Paper Count: 4 Fusarium oxysporum f. Lakhdari , A. Dahliz , Y. Bouchikh , R. Hammi , A. Soud , A.
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The fungus was first reported in Japan in It is one of the most destructive diseases of tomatoes 1, 2, 3. There is no distinguished physiological race of FORL. However, nine Vegetative Compatibility Groups VCGs have been identified, which indicates it has a high genetic diversity. There is no known teleomorph 4.
Symptoms and Signs In general, symptoms include yellowing, wilting, stunted growth, and discolored internal stem tissue. The oldest leaves first begin to yellow while the fruit is reaching maturity. Eventually those yellow leaves turn brown. During the warmest times of the day, infected plants wilt and then recover at night.
Sometimes, adventitious roots may occur above the infected parts. Severe infections can cause root damage, rapid wilting, and death. Plants can survive less severe infections through the growing season, but the fruit is often pale 2, 3. Signs include yellow to orange or pinkish masses of macroconidia on lower stems and stem lesions.
This is the asexual sporulation layer of the pathogen 2, 3. Ecology and Spread FORL is widespread and leads to substantial yield losses in both greenhouse and soil production systems. The pathogen is disseminated via infected seeds, plant material, and soil compost. Fungus gnats have been reported as vectors of the fungus. Readily spread conidia in water sources provide another way of pathogen dissemination, especially in irrigation and hydroponic cultivation system.
Microconidia have been detected for airborne dispersal. The fungus enters through wounds or natural opening caused by secondary roots, and then colonizes the cortical tissue. At this phase, brown lesions are formed. In vascular tissues, the fungus can spread up to 25 cm. The optimum conditions for disease development is F, low substrate pH, and soggy and ammoniacal soil 1, 2, 3. Once the root system is infected by this pathogen, the root system will be reduced.
While the temperature increases, water demand increases dramatically which leads to plant wilt or death 4. Geographic Distribution Crown and root rot of tomatoes is a widely distributed disease in Western Europe, North America, the Mediterranean region, and Japan 1, 2, 3. Management Avoid ammoniacal nitrogen and maintain soil pH between 6 to 7. Rotate with a nonsusceptible crop. Sterilize or discard used wooden tomato stakes. Plant resistant cultivars.
Start transplants with disease free seeds and inspect transplants in the greenhouse frequently, roguing any plants that appear weak.
Fumigate fields as a preventive measure. No fungicides are effective to control this pathogen. Do not save seeds from infected fields. Till fields in the fall to bury crop residue. Consult your local extension specialist for legal and efficacious fungicide products available in your state. Remember, the label is the law and the product applicator is responsible for reading and following all chemical labeling 1, 2, 3. For lab diagnostic: Isolate spores from leaf, stem and roots.
This fungus can only be isolated near to the lesion since it does not widely spread into asymptomatic host tissue. Incubate plant material to allow production of spores. Diagnostic features: It produces three types of spores: macroconidia, microconidia, and chlamydospores. Macroconidia are three to four septate with curved apical cell and a foot-shaped basal cell. Microconidia are unicellular, oval, elliptical, or reinform in shape. Single spore technique can be found on Bugwoodwiki. However the disadvange is that it can be only good to species level 5.
Paulus, A. Fusarium Crown and Root Rot, pp. Jones, J. Jones, R. Stall and T. Zitter ed. American Phytopathological Society Press, St.
Paul, MN. Roberts, P. Disease management: Fusarium crown and root rot on tomato. Zhang, S, P. Roberts, R. McGovern, and L. Fusarium crown and root rot of tomato in Florida. Katan, T, D. Zamir, Matti Sarfatti, and J. Vegetative Compatibility Groups and Subgroups in Fusarium oxysporum f.
Genetics 81 3 : Windels, C. Singleton, J. Mihail, and C. Methods for research on soilborne phytopathogenic fungi.
Snyder and H. Hans, a soilborne plant pathogen in the class Hyphomycetes, causes Fusarium wilt specifically in tomato. This disease was first described by G. Massee in England in It is of worldwide importance where at least 32 countries had reported the disease, which is particularly severe in countries with warm climate. At one time, the disease nearly destroyed tomato production in parts of Florida and the southeastern states of United States. However, the development and use of resistant cultivars have nearly eliminate the concern over this disease.
Fusarium oxysporum f. sp. radicis-lycopersici
Received Jul 29; Accepted Feb This article has been cited by other articles in PMC. Abstract Background Fusarium oxysporum f. Despite such major economic impact, little is known about the molecular mechanisms regulating Fusarium oxysporum f.
Fusarium oxysporum f. sp. radicis-lycopersici Related Abstracts
Received Jun 22; Accepted Sep 7. This article has been cited by other articles in PMC. Abstract Benzo- 1,2,3 -thiadiazolecarbothioic acid S-methyl ester BTH , a synthetic chemical, was applied as a foliar spray to tomato Lycopersicon esculentum plants and evaluated for its potential to confer increased resistance against the soil-borne pathogen Fusarium oxysporum f. In nontreated tomato plants all root tissues were massively colonized by FORL hyphae. Pathogen ingress toward the vascular stele was accompanied by severe host cell alterations, including cell wall breakdown. In BTH-treated plants striking differences in the rate and extent of fungal colonization were observed.