Sweet potato is one of the most important staple food crops consumed in Kenya and throughout Africa but yields are greatly reduced by plant parasitic nematodes (PPN). The aim of this study was to determine the prevalence of PPN in Kenyan sweet potato fields and their relationship with soil and climatic variables. Soil samples were collected from sweet potato fields in Busia, Teso, Kisii, Embu and Makueni counties. Thirteen nematode genera were identified across the five counties with Meloidogyne, Pratylenchus and Rotylenchus being the most prevalent. There was a significant (P <0.05) relationship between PPN abundance and sodium, calcium and iron. Canonical correspondence analysis of climatic variables revealed that the relationship between rainfall and nematode genera was significant (P <0.05) while maximum and minimum temperatures were not significant. This description of PPN assemblages associated with sweet potato in Kenya and their relationship with environmental variables provides a starting point from which appropriate nematode management strategies can be implemented.
This chapter describes the nematode parasites of potato (Solanum tuberosum) and sweet potato (Ipomoea batatas). Information is given on their origin and distribution, biology, symptoms of damage, spread, environmental factors affecting parasitism, other hosts, disease complexes, economic importance, and management measures, which include host resistance, cultural, chemical and biological control methods.
Rice is the third most important crop in Kenya after maize and wheat. Plant parasitic nematodes (PPN) are a major rice production constraint. The objective of this study was to determine the distribution and abundance of rice PPN in Kenya and their association with environmental variables. Soil and plant samples were collected from rainfed upland and irrigated lowland rice fields in Kirogo, Thiba, Nyangati, Ombeyi, Kombura, Kakola and Mwambe Sub-locations. Twenty-two PPN genera were identified across all Sublocations with the highest (20) number of nematode genera recorded in rainfed upland rice fields. The nematode genera Scutellonema, Hoplolaimus, Ditylenchus, Hemicycliophora, Heterodera, Paralongidorus and Tylenchus were not recorded in the irrigated lowland rice fields while Criconemella and Tylenchorhynchus were not observed in rainfed upland fields. Canonical correspondence analysis of the relationship between soil properties and nematode abundance revealed a significant (P < 0.05) relationship between PPN abundance and potassium, sodium, sand and clay. The relationship between rainfall, minimum temperature and nematode genera was significant (P < 0.05) while maximum temperature was not significant (P = 0.928). Our results provide critical information for designing nematode management strategies in Kenyan rice fields.
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