Diseases

Gibberella zeae (Schwein.)Petch., G. fujikuroi (Sawada) Ito in Ito &.Kimura - Gibberella Stalk Rot.

Systematic position.

Kindom Fungi, division Ascomycota, class Ascomycetes, sub-class Sordariomycetidae, oder Hypocreales, family Nectriaceae.
Synonymy G. zeae : Botryosphaeria saubinetii (Mont.) Niessl, Dichomera saubinetii (Mont.) Cooke, Dothidea zeae (Schwein.) Schwein., Fusarium graminearum Schwabe, F. roseum Link, Gibbera saubinetii Mont., Gibberella roseum (Link) W.C. Snyder & H.N. Hansen, Gibberella saubinetii (Mont.) Sacc., Sphaeria saubinetii Berk. & Broome, S. zeae Schwein.
G. fujikuroi: Gibberella fujikuroi var. moniliformis (Wineland) Kuhlman. (http://www.indexfungorum.org)

Biological group.

Hemibiotroph.

Morphology and biology.

Initially the rot causes a dark external lesion at the lower parts of stalks and at nodes, and can extend to wilting and death. The pith of maize is shredded, having pink discoloration. Gibberella fungi produce small black perithecia in plant tissue. Perithecia of Gibberella are globular, black-blue, 150-300 x 100-250 um in size. Sacs located inside
perithecia contain 8 uncolored oval ascospores with 1-3 walls, 20-30 x 3-5 um in size. Fungi over winter in corn debris left on the soil surface. Ascospores are produced during wet spring weather and infect tissue. During summer conidia are formed on damaged tissue and inoculate new plants (leaves, nodes). Infection can be seed borne and can spread through damaged roots.

Ecology.

Severity of disease is significantly higher when weather is warm and moist during the maize maturity period.

Distribution.

The disease occurs in most areas where maize is grown. The distribution of Stalk Rot is high in regions with wet and moderate climates. Under dry conditions this disease occurs rarely (Borovskaya & Matichuk, 1990); (Ivashchenko, 1989, 1991); Florya, 1979).

Economic significance.

The visual symptoms of Stalk Rot become apparent after silking. But infection of plants begins during early periods of growth and strongly influences nutritional uptake of plant. Damaged plants produce undersized seed that lead to a quantitative reduction of yield. Mass of 1000 seeds decreases by 12.6 to 28.5%. Every 10% increase of disease severity
increases stalk breaking by 1-6.4%. The disease can result in premature death of diseased plants. Measures that can overcome disease development include: seed treatment with fungicides; corn crop rotation; sowing seeds in well-prepared soil, balanced soil fertility, and using resistant hybrids of maize.

Reference citations:

Borovskaya M.F. Matichuk V.G. 1990. Diseases of maize. Kishinev: Shtiintsa. 132-138 pp. (In Russian)
Florya M.B. 1979. Stalk Rots on maize. Selection and Genetics of Maize. Krasnodar. 122-133 pp. (In Russian)
Ivashchenko V.G. 1989. Methods of estimation and harmful forecast of Stalk Rots in corn. Leningrad: Pushkin. 18 pp. (In Russian)
Ivashchenko V.G. 1991. Fungal diseases of stalk and leaves of maize under different ecological and geographical conditions. Mikologiya i fitopatologiya 25(5): 432-437. (In Russian)
Ivashchenko V.G., Varenik B.Ph., Sokolov V.M. 1990. Harmfulness of Stalk Rots on maize in South Ukraine. Selektsiya i semenovodstvo 5: 19-22. (In Russian)
Susidko P.I., Gritsenko G.V., Nemlienko F.E. 1975. Integrated system of protection measures for maize against pests, diseases and weeds. Moscow: Kolos. 47 pp. (In Russian)

© Gagkaeva T.Yu.