Phytophthora ramorum disease has wreaked havoc in forests throughout Europe and the United States, hitting both plantation and native trees hard and felling timber industry work in the process.
The word phytophthora is Greek for plant destroyer.
Scion science leader Lindsay Bulman said the plant pathogen was an unusual cross between a fungus and an alga, claiming its own kingdom in the classification context, and one that came out on top of all his biosecurity concerns in the forestry sector.
“We don’t know definitively if it would infect pine trees but it has been seen on Douglas fir and Japanese larch overseas. Previously, plant pathologists thought it would not infect any conifer species,” he said.
A broader Import Health Standard (IHS) was needed for imported plants that might be capable of carrying the disease.
“The standard could include a broader number of plants that may be capable of carrying the disease.
“We estimate that for every known risk disease there are two we do not know about so the more we can do to reduce the risk of those we do know about, the better.”
Other pathways included potting mix but he believed the standards around that product had been tightened up effectively in recent years to reduce that risk path.
The disease had proved to affect a broad range of plants and its impact would not only be limited to NZ’s commercial tree population, Bulman said.
There was also the proven threat the disease posed to NZ’s ornamental and nursery tree trade. That included rhododendron, camellia and viburnum species.
The disease had moved quickly, destroying oak trees in Oregon and California with deadly efficiency in weeks. Foliage die-back and bleeding cankers were typical symptoms of the disease’s presence.
As with the Psa bacteria, infected trees could act as inoculums for new infections, with pathogen-producing spores spread with splashes and rainwater.
But Bulman said the effect of infection would also deliver a “one-two” punch to the forestry sector, also affecting export markets.
“Log exports from the West Coast of the United States to east Asia have had a major hit from importing countries not wanting to introduce the pathogen there.”
The NZ industry had grappled with a related disease about a decade ago that caused defoliation in pine trees but that brought no reaction from trading partners.
Bulman’s concerns were raised during the Biosecurity Week being held at the Port of Tauranga, an initiative to engage the wider community on taking responsibility with government agencies for border security.
The Bay of Plenty community was particularly aware of the impact of biosecurity incursions and a disease hitting the log trade would be a big blow.
“A third of NZ’s $5 billion a year forest product export trade goes through the Port of Tauranga. If those exports were disrupted there would be a lot a people who work and service the sector who would find themselves out of work for a long time.”
Forest Owners Association biosecurity manager Bill Dyck said the forestry industry had to deal with some significant incursions in the past year including two species of beetles feeding on eucalypts.
