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International Journal of Microbiology
Volume 2018, Article ID 4568520, 10 pages
Research Article

Morphological and Molecular Identification of the Causal Agent of Anthracnose Disease of Avocado in Kenya

1Department of Plant Sciences, Kenyatta University, P.O. Box 43844, Nairobi, Kenya
2Department of Microbiology, Kenyatta University, P.O. Box 43844, Nairobi, Kenya
3Kenya Agricultural and Livestock Research Organisation, P.O. Box 220, Thika, Kenya
4Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, Nairobi, Kenya

Correspondence should be addressed to S. K. Kimaru; moc.liamg@1uramiks

Received 1 November 2017; Revised 25 January 2018; Accepted 31 January 2018; Published 27 February 2018

Academic Editor: Pierre Roques

Copyright © 2018 S. K. Kimaru et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Anthracnose disease of avocado contributes to a huge loss of avocado fruits due to postharvest rot in Kenya. The causal agent of this disease has not been clear but presumed to be Colletotrichum gloeosporioides as reported in other regions where avocado is grown. The fungus mainly infects fruits causing symptoms such as small blackish spots, “pepper spots,” and black spots with raised margin which coalesce as infection progresses. Due to economic losses associated with the disease and emerging information of other species of fungi as causal agents of the disease, this study was aimed at identifying causal agent(s) of the disease. A total of 80 fungal isolates were collected from diseased avocado fruits in Murang’a County, the main avocado growing region in Kenya. Forty-six isolates were morphologically identified as Colletotrichum spp. based on their cultural characteristics, mainly whitish, greyish, and creamish colour and cottony/velvety mycelia on the top side of the culture and greyish cream with concentric zonation on the reverse side. Their spores were straight with rounded end and nonseptate. Thirty-four isolates were identified as Pestalotiopsis spp. based on their cultural characteristics: whitish grey mycelium with black fruiting structure on the upper side and greyish black one on the lower side and septate spores with 3-4 septa and 2 or 3 appendages at one end. Further molecular studies using ITS indicated Colletotrichum gloeosporioides, Colletotrichum boninense, and Pestalotiopsis microspora as the causal agents of anthracnose disease in avocado. However, with this being the first report, there is a need to conduct further studies to establish whether there is coinfection or any interaction thereof.