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Date: November, 2007
Source: The American Phytopathological Society, Plant Disease 2007; 91(11): 1514 [edited]
<http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-91-11-1514B>

[Reference: I Pajovic, et al. The incidence of root-knot nematodes _Meloidogyne arenaria_, _M. incognita_, and _M. javanica_ on vegetables and weeds in Montenegro. Plant Dis 2007; 91(11): 1514; DOI:
10.1094/PDIS-91-11-1514B]

Root-knot nematodes (_Meloidogyne_ spp.) are common pathogens that parasitize vegetables and other crops and cause significant yield reductions worldwide. In the early spring of 2006, severe plant stunting, chlorosis, and extensive root galling were observed on cucumber plants grown in a greenhouse on Zeta plain, Zetska ravnica, Montenegro. In the summer and autumn of 2006, infected roots of different crops were collected from greenhouses and vegetable production fields of Zeta plain, which represents the largest area of Montenegro's vegetable production. Several vegetable crops were found to be infected with root-knot nematodes, including tomato (_Lycopersicon esculentum_ Mill.), squash (_Cucurbita pepo_ L.), cucumber (_Cucumis sativus_ L.), pepper (_Capsicum annuum_ L.), and lettuce (_Lactuca sativa_ L.). Symptoms on these crops included root-galling, leaf chlorosis, and stunting. Heavily infected tomato plants growing in 2 greenhouses also displayed early flower and fruit drop.

Nematode species were determined based on characterization of (i) female perineal patterns, (ii) male and 2nd-stage juvenile morphology, and (iii) esterase and malate dehydrogenase phenotypes from young egg-laying females.
The most prevalent species was _M. incognita_, which was isolated from the roots of tomatoes, peppers, cucumbers, and lettuce from 9 locations. _M. arenaria_ was detected at 3 locations from the roots of tomatoes grown in a greenhouse and the weeds _Convolvulus arvensis_ L. and _Solanum nigrum_ L., which were growing in open fields in separate locations. _M. javanica_ was found on tomato and squash in the same field where _M. arenaria_ was also found on _S. nigrum_. _M. javanica_ was isolated from tomato and squash.

In this study, we found high incidence of _Meloidogyne_ spp. in intensive vegetable production areas of Montenegro. The implementation of an effective integrated pest management program is essential for future use of infested areas. To our knowledge, this is the 1st report of _M. arenaria_, _M. incognita_, and _M. javanica_ from Montenegro.

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[Root knot nematodes (_Meloidogyne_ spp.) attack a wide range of plants, including many common vegetables, fruit trees, and ornamentals. The genus contains around 70 species and is found worldwide in tropical and sub-tropical regions in many types of soil.

On infected plants, large galls form throughout the root system affecting plant vigour. Above ground, symptoms may include stunting, wilting and leaf chlorosis, which may be confused with nutritional problems. Severe infections may kill the host plants and often result in significant economic losses to growers. Losses are due to yield reduction as well as to lack of consumer acceptance, for example for carrots which have developed severe forking with galls on lateral roots. Damage usually depends on population density, nematode species or race, and host species or cultivar. Many commonly grown cultivars of tomato and the other crops mentioned in this report can be severely affected by root-knot nematodes, and intensive vegetable cultivation under plastic tunnels often increases nematode numbers in the soil.

The pathogens are spread by plant material, in infested soil, and by mechanical means, for example tools or contaminated equipment. Eggs can persist in the soil for years. Disease management of nematodes is difficult
and generally requires an integrated approach of phytosanitary measures and exclusion, including use of clean planting material and soil, nematicides, resistant host varieties, and crop rotation with non-host species. In some
instances, susceptible cultivars can be grown successfully when grafted onto rootstocks resistant to root-knot nematodes, a method used increasingly, for example, for eggplant in Italy.

Maps of Montenegro:
<http://www.visit-montenegro.com/images/montenegro-precise-map.jpg>  and
<http://healthmap.org/promed?v=42.8,19.2,5>
Pictures
Root-knot symptoms on carrot:
<http://plantpathology.tamu.edu/Texlab/Vegetables/Carrot/Images/carrot4.jpeg>
Root-knot on lettuce:
<http://www.apsnet.org/online/Archive/PDCoverImages/2004v88/jan_1.jpg>
Affected cucumber field:
<http://edis.ifas.ufl.edu/images/679081228>
Root-knot nematode and gall:
<http://www.ipm.ucdavis.edu/PMG/M/N-RK-MSPP-AD.001.html>
Links:
Information on root-knot (and other) nematodes:
<http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7489.html#LIFE>,
<http://cals.arizona.edu/pubs/diseases/az1187.pdf>  and
<http://www.apsnet.org/Education/LessonsPlantPath/RootKnotNema/default.htm>
_Meloidogyne_ species on tomato:
<http://www.avrdc.org/LC/tomato/nematode.html>
_Meloidogyne_ species on cucurbit crops:
<http://edis.ifas.ufl.edu/NG025>
_Meloidogyne_ species on lettuce:
<http://www.funpecrp.com.br/gmr/year2002/vol1-1/gmr0008_full_text.htm>
_M. incognita_ information:
<http://ucdnema.ucdavis.edu/imagemap/nemmap/Ent156html/nemas/meloidogyneincognita> 
and
<http://taropest.sci.qut.edu.au/LucidKey/TaroPest/Media/Html/Nematodes/Meloidogyne/Meloidogyne.htm> 

_M. incognita_ taxonomy:
<http://www.nematode.net/Species.Summaries/Meloidogyne.incognita/index.php>
_M. arenaria_ taxonomy:
<http://www.nematode.net/Species.Summaries/Meloidogyne.arenaria/index.php>
_M. javanica_ taxonomy:
<http://www.nematode.net/Species.Summaries/Meloidogyne.javanica/>
Control of nematodes:
<http://www.krishiworld.com/html/nematodes.html>.  - Mod.DHA]