Up to now, there is no remedy against the devastating maize disease, which threatens Kenya’s staple food. Maize, Kenya’s main staple food crop is now facing an uncertain future following a fast spreading maize disease that threatens its production across the country. The maize disease, now identified as Maize Lethal Necrotic (MLN) disease is caused by a combination of viruses was first reported in lower Longisa division of Bomet district in September last year. Later it spread to the neighbouring districts of Sotik, Konoin, Chepalungu, Transmara, Kisii, Bureti and Kericho. The disease has now moved to other parts of the country where it has attacked the maize crops in Nakuru, Naivasha, Rumuruti, Imenti south, Embu and Kibwezi. Farmers in other maize growing in North Rift have also reported signs of the disease. Transmitted through seeds New scientific findings by KARI-NARL, the Ohio State University (USA) and FERA (UK) have established that the disease is caused by a combination of viruses, the main ones being the Maize Chlorotic Mottle Virus (MCMV), a virus that has not been reported in Kenya before and the Sugarcane Mosaic Virus (SCMV) which combine to cause the Maize Lethal Necrotic (MLN) disease. Researchers say the disease is transmitted through seeds and maize pests such as thrips, stemborer, rootworms, flea beetles and other insects. All varieties of maize planted in all above-mentioned regions are affected by the disease, which reduces the crop options for farmers. Research institutions have set up two trial sites in Naivasha and Bomet to test the resistance levels of different maize varieties to the disease. The disease has no cure. Stop the maize disease from spreading Crop rotation, field sanitation and pest control are good measures that can reduce the damage caused by maize disease. Maize plants infected by MLN disease start drying from the leaves downwards. When it was first reported last year and a diagnosis made by the Kenya Plant Health Inspection Service (KEPHIS) indicated a fungus, Cephalosporium acremonium, as being responsible for the disease. Many thought this was an isolated case of a disease that would soon be contained. Researchers have now discovered an additional number of viruses that are responsible for the disease now identified as Maize Lethal Necrosis (MLN) disease. But the rate at which the disease is spreading poses the greatest threat to maize production in the country. Just to demonstrate how devastating the new disease is: Farmers in Bomet, where it was first discovered in September last year, lost over 62,400 bags of maize valued at Ksh 218 million. More than 65 per cent of the maize crop planted in the Bomet district was destroyed by the disease. All maize varieties are affected; many farmers believe that only some varieties are susceptible to the disease. How to identify the maize disease • At knee height, the upper maize leaves start yellowing and later on start drying turning brown from the mid-rib towards the leaf margins. • The drying progresses to the lower maize leaves. • The stem and the nodes turn brown. • In some cases the maize produces many shoots (excessive tillering) • At the beginning it is only the upper leaves that appear brown • Towards maturity the cobs shrink and do not put in any grains. • In some cases the maize plants appear stunted. How farmers can control the disease The Maize Lethal Necrosis (MLN) disease has no cure. Once your maize crop has been affected by the disease, the only option left for the farmer is to cut, put it in a heap in an isolated part of the farm and burn it. Other measures farmers can take are outlined below: • Once your maize is affected you cannot plant another maize crop on the same field for the next two or three seasons to ensure the field is free of all the disease-causing pathogens and viruses. • Farmers in affected areas are advised to plant other crops such as sorghum, millet, Irish potatoes, sweet potatoes, cassava, beans, peas, bananas or any other crop apart from maize for two to three seasons. • Farmers are advised to do scouting in their maize farms for signs of the disease as indicated above. If they notice a maize plant with any of the symptoms, it should be uprooted, burnt or buried deep in the soil to stop the disease from spreading. • Use of clean certified seed is very important. Farmers using maize seed from unknown sources can easily introduce disease into their farms. • Regular spraying of the maize crop with pesticides and plant extracts is a good practice because pests such as aphids, stem-borer, maize beetles and thrips are the main vectors that transfer the disease from one area or farm to the next. • Ensure the maize field is clean and free of any weeds that act as hosts to some of the pests that transfer the disease to the maize. • Never plant maize that you have harvested as seed again as this will re-introduce the disease into your shamba and spread it. A cheap method to control pests in maize Controlling pests in maize at the growing stage is a very important measure in reducing damage to maize, which leads to loss in the overall yield at harvest. Some of the pests that are very common in maize at the early stages of growth include stemborers, aphids, chaffer grubs, bollworms, thrips and beetles. Instead of buying chemicals to control these pests, farmers can make their own pesticides at home using pepper and ash. Scientists have discovered that a mixture of ash and pepper is much more effective than using some of the chemicals that cost a lot of money. Farmers can buy pepper powder in the market if they do not grow it in their gardens. How to make an ash-pepper mixture • Buy ripe pepper or pick ripe ones from your own garden. • Dry the pepper and make a powder by either grinding or pounding, then remove the big particles • Sieve cold wood ash from the fireplace • Get 1 gorogoro (2kg tin) of ash from the fireplace. • Mix 1 gorogoro of ash with 5 teaspoonfuls of pepper powder. • Mix the pepper and ash properly. • Put the mixture in a used pesticide container that has small holes at the top. • Apply the mixture from the container by shaking it once into each plant funnel. If you do not have an insecticide container you can use your hands to apply. A pinch of the mixture applied to every plant is enough – but remember to wash your hands after application. Source: Dr. Margaret Mulaa, KARI, Kitale When to apply For good pest control with pepper and ash mixture follow the following guidelines: • Plant early at least 2 weeks before onset of the rains. • Look for pest damage every 3 days, starting from the second week after plants emerge in the lower drier areas, and 3-4 weeks in medium and high altitude areas like Trans-Nzoia and Uasin Gishu. • Apply the mixture after you see a few holes on the leaves. If you see more holes later, then apply the mixture again. more learning through sharing...
Posted on: Tue, 08 Oct 2013 12:02:01 +0000
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