The CISP blog has had a pause while I travelled in Italy, Slovenia, and Croatia. My purpose was tourism … but I could not forget my interest in invasive species! Most prominent was that global traveller, Ailanthus altissima. I saw lots of the trees in both urban and rural settings. I am unclear about whether some other plant taxa are native v. non-native, e.g., ivy and several species of pines widespread along the Dinaric mountains. Scotch broom Cytisus scoparius was widespread along the Dalmatian coast – but it is native there so not a concern. (Should have been a warning that it would invade other areas with Mediterranean climates!) We were told that the city of Split is even named for the shrub – a shortened/corrupted version of the Greek name for the plant.
Regarding tree-killing pests, I was pleased to see lots of young olive trees along the Dalmatian coast – apparently the Xylella fastidiosa bacterial pathogen that is killing trees in Italy, France, Spain and Portugal is not yet a problem there.
I also saw many of the columnar cedars that I understand are under attack by fungi in the genus Seiridium in Italy. I also saw apparently healthy boxwoods at our hotel near Dubrovnik.
Some of the boxwoods growing in monastery cloisters in Dubrovnik looked as if they have been hit by box tree moth (Cydalima perspectalis) — which is no surprising since the pest was detected in northern Croatia a decade ago.
Finally, I saw apparently healthy plane trees growing in parks in Bologna; apparently this region has not yet been invaded by the canker stain disease caused by North American fungus Ceratocystis platani. – reported to have caused high levels of mortality in Italy, France, and especially in Greece. (See photo at top of blog) [See Tsopelas, Santini, Wingfield and de Beer. 2017. Canker stain: a Lethal Disease Destroying Iconic Plane Trees. Plant Disease. 2017. 101:645-658. American Phytopathological Society]
I am concerned that the forests at Plitvice National Park are composed of European beech, which is vulnerable to beech leaf disease if it arrives there.
Posted by Faith Campbell
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For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
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