Sydney NSW, Australia
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Source: FreshPlaza [summ. Mod.DHA, edited]

Tomato growers stress the serious situation that production has fallen, on average, by 60%. This is due to severe drought, but mainly a plague of nematodes. In some areas of southern Spain, nematodes caused producers to lose 100% of their harvest, as this disease is increasingly resistant to treatments.

If the plague persists, growers are not likely to continue to risk as much investment on this crop. The area under tomato has already decreased and yield has also fallen, with large financial losses to producers. Growers are requesting emergency authorisation for the use of a currently banned soil fumigant (1.3-dichloropropene; see comment and links below) against nematodes. Research has been conducted with other treatments, but none of them have been successful.
Communicated by:

[Root knot nematodes (_Meloidogyne_ species) attack a wide range of plants and cause significant economic losses in many vegetable and fruit crops. The genus contains around 70 species and is found worldwide in tropical and subtropical regions in many types of soil. Symptoms may include stunting, wilting, and leaf chlorosis; large galls are formed throughout the root system affecting plant vigour and even killing the host. Affected plants may show increased sensitivity to other bacterial or fungal pathogens.

Tomatoes can be affected by several of the species (such as _M. enterolobii_, _M. incognita_, _M. hapla_). Especially _M. enterolobii_, although originating in subtropical areas, also poses a serious threat to glasshouse crops in cooler regions. It is considered an emerging and particularly aggressive pathogen with increased virulence against crop varieties resistant to other root knot nematodes. For example, it is able to reproduce on capsicum, watermelon, tobacco, and tomato varieties (including rootstocks) resistant to other _Meloidogyne_ species.

Root knot and many other nematodes can persist in the soil for many years and are spread by plant material, soil, and mechanical means (for example contaminated equipment). Once they have been established in an area, it is difficult to control or eradicate them. Disease management is generally aimed at keeping nematode levels below economic thresholds. An integrated approach is required, including phytosanitation (exclusion), cultural measures (such as long crop rotation with non-host species), nematicides, and use of resistant crop varieties, if available.

1.3-dichloropropene has been banned in the EU after environmental risk analysis (see links below).

Spain autonomous communities:

Root knot symptoms on tomato:,,, and
Root knot nematodes: (with gall) and
_Meloidogyne_ photo gallery:

Tomato root knot nematodes:,, and via
Tomato nematodes emerging in Africa:
Information on _M. enterolobii_:,, and
Information on root knot (and other) nematodes: and
Genus _Meloidogyne_ taxonomy and species list:
All other nematode taxonomy via:
Information and risk analysis for 1.3-dichloropropene:,, and via
- Mod.DHA]


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