Document Type : Research Article
Authors
1
Graduate M. S student of Plant Pathology, Faculty of Agriculture, University of Tabriz, Tabriz. Iran
2
Professor, Department of Plant Protection, Faculty of Agriculture, University of Tabriz, Tabriz. Iran
3
Associate Professor, Department of Plant Protection, Faculty of Agriculture, University of Tabriz, Tabriz. Iran
4
Professor, Department of Plant Ecophysiology, Faculty of Agriculture, University of Tabriz, Tabriz. Iran
Abstract
The stem and bulb nematode Ditylenchus dipsaci is one of the most important plant-parasitic nematodes with
a worldwide distribution, causing damage mainly in temperate regions. Onion, garlic and alfalfa are its main
hosts. The use of nematode-free seeds and plant propagation materials, crop rotation, resistant cultivars and
chemical nematicides are common methods of its management. Due to the side effects of nematicides on
human health and the environment, the use of safe, cost-effective alternative methods are necessary. In this
study, the nematicidal effects of the essential oils of mountain thyme, oregano, clove, sage and savory as
well as the metabolites of the fungus Scytalidium sp. were studied in comparison to metam sodium under
laboratory conditions. To prepare the nematode population, nematodes were extracted from naturally
infected garlic from the Gogan region of East Azarbaijan province, reared on carrot discs and incubated at 18
± 1°C for 60 days. The effects of plant essential oils, fungal metabolites and metam sodium were investigated
in bioassays with four replicates, and nematode mortality was recorded after 24 and 48 hours. After a probit
analysis, the LC50 and LC90 values were calculated for each of the compounds tested. After 24 hours, the
LC50 values for the essential oils clove, oregano, marzeh and thyme were 1748, 769.2, 1662 and 4913 ppm,
respectively, and for the fungal metabolite and metam sodium were 207.6 and 6.7 ppm, respectively. Gas
chromatography with a mass spectrometer (GC-MS) and a DB5 column was used to identify the components
of the essential plant oils and the metabolites, the results of which are presented here. Based on the LC50
values, the compounds tested caused mortality and population decline of D. dipsaci at relatively low
concentrations, with the exception of sage-flower.
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