Root-knot nematodes, Meloidogyne spp., on potato in Portugal

Abstract

Root-knot nematodes (RKN), Meloidogyne spp., are among the most economically important nematodes in agriculture and can cause significant losses in potato (Solanum tuberosum L.), in both warm and cool climates, depending upon the nematode species (Brodie et al., 1993; Greco, 1993). RKN have not yet been recognised as serious nematode pests in the potato-growing areas of Portugal. However, during the past 10 years, nematode damage has been found in some areas and it is clear that infestation of potato fields by RKN is becoming more widespread. Some of the RKN species attacking potato, e.g., M. chitwoodi, also have quarantine status and one isolate originating from Portugal has already been included in a molecular study (Powers et al., 2005). The aim of this work was to provide data on the identification of Meloidogyne spp. on potato in Portugal. During a survey for potato cyst nematodes (PCN), Globodera spp., RKN isolates were detected in tubers and in soil collected in 210 potato fields in various districts of Portugal (Table 1). When tubers infected with RKN were detected, egg masses were collected and susceptible tomato plants (Solanum lycopersicum L.) cv. Easypeel were inoculated with ten egg masses/pot. When only soil samples were taken, tomato plants with four true leaves were transplanted into the original soil. All plants were maintained in a glasshouse at 25-30◦C. After 45 days, plants were uprooted, their roots gently washed free of soil and females, when present, collected with forceps under a stereomicroscope. Morphological characterisation was based on a minimum of 20 perineal patterns (Taylor & Netscher, 1974; Hartmann & Sasser, 1985). Their char-