning rot of inner crown and root resulted in wilt and eventual death of the plant. The causal fungus was identified as Phytophthora cactorum. Sporangia were ovoid, conspicuously papillate, caducous and measured 30.0~56.6$\times$23.8~35.2 (av. 39.3~29.9) ${\mu}{\textrm}{m}$. Sexuality of the fungus was homothallic. Oogonia were sperical and 23.3~32.3 (av. 29.0) ${\mu}{\textrm}{m}$ in size. Most ahteridia were paragynous and measured av. 10.2~12.2 ${\mu}{\textrm}{m}$. Cardinal temperature for growth at minimum, optium, maximum were recorded at 7, 20~25, and 32$^{\circ}C$, respectively. The fungus show strong pathogenicity to strawberry. This is the first report of strawberry caused by Phytophthora cactorum in Korea.

• Journal of Ginseng Research
• /
• v.22 no.4
• /
• pp.223-228
• /
• 1998

As part of a study on the ability of fungicides to control disappearing root rot of ginseng (Panax quinquvdius) caused by Cylindruarpn destmtans, 15 fungicides were screened for toxicity to the fungus in vitro. Highly toxic fungicides were Benlate (benomyl), Thiram (thiram), and Orbit (propiconazole). EC5O values (mg a.i./L) were less than 1 and EC95 values were less than 10. Crown (carbathiin and thiabendazole), ASC-66835 (fluazinam), and UBI-2584 (tebuconazole) were moderately toxic, with EC5O values in the range 1-10 and EC95 values in the range 32-45. Weakly toxic fungicides (EC5O in the range 20-80, EC95 in the range 35-140) included UBI-2643 (thiabendazole), UBI-2565 (cyproconazole), and Vitaflo-280 (carbathiin and thiram). Anvil (hexaconazole), Vitaflo-250 (carbathiin), UBI-2383 (triadimenol), Daconil (chlorothalonil), CGA-173506 (fludioxonil), and CGA-169374 (difeno- conazole) were considered nontoxic to C. destmtan (EC5O 1.29->600, EC95>500). Relations between proportional inhibition of growth and concentration of fungicide were linear on arithmetic plots (Benlate, UBI-2643, UBI-2565, Vitaflo-280) or logarithmic plots (all other fungicides). Based on toxicity in vitro and formulation, it is recommended that Benlate, Orbit, and ASC-66835 be tested as soil drenches, and Benlate, Thiram, UBI-2584, and Crown be tested as seed treatments for controlling disappearing root rot.

• Research in Plant Disease
• /
• v.18 no.1
• /
• pp.57-61
• /
• 2012

In March 2010, grafted cucumber cultivated in the greenhouse showed a severe rot on crown resulting yellowing and wilting of the leaves. The symptoms of naturally infected plants showed dark brown, watersoaked lesions at the base of the stem. The fungus produced mass of white mycelium and yellow to orange spores in necrotic lesions on dead and dying plants. Fungus was isolated from rotted tissues of the crown and root. On the basis of morphological characteristics, ITS sequence and pathogenicity tests, the isolate was identified as Fusarium solani f. sp. cucurbitae. This is the first report of the crown and foot rot of grafted cucumber caused by F. solani f. sp. cucurbitae in Korea.

• Mycobiology
• /
• v.42 no.2
• /
• pp.158-166
• /
• 2014

In this study, bacterial strains were isolated from soils from 30 locations of Samcheok, Gangwon province. Of the isolated strains, seven showed potential plant growth promoting and antagonistic activities. Based on cultural and morphological characterization, and 16S rRNA gene sequencing, these strains were identified as Paenibacillus species. All seven strains produced ammonia, cellulase, hydrocyanic acid, indole-3-acetic acid, protease, phosphatase, and siderophores. They also inhibited the mycelial growth of Fusarium oxysporum f. sp. radicis-lycopersici in vitro. The seven Paenibacillus strains enhanced a range of growth parameters in tomato plants under greenhouse conditions, in comparison with non-inoculated control plants. Notably, treatment of tomato plants with one identified strain, P. polymyxa SC09-21, resulted in 80.0% suppression of fusarium crown and root rot under greenhouse conditions. The plant growth promoting and antifungal activity of P. polymyxa SC09-21 identified in this study highlight its potential suitability as a bioinoculant.

• The Plant Pathology Journal
• /
• v.38 no.5
• /
• pp.513-521
• /
• 2022

Our study was carried out to determine the control efficacy of sodium hypochlorite (NaOCl) for violet root rot caused by Helicobasidium mompa in apple. The experiment was conducted in the farm located at Chungbuk province in South Korea from 2014 to 2016. When infected apple trees were treated at least two or three times with 31.25 and 62.5 ml/l available chlorine content in NaOCl, it greatly increased the rooting of rootstock, and restored the tree crown density by 44.4-60.5%. In addition, the number of commercial fruit setting was increased by 54.3-64.5%, and the total starch content in shoots was significantly higher than other non-treated apple trees. However, the untreated disease control and thiophanate-methyl WP treated trees showed the symptom of dieback. Therefore, our results indicate that the drenching treatment of NaOCl with 31.25-62.5 ml/l available chlorine content more than two times from late fall to early spring could effectively control the violet root rot and recover tree vigor up to 60%.