Source: Nairobi Star [abridged, edited]
Maize farmers in Narok [County] are staring at losses in crop yields following the outbreak of head smut disease suspected to be linked with fake seeds. Most of the farmers claim to have bought 'genuine' seeds.
According to a large-scale maize farmer, his crop was lush in the initial stages up to the production stage when he realised that the cobs had been affected by head smut. "I did 168 acres [68 ha] of maize; in every 5 maize plants, 3 had head smuts," he said. "I purchased my seeds through a renowned agent, but from these yields, I doubt the seed quality."
[Another farmer] who owns a 10-acre [4 ha] maize farm, is also experiencing the same problem. "Last year  I harvested 22 90kg bags per acre, but this year  I will be lucky if I get 5 bags per acre," he said.
[Head smut caused by _Sporisorium reilianum_ (previously _Sphacelotheca reiliana_) can affect both maize and sorghum; each of 2 existing strains is restricted to one of the hosts. In maize, it infects the young seedling systemically, then grows through the plant without inducing symptoms, until it eventually reaches reproductive tissues (ears and/or tassels) replacing them with galls producing masses of black spores. Plants may be stunted, distortion is common, leafy structures may replace the plant's ears or flowering components (phyllody). Infection of the host occurs mainly during seed germination. Cool weather, dry seed bed conditions, and nitrogen deficiency favour the disease.
The fungus survives in the soil and can be seed borne. Spores can be spread by wind over long distances and mechanical means (such as on contaminated materials or tools). Disease management may include cultural techniques (such as long crop rotation), phytosanitary measures, and the use of disease-free seed. Some resistant crop varieties are available.
Although the claim above that contaminated seed is the cause of the outbreak is plausible, the previous cultivation or head smut history of the affected fields is not clarified. Therefore, presence of the fungus in the soil from previous maize crops or infections due to wind borne spores from other areas cannot be excluded.
Head smut symptoms on maize:
Head smut on sorghum:
Photo gallery of symptoms on both hosts:
Head smut information:
Head smut disease cycle:
_S. reilianum_ taxonomy and synonyms: