Scientists have raised concerns over the outbreak of head smut maize disease.
The disease has been reported by maize farmers in parts of Kiambu county and Njoro in Nakuru county.
Wambui Kimani, from Juja in Kiambu county is a frustrated farmer because her maize crop has been affected by the disease.
“At first I did not know what had affected the crops because I have also been struggling with the fall armyworm," she told the Star.
"Last month, I was invited to a meeting on agriculture biotechnology and I decided to carry a sample of the affected maize to seek help. A scientist identified it as the smut disease and he advised me on what to do,” she said.
Kimani said even the chickens have refused to feed on the affected maize.
She is now counting losses, saying almost a quarter of the maize she has planted on her two acres’ land have been affected.
“I have tried to use pesticides and ash but nothing has worked. We need all the help we can get as farmers are losing a lot of money to pests and diseases,” Kimani said.
James Karanja, a maize breeder from the Kenya Agriculture and Livestock Research Organisation (KALRO), said the disease is caused by the fungus ustilago maydis.
The infection starts in the soil and the fungus grows through the plant during the season.
The head smut disease affects maize, sorghum and grasses and can cause yield losses of between 60-80 per cent.
Karanja said the disease is prevalent in the fields where the soil is infected. The seed will then act as a carrier once a farmer plants and this eventually spreads to the whole plant.
According to data from CABI on key pests and diseases in maize, head smut infects tassels, ears, and occasionally leaves. It can spread via wind and can survive for years in the soil.
The fungus lives on the maize ear, causing black masses to form there. It penetrates and develops inside the plant, but does not appear until flowering or cob formation. The black masses contain spores, or fungal seeds, that contaminate other plants.
“The grains of plants infected with head smut maintain their size but become dark and deformed. As a result, maize quality and yield decrease,” CABI said.
Karanja advised farmers to uproot the affected crop and bury it deep into the ground. It should be uprooted when the black masses which look like dust start showing in the plant.
“Do not feed the affected maize to the animals because it will get to the manure. Once you take the manure back to the fields, you will be multiplying and hence the spread of the disease. You will be adding the inoculum to your farm,” he said.
A report on the smut disease as an increasing threat to maize production in Kenya shows that maize smut occurs globally where maize is grown.
The report published in Kenyatta University Institutional Repository indicated that the disease reduces yields drastically through stunting and formation of galls on the above ground parts of the plant, especially on the developing cob and the tassel.
In the recent past there have been increased incidence of head smut disease in parts of Central Kenya where maize is the staple diet.
The report noted that infection usually becomes apparent when grain filling starts when it is often late to commence intervention measures.
“Observations indicate that most of the maize varieties grown in these regions are susceptible to infection with incidence reaching up to 50 per cent in many farms. Infection appears to be exacerbated by the close integration of maize farming and dairy animal production through the zero grazing system in the region,” the KU report said.
“The use of infected maize residues as fodder increases disease spread since pathogen spores pass through animal gut undamaged and are returned to the farm in manure, thus serving as sources of primary inoculum for maize crops in the following season,” said the report.
In addition, the pathogen also infects napier grass, which is also widely grown for fodder in the region.
Napier not only provides an alternate host for this pathogen but also plays a key role in the continuity of the pathogen cycle.
The report recommended that intervention should consider raising farmer awareness on the management measures. This includes regular scouting and timely removal of the smut galls before they break open and release the spores.
“Studies are needed to determine the extent of loss being incurred by farmers; to characterise the linkage between dairy farming and smut spread, and to identify resistant maize varieties,” the report indicated.