Oral Presentation Science Protecting Plant Health 2017

Dynamics of dieback in a naturally occurring parkinsonia population (4411)

Naomi D Diplock 1 , Victor J Galea 1
  1. University of Queensland, Gatton, QLD, Australia

This paper investigates the results of a seven year study monitoring plant health and movement of dieback moving through a stand of Parkinsonia aculeata.  Two transects were established to monitor the natural progress of parkinsonia dieback through a well-established naturally occurring dieback affected site in north Queensland (Australia).  This would serve to gain an understanding of this disorder in its natural state, and to generate a spatial disease model.  Assessment of this site demonstrated a decline in individual plant health over consecutive years, with 98% of parkinsonia plants dying over the study period.  Minimal recruitment of new plants led to an eventual collapse in the parkinsonia population. 

A Marcov Chain model was generated using plant health data from the first 3 years of the study. This indicated that 99.5% plants would be dead in 15 years.  Comparing the model at a time point of 7 years with actual data gave a close match in plant health ratings.   Isolations taken from plants showing symptoms of dieback at the commencement of the trial indicated that Macrophomina phaseolina (Botryosphaeriaceae) was the only species with known pathogenicity on parkinsonia present in the transect site.

Understanding the ecology of dieback, and the role it plays in the population dynamics of parkinsonia is crucial from a management perspective. This information contributes to understanding both the role that dieback can have in control strategies, and to providing an insight into the timeframe involved in this disease process from infection through to plant death. This is the first research to date to assess the temporal movement of dieback through a naturally occurring parkinsonia population.