Invasive Plant Parasite in Europe Revealed to be Widespread

Elm trees in Europe face a host of issues, and one of them is a parasite known as Meloidoggyne ulmi. Now, scientists have found that a synonymous parasite, known as Meloidoggyne mali has been in the Netherlands for more than fifty years and have discovered exactly how it was introduced.

M. ulmi was first described in Italy on the elm tree species, Ulmus Chenmoui. This parasite has also been associated with other plant species. It can cause severe galling symptoms in the host plant, which can interfere with water and nutrient uptake from the soil. Over time, this can kill the host.

Yet M. mali was first described in Japan in 1969. It's only recently been deemed to be synonymous with M. ulmi. It can impact a variety of species, including apple and elm. Like its counterpart, it also can cause severe galling symptoms.

Currently, the parasite can be found in about ten European countries. These include Belgium, England, France, Ireland, Italy, Spain, Denmark, Germany, Slovakia and Romania. In this latest study, the scientists tested M. mali on more plant species that were found to be hosts for this nematode species. In all, the scientists made a list of about 44 different plant species that are currently recognized as hosts to M. mali. That said, it's very possible that there are even more species that could play host to this nematode and that it could have a much wider distribution in Europe than currently thought.

That's not all the scientists found, though. They also discovered that M. mali was probably introduced during a breeding program on elms during the Dutch Elms Disease (DED) outbreak. During that time, large numbers of elm rootstocks and seeds were imported from several different countries. Because of this, the nematode has managed to gain a wider hold.

The findings reveal a little bit more about the spread of this species. This, in turn, could help scientists better understand how to protect elms and other plant species in the future.

The findings are published in the journal ZooKeys.