Putting red needle cast (RNC) management tools into the hands of foresters

Red needle cast (RNC) is shifting from an unknown threat to a disease New Zealand foresters can actively manage. The release of the RNC Manual and Regional Risk Forecasting Tool this month marks an important step in that transition. The RNC Manual summarises current RNC knowledge, guiding foresters on how to integrate this information into disease management programmes.

The RNC Regional Risk Forecasting Tool uses recent weather conditions to indicate the likelihood of an outbreak, helping to anticipate risk periods and when management actions may be required.

First seen in New Zealand in the early 2000s, RNC is caused by the aerial pathogen Phytophthora pluvialis. Although likely native to the United States and now reported in Europe, it is only in New Zealand that the pathogen has had significant impact on radiata pine, limiting the availability of relevant international experience.

Since 2019, the Resilient Forests Programme – co-funded by the FGLT and the Bioeconomy Science Institute – Scion Group – has combined long-term field monitoring, operational-scale field trials, controlled laboratory experiments and modelling to quantify disease impacts, identify environmental drivers and evaluate practical controls.

In worst cases, each severe outbreak can reduce radial growth by up to 31 percent over three to four years. Repeated outbreaks every three to four years could reduce radial area growth by ~20 percent over a rotation.

The programme has developed numerous tools and resources in addition to the risk forecasting tool, including remote sensing and diagnostic tests for disease detection and monitoring.

The team is now focused on operationalising and improving these tools with industry partners through the development of company-specific management case studies and wider industry workshops.

Contact Stuart Fraser or Emily McLay if you would like to know more.