Chestnut blight, mistletoe keeping city's treekeepers busy
tree population are adamant that Ukraine’s capital doesn’t need any more trees.
“Green plantations constitute 67 percent of Kyiv’s territory,” said Valentyn Didenko of Kyivzelenbud. “We don’t need to turn it into 100 percent, and live in the woods.”
What Kyiv’s trees do need, they say, is maintenance, care, and pruning; in short, to be put in order. That raises the question: what’s so wrong with Kyiv’s trees?
Chestnuts in distress
For the last five years or so, Kyiv has annually been seeing something worrisome. Kyivans’ pride, the chestnut trees that blossom so beautifully in May, have by July started to fade, their leaves turning brittle and curling downwards, like they should be doing when autumn comes. Scientists have been debating whether the cause of this is the deteriorating air-pollution situation, the unusual heat Kyiv has seen in several recent summers, a new chestnut blight – or all of these at once.
In the 1990’s, a relatively little known moth-like insect known as the “horse-chestnut leafminer” was first discovered in the Former Yugoslav Republic of Macedonia, explained Yurij Bihun, a forest resources analyst from Vermont, U.S. Its larvae destroy the chestnut leaves in which they’ve been laid, preventing the tree from accumulating enough reserves for winter and next spring, and eventually the tree dies.
Within just a decade, the moth spread to Austria, Hungary, Germany, Slovakia and the Czech Republic. By 2003, all chestnut trees in Prague were heavily infested. Lately the moth was also discovered in Lviv and smaller Western Ukrainian towns.
Kyiv is just starting to show signs of the infestation, says Bihun, currently a Fulbright Scholar at the Ukrainian State University of Forestry and Wood Technology in Lviv, but given the city’s dense population of chestnuts, the effect could be devastating.
Combating the spread
According to Bihun, burning or composting fallen leaves is the main method used across the world to prevent the blight’s spread.
Insecticides and sex pheromones are also being used, but these measures are too costly for Ukraine, at between $5 and $30 per tree. Besides, they can be ecologically harmful and require properly and carefully applied dosages. Pheromones work by attracting male insects, thus keeping them away from the females and preventing breeding.
Kyiv’s specialists say they have the moth problem under control. “We isolate the infested trees and burn the foliage,” Didenko said. “So far it’s not a mass problem, and only individual trees have been infested.”
Most chestnuts with faded leaves are actually not afflicted by the moth, Didenko said.
“It’s the traffic jams that cause the most damage – the cars’ exhaust plus the scorching sun do it.” Didenko said he has been often observing trees that grow in groups, and finding that those to the south dry out, while those to the north or in the shadows are green and healthy.
“To escape the heat, trees stop evaporating – their leaves dry out,” he explained. “The fact that they recuperate next spring proves that it’s not the leafminer.”
Under the mistletoe
“If I could just ship all that mistletoe to my home country and sell it at a Christmas fair, I’d be a millionaire,” a Swedish tourist recently visiting Kyiv was heard saying.
In the early independence era, when there wasn’t enough money around to worry about the health of trees, parasitic mistletoe spread so much in Kyiv that scientists were able to make an important finding. “We discovered that mistletoe afflicts practically all trees, more than 100 species found in Kyiv parks,” said Yury Klymenko of Kyiv’s Central Botanical Garden, in Pechersk. That includes birches, ashes and Lombardy poplars, he said, which earlier weren’t considered susceptible to mistletoe.
Mistletoe grows by insinuating its roots under the bark of its host tree and sucking all the nutrients from its sap. Eventually the afflicted branch dies, leaving as the only alternative amputation, itself a tricky business given that it’s hard to tell where mistletoe roots end. If they’re not all cut out, the mistletoe will grow back.
Four years ago, the Kyiv City Administration launched a massive campaign to restore Kyiv’s parks. The Central Botanical Garden’s researchers were given the mandate of studying the spread of mistletoe in Kyiv and figuring out why it was so prolific.
Klymenko says most infected trees carry between one and ten mistletoe bunches, but there were some with up to 50 of them. Such trees could only be cut down, as it was impossible to save them.
“We took the right measures at the time and didn’t allow a massive outburst,” said Klymenko. “The city has been cleaned noticeably, but of course there’s still a lot of mistletoe left. The struggle continues.”
The main problem is that mistletoe, whose seeds spread through bird droppings, keeps coming back to the city from territories outside Kyiv, where no one really is in charge of the trees.
Construction boom
Surprisingly, Kyiv’s current construction boom is giving those who work with the city’s trees much more to do, because they have to manage more efficiently a smaller amount of space: now that there’s less green space, there’s less room for things to go wrong.
“Whether we want it or not,” Didenko said, “free space in the city will be reduced. Kyiv will become denser.”
One response to that phenomenon is to increase what experts call the “recreation capacities” of existing parks: building more alleyways, paths and benches. Park authorities have started increasing the capacities of parks in the city center, and are gradually moving outward.
A recently adopted Kyivzelenbud greening plan for 2004-2010 foresees the refurbishment of the huge parks on Syrets – from Babyn Yar to Kyrylivska Church – and on Batyiva Hill. It also provides for cleaning up the chain of parks around Lvivska Ploshcha, in the hills and ravines along the Andriyivsky Uzviz, and from Podil all the way up to Arsenalna metro.
In the Feofania Preserve, restoration of the centennial oak forest and the cleaning of ponds and cascades is being planned.
When all this happens will depend entirely on the funding.
