Fusarium oxysporum Schlecht, F. solani (Mart.) Appel et Wr., F. gibbosum App. et Wr., F. avenaceum (Fr.) Sacc., F. culmorum (Sm.) Sacc., F. heterosporium Nees. - Fusarium Seedling Root Rot, Fusarium Wilt of Soybean

Systematic position.

Class Deuteromycetes, superorder Hyphomycetales, order Moniliales, family Tuberculariaceae, genus Fusarium.

Biological group.


Morphology and biology.

Sources of the infection are infected ground, seeds, and vegetation residues. There are several types of fusariosis symptoms: root decay, destruction of growth point, withering, spots on leaves, rotting of beans and seeds. The disease shows as browning root neck and root on shoots. Deep brown ulcers appear on cotyledons, becoming covered with white-pink fungal sporification under damp weather conditions. Shoots often perish, if the point of growth is affected. Root decays on adult plants are characterized by thinned and brownish root neck that results in stem break and root rot. Small, later enlarging spots appear on leaves, the rest part of a leaf turns yellow and dries up. Tracheomycotic withering (the agent is F. oxysporum) is observed mainly in stages of flowering and beans formation; leaves lose turgor, turn yellow, then all plant dries up. Brownish tissues are appreciable on transverse section of a stem. Fusariosis results in abscission of flowers and ovaries. It is shown on beans at the end of vegetation as spots and ulcers. Mycelial pellicle penetrating into seeds is formed on valve walls. The infected seeds become wrinkled and weak. The fungus forms sporification on affected plants during vegetation season; there are numerous conidia of two types, small ones, or microconidia, and large ones, or macroconidia. Microconidia are oval, ovoid, clavate; macroconidia are more often crescent, fusiform, lanceolate, 3-5-septate. Macroconidia are 20-60 x 3-6 mkm in size. The fungus also forms chlamydospores that are glabrous or rough, brown or unpainted.


The disease meets everywhere on soya crops.


The minimal temperature for germination of spores of fusariosis agents is 4.C, optimum one for their growth is 20-25.C. Root decays prevail at sufficient and excessive humidifying. The severe infection of root system of plants occurs at soil humidity 70%. Tracheomycotic withering develops under dry and hot weather conditions.

Economic significance.

Agents of fusariosis are not specialized, affecting many species of plants of various families. The disease is very harmful. Its development on shoots brings plants to death. Diseased adult plants lag behind in growth, forming weak beans; or the beans are absolutely not set; the plants produce weak non-germinating seeds. The weight of grain of strongly affected plants may be reduced by 57-77%. Control measures are maintenance of crop rotation, autumn plowing, optimum terms of sowing, duly harvesting and drying of grain, seed dressing, chemical treatments of plants during vegetation, use of resistant varieties.

Related references:

Dubovitskaya L.K. 1987. Root Rot of Soybean in Primorskii Territory and its control. PhD Thesis. Leningrad: VIZR, 16 p.
Prostakova Zh.G., Ganya A.I. 1983. Fungal diseases of soybean and their control. Kishinev: Shtiintsa, 35 p.
Zaostrovnykh V.I., Dubovitskaya L.K. 2003. Harmful organisms of soya and system of phytosanitary optimization of its crops. Novosibirsk: Kemerovo SKHI, Dal.nevostochnyi GAU, 528 p. (in Russian).
Zhukovskaya S.A., Ovchinnikova A.M. 1980. Agents of fungal diseases of soybean. In: Azbukina Z.M., ed. Agents of diseases of agricultural plants in the Far East. Moscow: Nauka, p. 5-50

© Kungurtseva O.V.

Photo Kungurtseva O.V.

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