Fertilizer – Root Knot Nematodes Interactions in High Tunnel Tomato Production

Tomato (Solanum lycopersicum) is one of the important vegetables grown in Kenya. It is the second leading vegetable in terms of production and nutritional value after the potato. Tomatoes are mainly grown by small scale farmers in most arable areas with the main production areas being in Kiambu County. Production of tomatoes in Kenya has been mainly under open field conditions until recently where modified high tunnels (‘greenhouse’) were introduced. Tomato production in greenhouse in Kenya is hampered by pests and diseases mainly Meloidogyne spp., known as root knot nematodes (RKNs).RKNs are the most serious threat to utilization of the greenhouse tomato production in Kenya. The efficacy of current management strategies for RKNs is limited. Mineral nutrients are known to be important in plant-disease interaction, particularly plant-soil pathogen interaction. The challenge is that, there is limited information on how the nutrients affect the pathogens and plant’s response to the pathogen infection, whether positively or negatively. Therefore, this study sought to evaluate fertilizer – RKNs interactions in high tunnel tomato production. Field surveys were conducted among small holder famers growing tomato under high tunnel ‘greenhouses’ in Kiambu County, Central Kenya. The field surveys include a focused group discussions which was followed by soil sampling from the high tunnels. A farmer knowledge survey was done involving focus group discussion with 32 groups of farmers in six sub-counties viz.Thika, Juja, Kiambu, Ruiru, Gatundu North and Gatundu South was conducted during the period July – September 2016 using a checklist with open ended questions. About 78.1% of high tunnels were in use for 1–2 years and 62.5% of farmers taking part in the study could identify symptoms caused by RKNs, which resulted in crop loss of 50%– 100%. Seventy-one percent of respondents had positive attitude about high tunnel tomato production. About 82.6% had the soil in which they produced tomato in the tunnels analyzed for nutrition and presence of pathogens, but the majority (71.7%) never followed recommendations on how to amend their soils nutritionally and against the major soil-borne diseases. These findings indicate that more research and information are required so that farmers can optimize high tunnel production of tomato under tropical conditions. To determine effects of soil chemical properties on abundance of nematodes in high tunnel tomato production. Soil samples were collected from the 32 high tunnels in the six sub-counties of Kiambu County between January and November 2016. Nematodes of various genera and soil chemical properties were evaluated from composite soil samples collected from the high tunnels. Soil pH and N, P, K, Ca, Mg,Na and Cu varied significantly (P =