Oak processionary moth (OPM) is a continuing issue at Kew, while Phythopthora ramorum is a potential problem. "Climate change is driving this but we think the increase in the movement of material within countries and across borders is driving this more than anything," said Taylor.
He added that OPM is prevalent in the cold climes of Berlin and that even this cold winter will not kill off eggs. Taylor said Kew hopes to reduce OPM numbers by spraying known affected trees in 2010 but knows that surrounding parks and gardens are not as well equipped.
Professional gardeners at historic gardens are dealing with issues closer to home before looking at the global picture. Cambridge University Emmanuel College head gardener Christoph Keate said: "I don't see new challenges. We are always striving to keep a step ahead in environmental terms, reducing chemical use and using best practice.
"A big concern is how mature trees are affected by climate change. Our horse chestnuts make it look like autumn when it is summer. We're slightly removed from the commercial side of horticulture and the financial pressures wholesalers and producers face. The challenges we're facing are to maintain the beautiful gardens for students and staff without our day-to-day operations impacting on them."
London-based Middle Temple head gardener Miranda Kimberley said the hard winter could mean some plants need replacing. But she is also seeing early flowering, which leaves plants vulnerable to the current cold snap.
"We might see an increase of diseases to trees too," she added. "We've had a plane tree die through a fungus and we've had pests on Paulownia that are similar to plane dieback, we think because of the warm climate."
But Kimberley said many public and botanic gardens are immune to the economy: "People are more worried about feeding themselves and their jobs than they are about filling their gardens with stolen plants."
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