Occurrence and Distribution of Potato Pests and Diseases in Kenya

Abstract

Potato plays an important role in food security in Kenya but yields are low (<10 t/ha), and this is partly attributed to the lack of healthy planting material. This study is the first wide-scale survey to determine the occurrence and distribution of common potato pests and diseases in Kenyan seed (certified and quality declared) and ware crops. Potato crops growing on 101 farms in 21 districts were examined. Approximately 36% of plants in farmers' fields sampled both during the long rains (main potato-growing season) and short rains seasons displayed virus-like disease symptoms. Six viruses (potato leafroll virus (PLRV), Potato virus A (PVA), potato virus M (PVM), potato virus S (PVS), potato virus X (PVX), and potato virus Y (PVY)) were detected using double antibody sandwich enzyme-linked immunosorbent assay in potato samples. Sequencing of polymerase chain reaction products from PVY-infected plants revealed the presence of recombinant strains of PVY (NTN and Wilga). Four aphid species, Macrosiphum euphorbiae, Aphis gossypii, Myzus persicae, and Aphis fabae, colonized potato in all districts, occurring in greater numbers west of the Great Rift Valley than to the east. There was a positive correlation between virus incidence and aphid numbers in the long rains (main) potato-growing season. PLRV, PVM, PVS, PVX, and PVY were detected in solanaceous weeds. Ralstonia solanacearum was Potato Research (2013) 56:325-342

Effectiveness of Positive Selection in Managing Seed-Borne Potato Viruses

“…Low incidences of PLVR, PVM and PVY as well as zero detection of PVA and PVX in RSS tuber samples may be attributed to restricted spread of these viruses due to the absence of insect vectors and alternate hosts in the experimental site (Djilani-Khouadja et al, 2010). Were et al (2013) also reported that PVS as the most detected virus followed by PVY, PVX, and PLRV in samples collected from potato growing districts in Kenya. Yardimci et al (2015) also reported that PVS and PVY as the most prevalent potato viruses in potato growing areas in Turkey when ELISA tests were conducted on tubers.…”

“…High incidences of PVS may have occurred due to its ability to pass through tissue culture process which is usually adopted in production of certified seeds (Were et al, 2013) or because PVS is mainly transmitted mechanically, it could have spread by farmers during farm operations (Gul et al, 2013). Low incidences of PLVR, PVM and PVY as well as zero detection of PVA and PVX in RSS tuber samples may be attributed to restricted spread of these viruses due to the absence of insect vectors and alternate hosts in the experimental site (Djilani-Khouadja et al, 2010).…”

“…Yield losses following virus infection is variety specific, and potato varieties react differently to the type of virus, its growth stage and infection type (Ali et al, 2013;Rahman et al, 2010). Six potato viruses namely Potato Leaf Roll Virus (PLRV), Potato Virus A (PVA), Potato Virus M (PVM), Potato Virus S (PVS), Potato Virus X (PVX), and Potato Virus Y (PVY) and four aphid vector species namely Macrosiphum euphorbiae, Aphis gossypii, Myzus persicae, and Aphis fabae are known to affect potato production in Kenya causing low yields (Were et al, 2013). Kenya produces an average of 7.7 t/ha of potatoes per season which is much less than the potential yield of 40-50 t/ha.…”

Seed Potato Production Practices and Quality of Farm Saved Seed Potato in Kiambu and Nyandarua Counties in Kenya

“…However, [45] reported that potato tuber moth to be the most lethal pest unlike cutworms as reported in this study. In addition, [46] reported potato aphids as the most lethal field pests especially in the spread of viral diseases. Cutworms were the most damaging field pest since they cause damage at planting leading to poor field establishment [19].…”

Belowground Influence of Rhizobium Inoculant and Water Hyacinth Composts on Yellow Bean Infested by Aphis fabae and Colletotrichum lindemuthianum under Field Conditions

“…Depletion of soil nutrients such as nitrogen and phosphorus has been a growing problem for bean production in East Africa (Kimani et al, 2007(Kimani et al, , 2008; Ayuke et al, 2011). Insect pests such as the black bean aphid Aphis fabae have been transmitting viral diseases (Beebe, 2012;Were et al, 2013), while fungal pathogens such as Colletotrichum lindemuthianum cause anthracnose disease of beans in East Africa (Beebe, 2012;Kharinda, 2013). These factors have been complicated by the fact that local cultivars that are widely grown by smallholder farmers in East Africa have been succumbing to a complex of biotic and abiotic stresses (Otsyula et al, 2004;Ojiem et al, 2006;Kharinda, 2013).…”