SummaryParatylenchus (Gracilacus) straeleni (De Coninck, 1931) Oostenbrink, 1960 was detected for the fi rst time in Turkey. Our studied population was found in the rhizosphere soil of hazelnut orchards in Ordu. Females and males were studied morphologically and morphometrically by light microscopy and molecularly by sequencing the D2-D3 of the 28S rDNA gene. We present here the morphological and molecular characterisation, phylogenetic analysis of examined population and comparison of variability of worldwide known populations of P. straeleni.

Essential oils of medicinal and aromatic plants are important and promissing to manage the nematological problems in agriculture. In this study, five of the plants including Origanum onites, Salvia officinalis, Lippia citriodora, Mentha spicata and Mentha longifolia for egg hatching inhibition and four of the plants including Mentha piperita, Foeniculum vulgare, Coriandrum sativum and Ocimum basilicum for juvenile mortality were tested on Meloidogyne hapla under laboratory conditions. The oils were achieved by using water distillation method with a Clevenger apparatus. As the results of egg hatching trial, the highest egg hatching inhibition rate was found as 54% for O. onites. In addition, the other inhibition rates varied as 31.4%, 21.6%, 23.8%, 25.7% for the other plants, S. officinalis, M. longifolia, M. spicata and L. citriodora, respectively. Essential oil of each plant components were determined by gas chromatography (GC). Carvacrol was found as the main component (68.8%) of O. onites followed by Thujone 27.7% for S. officinalis, I-Menthone 76.9% for M. longifolia, Carvone 27.1% for M. spicata and Citral 19.3% for L. citriodora. For the juveile mortality, Mentha piperita showed the highest mortality rate as 93.2% and was followed by F. vulgare 72.9%, C. sativum 69.3% and O. basilicum 64.9%. The main component of the used plants were Carvone 39.3%, Anethole 40.2%, Linalool 81.3% and Linalool 54.6%, respectively.

The study was conducted to investigate the status of soil nematode communities in hazelnut orchards in Ordu province, Turkey. Nematodes were identified to genus level and allocated to trophic groups. A total of 50 taxa were found from hazelnut growing areas including 19 plant parasites, 12 bacterivorous, 4 fungivorous, 4 predators and 11 omnivorous. Genera Tylenchus (94.5%), Gracilacus (79.1%) and Helicotylenchus (56.4%) as plant parasites, Acrobeloides (68%) as bacterivores and Aphelenchoides (68.2%) as fungivorous were widespread and found in all districts. The highest abundance of plant parasites was in Kabataş (277 individual/ 100 cm 3 soil) followed by Gölköy (196.6 ind./ 100 cm 3 soil) district. Criconemella, Meloidogyne, Paratylenchus and Pratylenchus were found as important genera by means of the damage potantial on hazelnut as plant parasitic group. The other trophic groups were at desirable level for an healthy soil system.

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This study was conducted to evaluate some effects of hazelnut dried husk extract and husk compost on nematode infection and some plant parameters of tomato inoculated by mixed root-knot nematodes populations of Meloidogyne hapla and M. arenaria in pot experiment. The dried hazelnut husk obtained from after harvest were used. For both husk extract and husk compost treatment, 50 grams of hazelnut husk was used. Approximately 1000 second stage juveniles (J2) was inoculated to susceptible tomato cultivar (Solanum lycopersicum cv. Rio Grande). At the end of 8 weeks, the gall numbers on the root, number of the juveniles in the pot, plant fresh root weight and total plant fresh weight were measured. As result, the husk compost treated plants had lower gall on the root system and juvenile numbers in the pot soil by comparison with husk extract treatment. For plant growth parameters, the total plant fresh weight was significantly different for husk compost treatment. The all results seemed that the husk compost treatment has more effect on Meloidogyne spp. gall numbers than husk extract application on tomato.

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Swiss Chard (Beta vulgaris subsp. cicla) is a vegetable crops growing in different regions of the world for variying purposes. Root-knot nematodes (Meloidogyne spp.) seem the potantial pest group on Swiss Chard according to the reported species from other countries. In this investigation, the root knot nematode (RKN) extracted from the root of Swiss Chard was identified as M. arenaria by using different primer sets (TRNAH-MRH106 and MORF-MTHIS) targeting the large sub-unit ribosomal DNA (lrDNA) and the intergenic spacer (IGS) of rDNA of mitochondrial (mtDNA). Furthermore, the restriction enzymes (HinfI and MnlI) for the fragments given by TRNAH-MRH106 primer set was also used for restriction and digestion. Finally, species-specific SCAR primers (Far/Rar) were performed to validation of the identification results. M. arenaria is considered as an important species among the major root knot nematodes in the world. In this context, the Swiss Chard as an intercroped, small-scale produced or randomly dispersed commodity must be observed as the potantial host for the nematode. This is especially important in case of any change for long term professional production planning in the same area for more valuable agricultural commodity.