• Research in Plant Disease
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• v.16 no.2
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• pp.148-152
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• 2010

To establish the efficient screening method for resistance of radish to F. oxysporum f. sp. raphani, we investigated the development of Fusarium wilt of two radish cultivars, 'Songbaek' (susceptible) and 'Tokwang' (moderately resistant), according to several conditions such as inoculation methods, inoculum concentrations, and dipping periods of radish roots in spore suspension. By infected soil and soil-drenching inoculation methods, Fusarium wilt did not occur on the seedlings of both cultivars. In root dipping inoculation method using cut or non-cut roots of radish plants, the cut roots were easily infected by the pathogen than non-cut roots. And the disease development of two cultivars represented significant difference in non-cut root method. On the other hand, disease severity of Fusarium wilt on radish seedlings according to inoculum concentration increased in a dose-dependant manner, regardless of dipping periods. Using screening method established from the results, the 41 commercial radish cultivars were evaluated the degree of resistance to F. oxysporum f. sp. raphani. Among them, 6 radish cultivars were resistant, 22 cultivars were moderately resistant, and 13 cultivars were susceptible to Fusarium wilt.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.110-116
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• 2013

This study was carried out to establish the simple mass-screening methods for resistant tomato to Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL). Root dip inoculation method has been used in many studies on the resistance of tomato to disease. On the other hand, in mass-screening for resistant tomato to Fusarium wilt, the inoculation method is time-consuming and laborious procedure. Disease development of two FOL isolates on two cultivars of tomato according to inoculation method including root dip, tip and scalpel methods were investigated. In compatible interaction, tomato seedlings of each cultivar inoculated by tip method showed the lower and more variable disease severities than by root dip method. Whereas the seedlings by scalpel method represented clear resistant and susceptible responses to Fusarium wilt as root dip method. The resistance degree of each cultivar inoculated with FOL isolates by scalpel method was hardly affected by the tested incubation temperature and inoculum concentration. On the basis of the results, we suggest scalpel inoculation method as an efficient mass-screening method for resistant of tomato cultivars to Fusarium wilt. Roots of tomato seedlings at two-leaf stage grown in plastic cell tray were injured with scalpel and then spore suspension (more than $1{\times}10^7\;conidia{\cdot}mL^{-1}$) of FOL was poured directly on the roots. The infected plants were cultivated in a growth room at $25-30^{\circ}C$ for 4 weeks with 12-hours light a day.

• Research in Plant Disease
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• v.17 no.1
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• pp.13-18
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• 2011

This study was conducted to establish the efficient screening method for resistant cabbage to Fusarium wilt caused by Fusarium oxysporum f. sp. conglutinans. The resistance degrees of nine commercial cabbage cultivars to the disease were evaluated. Among them, five cultivars (YR-honam, Ogane, Greenhot, Redmat, and Ccoccoma) showing different resistance to the fungus were selected. Then development of Fusarium wilt of the cultivars according to several conditions including root wounding, dipping period of roots in spore suspension, inoculum concentration, and incubation temperature to develop the disease was investigated. Highly resistant cultivars such as 'YR-honam' and 'Ogane' hardly showed change of resistance to the disease by root wounding, dipping period, and inoculum concentration, while disease severity of Fusarium wilt on the cultivars was changed with incubation temperatures ($20^{\circ}C$, $25^{\circ}C$ and $30^{\circ}C$). When the cabbage cultivars were incubated at $25^{\circ}C$, they represented the most difference of resistance and susceptibility to Fusarium wilt. From above results, we suggest that an efficient screening method for resistant cabbage to F. oxysporum f. sp. conglutinans is to dip the non-cut roots of 14-day-old seedlings in spore suspension of $1{\times}10^7$ conidia/ml for 0.5 hr and to transplant the seedlings to plastic pots with a fertilized soil, and then to cultivate the plants in a growth chamber at $25^{\circ}C$ for 3 weeks to develop Fusarium wilt.

• Research in Plant Disease
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• v.24 no.4
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• pp.257-264
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• 2018

Hydroponic strawberry culture system is increasing annually. Most of strawberry farmers use mulched bed in hydroponic culture and strawberry plants were transplanted in early September. After transplanting, Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae and twospotted spider mite (TSSM), Tetranychus urticae, can increase their occurrence under high temperature condition. Therefore, we conducted for comparison occurrence of Fusarium wilt and TSSM on mulched with green polyethylene film and non-mulched bed. Occurrence of Fusarium wilt on mulched bed was started from early October and more increase than non-mulched bed. Damage rate of TSSM on mulched bed was shown higher than non-mulched bed. Temperature of substrate in mulched bed increased than non-mulched bed, but relative humidity near plants was decreased. As a result, use of non-mulched bed should be effective for reducing of Fusarium wilt and TSSM on strawberry plants.

• Research in Plant Disease
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• v.24 no.1
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• pp.26-32
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• 2018

Fusarium wilt on strawberry plants caused by Fusarium oxysporum f. sp. fragariae (Fof) is a major disease in Korea. The prevalence of this disease is increasing, especially in hydroponic cultivation in strawberry field. This study assessed the effect of nutrition solution pH and electrical conductivity (EC) on Fusarium wilt in vitro and in field trials. pH levels of 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5 were assayed in vitro and in field trials. EC levels at 0, 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$ were assayed in field trials. Mycelial growth of Fof increased with increasing pH and was highest at $25^{\circ}C$ pH 7 and lowest at $20^{\circ}C$, pH 5.0 in vitro. The incidence of Fusarium wilt was lowest in the pH 6.5 treatment and highest in the pH 5 treatment in field trials. At higher pH levels, the EC decreased in the drain solution and the potassium content of strawberry leaves increased. In the EC assay, the severity of Fusarium wilt and nitrogen content of leaves increased as the EC increased. These results indicate that Fusarium wilt is related to pH and EC in hydroponic culture of strawberry plants.

• Research in Plant Disease
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• v.11 no.1
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• pp.35-38
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• 2005

The occurrence of Fusarium wilt in strawberry fields in Korea was assessed from 2001 to 2003. Fusarium wilt was found from June to August in nursery beds, from September to October after planting in production beds, and from January to March during harvesting period. The symptoms were root rots, discolored vascular tissue in the crown and deformation and yellowing of central leaflets. The disease occurred in up to 30% of plants in 37 of 214 fields surveyed. Fusarium wilt occurred from cvs. ‘Dochiodome’, ‘Maehyang’, ‘Redpearl’, ‘Samaberry ’ and ‘Akihime’ and more severe from cvs. ‘Samaberry’, ‘Maehyang’ and ‘Dochiodome’. Infested soils had high salt concentrations, high nitrogen, phosphate concentrations and low pH. The results of pathogenicity test showed that Fo47 and Fo79 isolated from cvs. ‘Dochiodome’ and ‘Samaberry’ were strong pathogenic to all of four cultivars, and ‘Dochiodome’, ‘Redpearl’, ‘Maehyang’ were relatively susceptible to the all isolates.

• Horticultural Science & Technology
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• v.29 no.1
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• pp.48-52
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• 2011

This study was conducted to establish the efficient screening system for resistant radish to Fusarium oxysporum f. sp. raphani. Five radish cultivars ('Myoungsan', 'Chungdu', 'Jangsaeng', 'Hannongyeorm', and 'Chungsukungjung') showing different degree of resistance to the fungus were selected. And the development of Fusarium wilt of the cultivars according to several conditions such as root wounding, dipping period of roots in spore suspension, inoculum concentration, and incubation temperature to develop the disease was tested. In distinguishing the resistance degree of the radish cultivars to the disease, non-cut roots were more effective than cut roots. And occurrence of Fusarium wilt of the radish plants increased in the proportion to increase of root-dipping period and spore concentration of the fungus. Thus, optimum conditions to differentiate susceptible and resistant cultivars to the disease were root-dipping period of 0.5 hour and spore concentration of $1{\times}10^7\;conidia{\cdot}mL^{-1}$. Disease severity of Fusarium wilt on the cultivars was changed with incubation temperature and the radish seedlings incubated at $25^{\circ}C$ represented the most difference of resistance and susceptibility to Fusarium wilt. From the above results, we suggest that the efficient screening method for resistant radish to Fusarium oxysporum f. sp. raphani would be to dip non-cut roots of fourteen-day-old radish seedlings in spore suspension of $1{\times}10^7\;conidia{\cdot}mL^{-1}$ for 0.5 hour and to transplant the inoculated plants to plastic pots with fertilized soil, and then to incubate the radish plants at a temperature of $25^{\circ}C$ for development of Fusarium wilt.

• Research in Plant Disease
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• v.9 no.2
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• pp.79-84
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• 2003

A wilt disease of commercial cyclamen (Cyclamen persicum) which grown in greenhouse was found in Gyeo-nggi province of Korea during the period from August, 2001 to July, 2002. The disease incidence was up to 42.7% in Kimpo, Gyeonggi province. The disease was more severe in ebb and flow irrigation system than con-ventional overhead flooding\'s. The wilted cyclamen plants showed the chlorosis of leaves and followed by the death. The vascular tissues of the infected basal stem and bulb were discolored with black streaks. The casual fungus was identified to be Fusarium oxysporum f. sp. cyclaminis on the basis of mycological characteristics. Effect of infected soil showed 100% infection rate when the cyclamen plants were grown in potting with infested soil. Examine resistant cultivar showed ‘Matis red’, ‘Schubert’, ‘Victoria’ and ‘Chopin’ were the resistant cultivars but most of cultivars were susceptible to Fusarium wilt. The control effect of chemicals for cyclamen wilt was not much efficient to curative effects even though. Benomyl WP and Fludioxonil SC on the Fusarium wilt had only preventive effects by soil drenching in the pot before inoculation of F. oxysporum. This is the first report on the fusarium wilt of cyclamen caused by F. oxysporum f. sp. cyclaminis in Korea.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.129-132
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• 2014

A new resistant cabbage variety 'CT-171' to Fusarium wilt was bred by crossing $A337MSBC_5$ with resistance to the disease and 397-$G_6$ with good density and color. 'CT-171' was selected after combining ability, seed gathering and regional adaptability test in 2008. For breeding of resistant varieties, we investigated the development of Fusarium wilt on cabbage seedlings inoculated with Fusariumoxysporum f. sp. conglutinans by root dipping inoculation method. As a result, 'CT-171' showed higher resistance to Fusarium wilt than 'Asiaball' used as control. The maturity of new variety was 58 days and was faster than control and well suited for autumn cultivation because of cold resistance. The anthocyanin pigment of plant was not revealed. The weight, height and width of head were 1.5 kg, 14 cm and 15 cm, respectively and the core size was 5.7 cm and stable in various cultivation environments. 'CT-171' which showed good agricultural character and resistance to Fusarium wilt filed for variety protect right in Korea Seed & Variety Service on February 2013. The new variety will be appropriate for export and domestic consumption.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.273-277
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• 2011

Fusarium oxysporum f. sp. fragariae (Fof), the causal agent of crown and root rot in strawberry, is the most serious soilborne disease of nursery plants in Korea. The possibility of infection by Fof through runner propagation from infected mother plants of strawberry cv. 'Kumhyang' was assessed in stolons and daughter plants hanging from raised beds. The number of daughter plants from an infected mother plant in plastic house and photosynthetic photon flux (PPF) system, 280 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was 2.7 and 3.8 plants after 58 days, respectively. However, healthy mother plants produced 6.5 and 8.4 daughter plants, respectively. The pathogen was detected in the uppermost portion of the stolon after 58 days, but was not detected further down the stolon. After 90 days, it was detected in all portions of the stolon between mother and $1^{st}$ daughter plant and in 60% of all $1^{st}$ daughter plants. The pathogen was not detected in the corresponding portions of the non-infected controls. These results show that infected mother plants can transmit Fof to their daughter plants without passing through the soil and $1^{st}$ daughter was used as mother plant in PPF system for propagating healthy plants.