HA Trim owner Hans Alexandersen, who has seen £60,000 worth of trees hit and is leading an investigation into the cause on behalf of the British Christmas Tree Growers Association, said: "We don't know how big the problem is or how it can be solved. We don't want it to escalate but people don't know how to identify it."
Snowbird Christmas Trees owner Adrian Morgan is working on the investigation with Alexandersen, who he said had "spent a lot of his own money trying to get the disease genome sequenced".
Horticultural consultant John Adlam said he had seen symptoms on Norway spruce as well as Nordmann firs but was not sure of the cause. "It's trying to work out what happened earlier in the season.
"We might not see shortages in 2011 but where people bite into 2012's maturing trees to meet their orders it could have a knock-on effect."