Background: Potato is a major food crop in the tropical regions of Africa. However, potato yields continue to remain very low in these regions mainly due to use of poor quality seed. The recent development of rapid seed multiplication technique has helped to shorten the duration of certified seed potato (CSP) production and increase the supply of seed. This study assessed the effect of using CSP on yield, input use, and food security among smallholder farmers. It focused on potato growers in central highlands of Kenya, who were in close proximity to a private seed multiplier that uses these new techniques. The study used the propensity score matching technique and data collected from 408 smallholder farmers through personal interviews. The farmers were stratified by use of CSP. Results: The study found positive effect of using certified seed on both yield and food security. There was also a slight increase in input usage, apparently due to pursuit by farmers to optimize the gains from CSP. Conclusion: The study concludes that using CSP has positive effect on smallholder farm households.

Potato yields in sub-Saharan Africa remain very low compared with those of developed countries. Yet potato is major food staple and source of income to the predominantly smallholder growing households in the tropical highlands of this region. A major cause of the low potato yields is the use of poor quality seed potato. This paper examines the factors determining the decision to use certified seed potato (CSP), as well as the intensity of its use, among potato growers with access to it. We focused on potato growers in the central highlands of Kenya and used regression analysis to test hypotheses relating to potential impediments of CSP use. The study found that the distance to the market (a proxy for transaction costs), household food insecurity, and asset endowment affect the decision to use CSP. However, the effect of the intensity of use of CSP depends on how the intensity variable is defined. Several other control variables also affect the decision and extent of CSP use. The study concludes that transaction costs, asset endowment, and household food insecurity play a major role in the decision by smallholder potato farmers to use CSP and the extent to which they do so. We also discuss the policy implications of the findings.

Potato productivity in Kenya has remained below the potential due to the use of infected seed tubers especially by seed borne viruses. A study was carried out to asses the effectiveness of Positive Selection (PS) in managing seed borne potato viruses. Sprouted seed potato tubers of nine genotypes; three commercial varieties and six advanced International Potato Center (CIP) clones were screened in the field for two seasons, Field Generation Three (FG3) and Field Generation Four (FG4), respectively. In each season, experimental plots were divided into two sub-plots in which one sub-plot was planted with seed tubers sourced through Random Seed Selection (RSS) and the other with seed tuber sourced through Positive Selection (PS). Positive selection plots had low visual virus incidences, high number of tubers per hill and yield (t/ha) in both FG3 and FG4 growing seasons irrespective of the genotypes. ELISA test also revealed that Potato Virus S (PVS) (78%) was the most predominant virus followed by Potato Virus Y (PVY) (20%), Potato Leaf Roll Virus (PLRV) (16%) and Potato Virus M (PVM) (9%) in RSS plots either with single or multiple infections. Positive Selection plots recorded low virus incidences of PVS (47%), and PVY, PLRV and PVM were absent in the tubers tested with ELISA. This study concludes that Positive Selection is a good management strategy to manage the seed borne potato viruses, and if adopted, small holder farmers can reduce the yield losses arising from use of virus infected seed tubers.

Bacterial wilt (BW), caused by the Ralstonia solanacearum species complex (RSSC), is the most destructive potato disease in Kenya. Studies were conducted to (i) determine the molecular diversity of RSSC strains associated with BW of potato in Kenya, (ii) generate an RSSC distribution map for epidemiological inference, and (iii) determine whether phylotype II sequevar 1 strains exhibit epidemic clonality. Surveys were conducted in 2018 and 2019, in which tubers from wilting potato plants and stem samples of potential alternative hosts were collected for pathogen isolation. The pathogen was phylotyped by multiplex PCR and 536 RSSC strains typed at a sequevar level. Two RSSC phylotypes were identified, phylotype II (98.4%, n = 506 (sequevar 1 (n = 505) and sequevar 2 (n = 1))) and phylotype I (1.6%, n = 30 (sequevar 13 (n = 9) and a new sequevar (n = 21))). The phylotype II sequevar 1 strains were haplotyped using multilocus tandem repeat sequence typing (TRST) schemes. The TRST scheme identified 51 TRST profiles within the phylotype II sequevar 1 strains with a modest diversity index (HGDI = 0.87), confirming the epidemic clonality of RSSC phylotype II sequevar 1 strains in Kenya. A minimum spanning tree and mapping of the TRST profiles revealed that TRST27 ‘8-5-12-7-5’ is the primary founder of the clonal complex of RSSC phylotype II sequevar 1 and is widely distributed via latently infected seed tubers.