Prevalence, Severity, and Distribution of Potato Cyst Nematode in Nyandarua and Nyeri Counties, Kenya

Purpose: Potato cyst nematode (PCN) Globodera rostochiensis W. is a major soil borne pest of potato globally. In Kenya, it was reported for the first time in Nyandarua County in 2015. There exists a knowledge gap in understanding the population dynamics of PCN under different farming systems and environmental conditions, which shows that it is essential for developing sustainable management strategies.
Research Method: A base line survey was conducted to identify and map out PCN incidence and infestation in Nyeri and Nyandarua Counties. Soil samples were collected from 75 farms from a population of 500 farmers registered in farmers’ groups and community-based organizations following purposive, stratified and simple random sampling methods. PCN incidence, infestation, infectivity, yield loss estimation and soil chemical characteristics were determined. Analysis of variance (ANOVA), Chi-Squared test and correlation tests were applied in analysis using R version 4.4.0.
Findings and Values: There was a significant difference in mean number of PCN cysts between the two counties; (Wilcoxon rank sum test, P<.001). There was significant difference in PCN infestation across the Sub-counties, (Kruskal-wallis test, p<.001). North Kinangop and Olkalou Sub- County recorded extremely high PCN Infestation, high soil infectivity and high estimated yield loss. Soil chemical properties had, little or no influence on PCN infestation with a weak negative correlation between number of cysts and pH (r=-0.20). The findings provide a comprehensive assessment of PCN prevalence and severity in key potato-growing regions of Kenya. The high infestation levels and associated potential yield losses pose a serious threat to food security and farmer livelihoods. Controlling PCN will help improve potato productivity, secure household incomes, reduce economic losses, and enhance national food security in Kenya’s most important potato-producing zones.