Estonia tightens border checks and monitoring as climate change boosts invasive pest threat

Estonia has held a rare EU protected zone status for more than 20 years, meaning strict restrictions on plant imports from other member states and the use of 'plant passports'. Alien species rarely reach the country on their own; instead they arrive with human activity such as global supply chains, timber imports and international travel. The authorities' watchlist now includes nearly 500 different threats.

Ülle Metsmann, plant health adviser at the Agriculture and Food Board, told the radio program 'Ökoskoop' that prevention must start at the border. Border areas are high-risk locations where traps and tree inspections make sense. Changing weather conditions have expanded the workload of inspectors, as warmer winters and longer warm periods allow species from the south to survive in Estonian soil or under tree bark. Climate change favours pests that previously could not establish themselves.

One of the greatest concerns is the emerald ash borer, a beetle native to northeastern China that destroys ash trees. It has not yet been found in Estonia, but after becoming established in Ukraine it has moved into Hungary and Slovakia. Four years ago a viable population was discovered near St. Petersburg, just 150 kilometres from the Estonian border. The beetle is an excellent flyer, so its arrival is considered highly likely. To detect it early, Estonia maintains 90 sticky traps along the eastern border and major highways, replacing them every couple of weeks.

The Japanese beetle is another monitored species. It can hitchhike on vehicles and hide in aircraft cargo holds, prompting surveillance around airports. This beetle attacks weakened ash trees, as well as grapevines, apple trees, maples and roses. After feeding in summer it burrows into the soil, where its larvae feed on roots and damage grasslands.

Specialists also watch microscopic threats. The pine wood nematode, invisible to the naked eye, is found mainly in Portugal and parts of Spain and has recently spread into French conifer forests. It travels inside longhorn beetles that move between countries in wooden packaging material. The Asian longhorn beetle spreads in a similar way and has already been found several times in pallets arriving at Estonia's border. Although the quality of pallets has improved, many exporters still do not treat shipments thoroughly enough, allowing pests to spread freely.

A fourth major threat is fire blight, a bacterial disease caused by Erwinia amylovora that affects plants in the rose family. Estonia has held protected zone status since 2005, and only Finland, Latvia and Lithuania share this status for the bacterium. All host plants, including pears, apples and rowan trees, must come from disease-free nurseries, and every plant must carry a plant passport confirming it is safe for a protected zone.

Because official inspections alone are not enough, authorities rely on the public. Gardeners are asked to check fruit trees and report browned branches or shoots bending downward. Forest visitors can use the PlutoF Go app to map living ash trees and inspect larval tunnels beneath the bark.