Sorghum
Covered Kernel Smut of Sorghum
Sporisorium sorghi
Fungus
In a Nutshell
- Several grains per ear replaced by conical or oval shaped structures.
- Whitish to gray or brown colored, sometimes with stripes.
Can also be found in
Sorghum
Symptoms
Sorghum grains are replaced by conical or oval shaped spore-producing structures, called smut sori. These organs are covered by a persistent coat, and depending on their size, can be covered by glumes to a length of more than 1 cm. The glumes appear normal in color. Most sori are conical or oval-shaped and look like an elongated sorghum seed. Sori are whitish to gray or brown, sometimes overlaid with stripes. In most cases, heads are only partially smutted. In some cases, the panicle branches may be completely destroyed, leaving only the distorted central stem structure covered with sori.
Recommendations
Organic Control
No biological treatment seems to be available at the moment to treat this disease. Contact us in case you know of any.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Seed treatment with carboxin (2g / 1kg of seeds) is recommended to suppress a disease outbreak. Foliar sprays containing propiconazole, maneb or mancozeb also showed satisfying results in field studies.
What caused it?
When a smut-infested kernel is planted, resting spores germinate along with the seed, developing within the seedling and producing spores that will worsen the infectious process. These spores are carried by the wind to other plants, where they germinate and produce fungal growth that spread systemically within the plant, apparently without damaging it. The first symptoms appear fist during the formation of flowers (heading). At that time, the fungal structures gradually replace the kernels and a membrane grows around them . At maturity, this membrane ruptures releasing the new spores that will contaminate other seeds or the soil. The optimum temperature for spore germination and infection of the plant is 30 °C.
Preventive Measures
- Plant resistant or tolerant varieties, if available.
- Planting seeds in soil at temperatures between 15°C and 32°C prevents the fungus of germinating.
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