An invisible algae known as the "destroyer of plants" is the focus of a meeting that has attracted scientists from around the world to New Zealand.
More than 100 forestry researchers from 14 countries will discuss the threat of Phytophthora, which in one of its forms caused the Dutch Elm epidemic that wiped out a large number of the trees in Europe last century.
Conference convener and forest pathologist from Scion, Margaret Dick, says the meeting will provide a chance for scientists to share the results of their research on a disease often difficult to detect and not well understood.
She says there are species of the organism which have not yet been identified, but when they come into a new environment the problems can begin.
Margaret Dick says Phytophthora is a threat to New Zealand forests because it can survive in plant material as well as soil.
The working party meeting travels on Monday from Auckland to Rotorua, where delegates will be hosted until Friday.