2013 September: Wannamai to Geraldton Sick Trees (Western Australia). Pesticide: Metribuzin

Railway bush reserves are highly important both as ecological corridors and as community assets. With the recent extensive tree decline noticed along the railway between Wannamal to Geraldton involving York Gums, Salmon Gums and Wandoo, investigations led by MCC have followed. Rachel Walmsley, MCC’s NRM Officer said “MCC has organised two stakeholder meetings in the past few months. The initial meeting with Brookfield Rail in January discussed the issue and the community’s concerns on why thousands of trees along the railway suddenly becoming sick in Spring 2013. Outcomes included leaf/soil sampling of affected areas and further investigation by Brookfield Rail.”
A follow up meeting was held in March in Moora between Brookfield Rail and even more concerned stakeholders than the first meeting. Rachel said “Leaf/soil samples results concluded that the residual herbicide chemical Metribuzin is to blame for the tree decline. This has been used by Brookfield Rail with Glyphosate to control weeds including resistant rye grass, and had been used for the previous two years prior to 2013 without ill effects. It is thought the rain events/wet spring may have unfortunately allowed the chemical to infiltrate the soil and reach the tree roots.
The long dry summer has also not helped with tree recovery. “Lengthy discussions were held on Brookfield Rail’s weed spraying protocol including chemicals used, technique and timing. Brookfield Rail said they are reviewing their procedures and that Metribuzin would not be used again on the line. Chemical selection is made in conjunction with the Australian Glyphosate
Sustainability Working Group to avoid weed species developing glyphosate resistance.
Rachel said “Actions to be taken by Brookfield Rail include using a proven nutrient injection technique to bring back a number of prominent sick trees including those through Moora and Coomberdale.” This happened in April with 180 trees being injected. Monitoring by Brookfield Rail will be long term to gauge success. Recovery of a large number of trees is expected
over the autumn/winter but this will be reviewed in the spring. Brookfield Rail will also commit to a wide scale planting program if necessary. This will be discussed at the next meeting in the spring.