Dendro and his assistant Codit travelled to another state for a trade show. While they were there, they did a client visit on his property. There were multiple trees (including Oaks) and shrubs that suddenly browned and died about a month ago, but there had been no major problems previously. The owner George showed the duo a scenery of the coastline past the house, and explained that that was the reason he bought this property.
He then led them to a group of dead trees and on the way, blueberry bushes and ferns were noticed. George shared that about a month ago he left for a short trip and after he return, he observed that the trees had brown leaves. Shrubs were also browned after another few weeks. A bare path was "created" through ferns on a slope, where it used to be full of live ferns.
Codit came up with a reasoning that the causal agent is abiotic, as there are multiple species that were browned at that area. Just to be sure, Codit used his hand lens to examine different parts of the affected plants to spot for possible biotic causal agents. He then used a Dutch auger to dig up several spots, and observed that the soil seemed normal, not compacted, and not mounded up again tree collars.
Codit postulated that there might be weather extremes like a sudden cold snap or abnormally hot weather, but George stated that the weather had been normal. Finally, he asked George whether they were any recent work or activity done on the slope and the answer was negative.
Just when the questioning was done, the neighbour was seen to have returned and entering the house. George said that this neighbour moved in six month ago and he missed his old neighbour. George's expression soured and mentioned that the new neighbour made comments that he was not able to see the water from his house due to trees blocking the view, and had actually asked George to remove some of the trees on the hillside.
Dendro shared his assessment that the damage and plant tissue death caused to multiple plant species was probably the result of herbicide application. He informed his client that testing for herbicides is possible and that there is a cost for sending plant samples to the lab. There will be one or more screening tests for multiple compounds, as they have no idea what product was applied, and the client agreed to have the lab tests done. Codit then collected foliage that are still alive but showing browning from a few plant species. Dendro assured the client that he would be informed when the results are out.
The lab found tebuthiuron in every plant sample that were sent in two weeks later. They shared the results with the client by phone and George asked if there is anything that could be done for the plants that are still alive. Dendro replied that the herbicide have to be broken down in the environment on its own, and there might be more plants killed by the herbicide in the meanwhile.
The client had contacted a lawyer regarding this incident, and may need to pass the info regarding the vandalism to the authorities.
Reference: Arborist News, April 2023, pages 20, 21, 22, 29, 30
