Phosphite trials for control of Phytophthora agathidicida in kauri – re-evaluation after 10 years

I. Horner, M. Arnet, E. Carroll, D. Hedderley, M. Horner

Plant & Food Research

Completed

2024

Following success with phosphite in in vitro and glasshouse trials with infected Kauri, a series of trials in PA-infested forests was conducted, to test the efficacy of phosphite for controlling kauri dieback disease. Trials aimed to determine if there was any reduction in the rate of symptom development in infected trees and/or improved health of trees in various stages of infection, or potential protection of Kauri trees from infection in the forest environment. Trials also aimed to determine what concentrations and doses of phosphite would be effective against the pathogen, yet safe for Kauri.

This series of trials has provided overwhelming evidence for the efficacy of phosphite injection for the treatment and control of PA infection in Kauri. Lesion healing, cessation of tree decline, and eventual canopy recovery give confidence that phosphite injection is a useful tool for the management of PA pathogen infection.

• Controlling the Disease