Maize Lethal Necrotic Disease (MLND)

.0 INTRODUCTION
1.1 Background information Maize Lethal Necrotic Disease (MLND) is a devastating disease that affects Maize (Zea Mays L.) and can cause up to 100% yield loss. In Kenya it was first reported in the year 2011 in lower elevations of Longisa division of Bomet County in South-Rift (Wangai et al., 2012). By then the disease had not been confirmed to be Maize lethal Necrosis (MLN). The maize crops in the areas showed symptoms of viral infection of chlorotic mottles on leaves developing on the top whorls of the plant. MLN was found to be caused by a double infection of two viruses’ i.e. Maize Chlorotic Mottle Virus (MCMV) and sugarcane mosaic virus (SCMV). MCMV belongs in the genus Machlomovirus and family of Tombusvirus (Li et al.,

This is caused by low soil fertility management, poor plant nutrition, timing of planting dates so that the crop is affected by drought and majorly failure to control pests (some are vectors) due to economic or financial reasons. Some small scale farmers also replant the harvested grains that may have been affected by the viruses hence increasing disease prevalence.
Some of the methods that can be used to control the spread of the disease include control of vectors, observing a closed season, uprooting affected plants from the field and burning them. Field hygiene and early planting are also important factors that should be considered. The most ideal method of control would be to breed or screen for a variety that is tolerant or resistant to MLND. This study should culminate to recommendations of spray regimes that can be used to control vector transmission of MLN viruses.
1.3

This is because viruses always utilize the metabolic processes of the host cell organisms in their replication. Upon infection the viral genomes combine with the genome of the host cell organism and the virus changes totally the functioning of the cell to the replication of the viral particles. The viral particles then infect the adjacent cells by moving through the plasmodesmata. In the new cell, the viral particles recombine to form complete viruses for infection of the new cell and replication. The problems encountered in the control of the disease call for research on other novel ways of managing the disease. This includes among other targeting the vectors of the disease as a way of controlling the disease. The MCMV is transmitted by corn thrips, leaf beetles or rootworms. The SCMV is transmitted by aphids. By targeting these insects the disease can be controlled. This study is intended to determine the number of sprays of biopesticide and the types of biopesticides that can be able to manage the disease spread. The reduction of disease incidence and severity by use of seed treatment will also be assessed. The losses caused by the disease might also be reduced due to a good spraying regime with effective