Dutch elm disease spells doom for more than 1,000 trees in Kadriorg Park

Over the next five years, more than 1,000 Scots elm as well as a few European white elm trees will have to be taken down at Kadriorg Park after being stricken with Dutch elm disease, said Ain Järve, director of the popular Tallinn park.

Speaking to ERR, Järve said that nearly 90 percent of the three-century-old park's Scots elms (Ulmus glabra, or harilik jakalas in Estonian) have been infected with Dutch elm disease (DED), which, as the Estonian word for the disease suggests (jalakasurm, or literally "elm death"), kills off elms.

"This deplorable pathogen has now reached Tallinn and Kadriorg Park as well," he continued, adding that what they're currently looking at is an especially virulent strain of the disease from the U.S.

"While our previous understanding was that the incubation period [for fungal disease] is five to seven years, and the trees use their resources to fight it off, the trend over the last three years of our summers getting very warm for very long periods of time has exacerbated this [disease's] aggressiveness," the park director explained. "The most ideal temperature for this disease is over 25 degrees [Celsius], which means that the incubation period has gotten very short."

In a five-year perspective, Järve said, the majority of the Estonian capital's Scots elms and European white elms (Ulmus laevis, or künnapuu in Estonian) will have disappeared from the cityscape.

"The urban space likewise aptly demonstrates how trees will totally unexpectedly drop their leaves after Midsummer, and then it's yet another case of one tree or another that won't be seeing another season," he added.

"So what's the alternative?" he continued. "Our good Finnish colleagues are currently offering the alternative that as Scots elms have an incredibly good reproductive capacity and a very rapid primary growth phase, then within that timeframe new generations of Scots elms and European white elms will be born, which gives us high hopes that it will be possible to find resistant ones among them. Then we can start breeding the resistant ones, and then some 20 or 25 years from now we'll have considerable volumes [of them] again."

Of course, disease resistance brings with it the risk that these trees would be even more susceptible to infection by some new disease.

The park director acknowledged that he doesn't yet know what species of trees will be planted to replace the stricken elms, but added that not a single elm is slated to be cut down before winter.

Kadriorg Park is celebrating its 305th birthday on Saturday.


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Editor: Aili Vahtla

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