31 July 2023

New Zealand’s ‘biosecurity team of 5.2 million’ are being encouraged to look out for pests and diseases which threaten our planted and indigenous forests.

Scion scientists specialising in forest health say there are a myriad of insects and plant pathogens that could wreak havoc in our forests should they ever breach our borders.

To support biosecurity efforts, they are calling on New Zealanders to do their bit by reporting anything they see as suspicious or out of the ordinary.

Scion entomologist Stephanie Sopow says New Zealand is a world leader in biosecurity, with excellent systems to prevent the arrival of forest pests and diseases. But she warns it is still possible an insect or pathogen will slip through the border and trigger an incursion.

“Should this occur, early detection in our forests is the best protection to increase our chances of slowing or halting the march of invasive pests and diseases, which could decimate our forest ecosystems and disrupt the productivity of an industry that is our country’s fourth largest export earner.”

The forestry and wood processing sector contributes $6.6 billion in export earnings to the economy each year.

Forest owners, managers and people working around forests are already highly motivated to keep an eye out for pests and disease. However, Sopow points out it is in the interests of all New Zealanders to be vigilant about reporting symptoms of disease or pest damage on trees.

“Production and native forests deliver enormous benefits to New Zealand. These include the ability of our forests to store carbon, reduce erosion, improve water quality, reduce the effects of floods and enhance biodiversity.

“Our forests and the outdoors are also an integral part of our national identity, adding value to New Zealand as a tourism destination and by providing environments for a range of recreational users.”

“We urge everyone who interacts with trees and forests to be aware of these biosecurity threats so they can quickly identify and report symptoms to authorities.”

While some threats are specific to certain production species, others are ‘generalists’ that could impact a broad range of trees, including natives, ornamental, or amenity trees that are planted for landscaping or shelter.

Tell-tale signs revealed

With support from the Forest Growers Levy Trust, Scion has prepared biosecurity factsheets to help raise awareness of the tell-tale signs of an incursion and profile some of the most unwanted pests and diseases.

One of these is the eastern five-spined bark beetle that attacks pine trees and is a major risk to New Zealand’s planted forests should it ever cross the Tasman. Native to North and Central America, the bark beetle was introduced to China and Australia where it is now widespread. Economic losses attributed to this species in North America and Australia are in the tens of millions every year.

Giant pine scale is another concern to foresters, as its main hosts are pine species. Infested trees may suffer dehydration, defoliation and branch dieback, with heavy infestations known to kill trees. The industry is also on alert for symptoms of the common pine shoot beetle. Adult beetles damage the growing tips of healthy pine trees by boring into the tree to live over winter. This results in distinctive dead tips.

The hairy brown patterned caterpillar that feeds on conifer species before turning into the adult nun moth is another threat. Severe infestations can strip trees of their foliage, making them more vulnerable to other pests and disease.

Some biosecurity threats have made their presence felt in New Zealand. Tōtara blight, a disease caused by a fungus-like organism Phytophthora podocarpi that causes tōtara needles to turn brown, was first reported in Gisborne in 2011. It has been found in old bush remnants around the North Island but scientists say it’s still unclear where the disease originated. To date, it has not been recorded in the South Island and it’s hoped public awareness about the disease will help authorities learn more about its actual distribution and prevent it from spreading further.

Sopow says being able to find and identify the threats as early as possible offers government and industry the best chance of dealing with any harmful new or recent arrivals.

“Ideally, if you find a threat early enough and it has a limited distribution, New Zealand will have a greater likelihood of a successful eradication. If eradication fails or is not possible, we’d need to quickly move into attempting to contain it in an area.”

As required by the Biosecurity Act (1993), anyone who encounters tree damage caused by what they suspect is a new or unusual organism (i.e. not normally seen) they should report these to the Biosecurity New Zealand Pest and Disease hotline – 0800 80 99 66, or via the online pest or disease reporting form - http://report.mpi.govt.nz/pest. These are 24/7 services that allow individuals to freely report suspected pest or disease sightings. After receiving a call, the Ministry for Primary Industries will coordinate how best to proceed with sampling and identification.

For more information about unwanted forest pests and diseases, visit the Biosecurity factsheets page.