Farmers awareness and occurrence of Meloidogyne species in tomato production in central Nepal

Abstract

Tomato (Solanum lycopersicum) is one of the most economically important vegetables in the world. Root-knot nematodes (RKN) form a complex of species that can cause severe losses in tomatoes. Since symptoms and damage depend on the particular nematode species, accurate species identification is critical for implementing potential control measures. Detailed surveys of plant parasitic nematodes in Nepal have not been conducted. Therefore, there is no information on which RKN species occur in key tomato-growing areas. We conducted an initial survey to assess the occurrence and importance of RKN. Nine different districts of Nepal were included: Bhaktapur, Chitwan, Dhading, Dolakha, Kaski, Kathmandu, Kavrepalanchok, Lalitpur, and Lamjung. In the first approach, 70 farmers were interviewed about their awareness and knowledge of RKN. More than 60% of the farmers surveyed knew of RKN and the main signs and symptoms. 40% had limited or no knowledge about it. In a second approach, we conducted a survey of RKN occurrence in tomato fields in the same nine districts. Soil sampling and subsequent analysis in the Kathmandu district revealed RKN infestation at very high levels. Except for Kaski and Chitwan, RKN prevalence was found to be 100% in the districts sampled. The overall prevalence of Meloidogyne species was also 100% in most districts. To identify the species, samples with RKN-infected galls were collected and determined morphologically using perineal patterns and molecularly using specific PCR analyses. Both methods showed that Meloidogyne incognita was the most abundant in the tomato fields, followed by M. arenaria and M. javanica. Our results confirm the importance of RKN in Nepal and suggest that it would be highly beneficial economically to increase farmer awareness of nematode problems and possible control measures.