A SUSPECTED spray drift incident which is potentially affecting thousands of regenerating trees and other vegetation recovering from bushfire is being investigated by Agriculture Victoria.
A spokesman said the department was investigating a complaint made on June 5 about possible spray drift settling onto native vegetation at Holey Plains State Park, abutting the eastern side of a cleared pine plantation.
The man who reported the incident, Anthony Amis, said he noticed the sickly vegetation in early June while undertaking a koala survey for Friends of the Earth near the intersection of Seldom Seen Track and Chessum Rd, in the middle of the state park.
Mr Amis took video of the area which shows die-off of vegetation, much of it on one side, which goes right into the canopy of trees.
Plants on the ground have also been affected.
The die-off occurs for a couple of kilometres along the road and 100 to 200 metres off the road, then stops.
Mr Amis suspects the die-off is attributable to the aerial spraying of a herbicide.
Regenerating growth is known to be particularly susceptible to some herbicides.
"Whatever was sprayed, the wind got hold of it and took it off site," he said.
"Some significant vegetation could have been impacted.
"Easily, thousands of trees have been impacted.
"The trees that survived the fires might not be able to survive the spraying that followed," he said.
Mr Amis reported the incident to the Environment Protection Authority, which in turn referred him to Agriculture Victoria.
He said the area was an important one for koalas, and his work with Friends of the Earth involves mapping where populations are.
Mr Amis said Gippsland had significant koala populations, as their genes had not been compromised through translocation.
The state park is also home to the threatened Wellington Mint-bush, where work is underway to conserve it.
The mint bush is largely restricted to the Holey Plains State Park.
About two thirds of the species' distribution in the park has been mapped, and it is estimated that more than 1000 individuals exist in just 13 populations.
Holey Plains State Park was severely affected by fire early last year.
A spokesman for Agriculture Victoria said it took chemical use seriously and would continue to investigate all reports of potential misuse.