Seedling Blight of Sorghum

Seedling Blight of Sorghum

Many plants are susceptible to seedling blight and sorghum is no exception. Seedling blight can occur as a result from the effects of abiotic and /or biotic factors. Healthy seed growing under unfavorable environmental conditions may not perform well and die or suffer retarded development which ultimately results in yield reduction. When biotic factor are involved, seedling blight arises as a result of poor seed quality or infection by seed- or soil borne pathogens. The deleterious effects of seedling blight are generally seen when seed is attempting to germinate in cold (less than 18^oC), wet soil. Fungi may affect seed in the following ways:

Rhizopus and Aspergillus are common examples.
A fungus infecting other parts of the plant may also infect seed and may or may not influence seed quality. Effect on plant health may not be apparent until planting. An example is Colletotrichum graminicola (anthracnose).
Fungi specifically infect seed in the field prior to maturity and cause a reduction in quality. These fungi are referred to as grain molds. Two of the most common examples are Fusarium moniliforme and Curvularia lunata.
- after it matures and cause a reduction in quality. These fungi are referred to as weathering molds. Species of Fusarium, Aspergillus and Cladosporium behave in this manner.
Fungi may infect seed during storage under low moisture conditions. These fungi are referred to as storage fungi. Penicillium spp. and Aspergillus spp. are the most common members of this group.
Soil borne fungi may infect ungerminated seed and germinating seed growing under unfavorable conditions. Pythium spp. and Rhizoctonia spp. are most commonly associated with this situation. Fusarium spp. and Penicillium spp., which may also be seed borne can also be placed in this group.

Symptoms

Symptoms associated with seedling blight are seed rot, pre- and post-emergent damping-off and root and seedling rot. Pre-emergent damping-off occurs when seed germinates and rots below the soil line. Post-emergent damping-off occurs when cotyledons emerge from the soil before infection occurs. Chlorosis (yellowing), stunting or seedling death occurs at this time. Root and seedling rots are most commonly causes by infection by a Pythium spp. P. arrhenomanes and P. graminicola have both been associated with this type of injury. Root lesions that are reddish brown develop on infected plants. The entire root may eventually be affected and collapse. Infection can occur to varying degrees so a range of above ground symptoms may also be evident. Chlorosis and stunting are common.

Plant Health Management

Seed Treatment

Pythium

Fusarium

Rhizoctonia

Pythium).

Use high quality seed

Seed free of any physical injury or fungal growth.

Plant seed when soil temperature has reached its optimum for seed germination

References

Odvody, G.N. 1992. Biotic and abiotic factors associated with seedling diseases of sorghum Pages 161-166 in W.A.J. de Milliano, R.A. Frederiksen, and G.D. Bengston, eds. Sorghum and millets diseases: a second world review. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India.

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Caveat

This description is presented for information only and no endorsement is intended for products listed, nor criticism meant for products not mentioned. Always consult the product label before purchasing and using any pesticide.

Material contained on the Links from the page are the responsibility of the linked page's author(s).

This page was drafted by: Jane Christensen, Department of Plant Pathology, University of Nebraska-Lincoln

Disease images were provided by: Dr. David Wysong, Department of Plant Pathology, University of Nebraska-Lincoln

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This page is authored and maintained by:
Dr. J.E. Partridge, Department of Plant Pathology, University of Nebraska-Lincoln

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