Research to understand the fundamentals of the red needle cast (RNC) life cycle has quantified the climatic drivers of the disease. A Scion team, led by Dr Emily McLay, is now developing a process-based infection-risk model to predict how the disease will behave under different climatic conditions.

“RNC incidence is very variable both within and between seasons, and it can progress very quickly,”says Emily.“By the time symptoms are visible, it’s often too late to spray. Thanks to several years’ field data collection, backed by lab experiments, we have a good understanding of how each phase of the disease’s life cycle is influenced by climate, especially temperature and moisture. For example, we know that needle wetness is needed for the disease to spread, and what the temperature thresholds are for each life-cycle stage. We still have questions around how the disease survives when it is latent, and exactly how it spreads.“

A prototype of the model, which is being designed to become a decision-making tool for forest managers, will soon be ready for testing. The team now needs to understand exactly what readily available climate data forest managers have, and how site-specific the data need to be to predict disease behaviour.