"Research is going on into a leaf spot fungus that has the capacity to specifically - and this is the key to biological control - attack Japanese knotweed," said Lord Taylor.
Meanwhile, CABI is already attacking the species through the use of psyllids - insects that drink the plant's sap. "We are nearly two years into the controlled release of the highly specialist Aphalara itadori," said Lord Taylor.
"If successful, the psyllid should restrict the growth of Japanese knotweed, slow its capacity to spread and enhance the effectiveness of other management efforts."
A Defra representative said: "Research into natural enemies of Japanese knotweed identified two possibilities that could specifically target the plant. Work on a control agent in the form of a fungus continues. No decision on its use has been taken."