Spatial distribution model of phragmanthera plant parasite in Rift Valley Ecoregion of Kenya
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About 80% of Kenya’s land area has been classified as Arid and Semi-Arid, ASALs and experiences high temperatures and low erratic rainfall throughout the year. In the search for suitable tree species for agroforestry and landscape restoration in Kenyan ASALs two Meliaceae tree species, indigenous Melia volkensii (Geurke) and exotic Azadirachta indica (A. Juss.) were selected for further research. In Kenya, Botryosphaeriaceae has been reported on Grevillea robusta on-farm causing damage to the tree and in severe cases leads to mortality. Molecular identification of cultures used in the study based on rDNA of the ITS and Tef1-alpha gene regions for 86 isolates classified into 6 species of the Botryosphaeriaceae. 3 of the Botryosphaeriaceae species belonged to the genus Lasiodiplodia namely L. pseudotheobromae, L. theobromae and L. parva. This is the first report of species Spencermartinsia viticola and Macrophoma theicola in Kenya. Pathogenicity tests done under glasshouse conditions showed that the L. pseudotheobromae species was most virulent to both M. volkensii & A. indica while L. theobromae was least virulent to both tree species. Wilting & necrosis was recorded within 7 days of inoculation but wound healing occurred on both species after 12 weeks. This study gives insight into disease resistance and tolerance of these dryland species for plantation establishment. It also revealed wider host diversity for Botryosphaeriaceae in the drylands. Further research into the species disease resistance mechanisms and proper silvicultural treatments are a prerequisite for large scale planting of the two tree species in light of climate variation and ecosystem changes. The recommendations given in the study are being taken into account for commercial forestry ventures in the drylands and advisory services being provided for diseases control and management.
Key words: Pathogenicity test, Phylogenetic analyses, Lesion measurement
ID: 3623720