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Joco from Camden, Ohio writes

Can Monterey Garden Phos be applied with Pentra-Bark to the trunk of a mature red oak to manage root rot?

I'm aware it's used to treat sudden oak death (Phytophthora ramorum), but could it be effective against Phytophthora species that cause root rot? The tree is declining slowly and there's a few bleeding cankers on the trunk.


The Monterey Garden Phos Systemic Fungicide is safe to be mixed with a surfactant such as Pentra-Bark and applied to red oaks and other trees. We unfortunately couldn't say how effective it would be on other species of Phytophthora since its not been labeled or tested for them. The application wouldn't harm the tree and usually some form of disease treatment would help. We would recommend potentially partnering with a company local to you to see if there are any other steps they suggest based on the current look and condition of your trees. 

Answer last updated on: 03/02/2021

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