Estonia monitors four quarantine pests as climate warms

Estonian plant protection officials are closely monitoring four quarantine pests whose arrival could cause irreversible damage to forests and home gardens, ERR reports.

International trade and a warming climate are bringing new natural threats closer to Estonia. Insects and plant diseases can spread through global supply chains, imported timber and increased travel. The authorities’ current list of threats contains nearly 500 different entries.

Ülle Metsmann, a plant health adviser at the Agriculture and Food Board, said on the programme Ökoskoop that prevention was critical. She said one of the most important measures was preventing new pests from entering Estonia through cargo shipments. Border crossings are high-risk monitoring points where traps should be installed and trees and shrubs inspected, she said.

Changing weather conditions are also increasing the workload of customs and surveillance officials. Milder winters and longer warm periods allow more southern species to survive. Pests and bacteria that previously died because of the cold can now overwinter successfully in Estonian soil or beneath tree bark.

One of the biggest concerns is the emerald ash borer, a small beetle from northeastern China that is rapidly destroying ash trees. After becoming established in Ukraine several years ago, it unexpectedly began moving towards Central Europe. It has now also been detected in Hungary and Slovakia.

Another front lies just beyond Estonia’s eastern border. Four years ago, a viable population of the pest was discovered near St Petersburg, putting local specialists on alert. Metsmann said the insect was a strong flyer, making its arrival from the St Petersburg region highly likely.

The pest is only 1.4 centimetres long and extremely difficult to spot with the naked eye. Estonia therefore maintains 90 special sticky traps along the eastern border and beside major roads, replacing them every few weeks. The insect targets trees already seriously weakened by ash dieback. Its larvae burrow beneath the bark and tunnel directly into the layer through which sap moves.