The Government is to spend £7m on research into tree pests and diseases, and has proposed tightening import controls to prevent the introduction of infected plants.
The Tree Health & Plant Biosecurity Action Plan is a joint initiative with the Forestry Commission. The cash is targeted over the next three years at finding ways of dealing with diseases including Phytophthora ramorum, oak processionary moth and red band needle blight.
Defra hopes to improve the coordination of research into plant and tree health to increase efficiency.
The plan involves strengthening import controls to prevent pests and pathogens being brought into the country. Measures include more funding for inspections at Heathrow airport and other major points of entry and reviewing the EU Plant Health Regime, as well as working on greater international collaboration.
Environment secretary Caroline Spelman said: "If we don't act now we could end up in a similar situation to the 1970s, when more than 30 million trees in the UK died due to Dutch elm disease.
"We need to do everything we can to protect our precious plants, trees and habitats. With the expansion of global trade, especially in live plants, the risk that exotic diseases and pests will be introduced here grows all the time.
"Today's action plan dedicates £7m to finding ways of combating exotic diseases and pests as well as introducing stricter controls on plants and cuttings being brought across the UK's borders."
The amount of funding announced for research into combating new or exotic pests and pathogens affecting trees in the UK - £7m.