FIRST WORLD REPORT OF THE OCCURRENCE OF ROOT-KNOT NEMATODE, Meloidogyne javanica, ON TRUE MYRTLE, Myrtus communis L.

 
True myrtle, Myrtus communis L belonging to Myrtaceae family is an important medicinal herb in traditional medicine and Pharmaceutical industries in Iran. Moreover because of  being evergreen, having dense foliage and ease of pruning, it is planted at steep slopes, grasslands, boulevards and sidelines of parks as an ornamental shrub or hedge of green. It is distributed in southern Europe, Asia, Iran and particularly Zagros mountains in humid and semihumid regions. In a survey of a two- year old field of true myrtle of approximately two hectares located at Kashkan, Sarab Doureh, 60 km from Khoram Abad, signs of decline , chlorosis and stunting was observed in some plants as irregular patches. Roots showed swellings as small galls singly or in groups. Upon dissection of galls under a stereomicroscope, egg masses and mature female of Meloidogye were found inside the infected tissues indicating the infection of the roots by root knot nematode. Second stage juveniles of Meloidogyne were recovered from soil samples collected from the rhizospher of infected plants. Nearly 1500 second stage juveniles / 250 cm3 were counted. Based on the morphological characters of mature females and juveniles, the species was identified as M. javanica which was further confirmed by PCR using specific primers of Fjav and Rjav designed for this species, generating one single fragment of ca. 670 bp. Occurrence of root knot nematode on true myrtle was also observed in a greenhouse of M. communis close to Khoram Abad. There are several references concerning the nematicidal effects of essential oil, leaf powder and plant extracts of M. communis against root knot nematodes, but there is no known report on true myrtle as a host of root knot nematode species. To our knowledge, this is the first record of the occurrence of M. javanica on M. communis in the world.