Fighting live oak soft tissue rot in northern California

Over night the foam exploded in new art structures.

It started when a branch from my oak tree broke and landed on the neighbor’s power lines. I knew one of my live oaks was dying; I just didn’t want to deal with it. In retrospect, I was pretty lucky. The heart or soft tissue rot that had caused the branch to break could have done far more damage. I have 6 live oaks in my northern California backyard and I really want to keep them healthy.

Stop! Have professional trim your trees.

I have taken off limbs of other oaks trees that exhibited the same bark peeling symptoms. Once the bark starts to peel off, we know the cambium layer is dead. As I have learned, there are a couple different fungi that can infect and kill the heart or soft tissue of the oak tree. While not always, most of my heart rot problems have come from inappropriate branch cuts years earlier by the previous owner.

Help! I’m in over my head

My son and took care of the single broken branch, but I knew I needed real help to take out the whole tree that was dying. Chris Flood of Bailey Tree Care came out and prioritized taking out the dying oak along with maintenance on some of the others. One item he spotted was a deep well of rot at the base of a different tree. He suggested I fill the cavity with the expanding foam to keep out standing water and hopefully retard the overall rot.

Having fun with exploding foam

After the rains stopped and the base dried out, I cleared all the dirt and leaves that had built up in the rotten well. The way live oaks branch early into multiple trunks seems to make them more susceptible to rot. I have noticed this around Folsom Lake as well on my bike rides. I bought a can of the expanding foam used for insulating around doors, windows and attics. I filled the whole 10″ x 12″ cone-shaped hole with what seemed insufficient foam. I thought about getting another can but figured it was good enough.

Foam, a new art expression

I came back a couple of hours later to see the foam had really expanded at least doubling in size. Had I known the expansion, I would have put some plastic and wood on top of the foam to force it to fill the entire cavity in the rotted well. By the next morning the foam seemed to explode out one side. Even though they say you can cut and sand the foam when it dries, it looked so funky and art-like, that I decided to leave it.

Spray on bark

The ultra violet rays of the sun quickly decompose exposed foam. Not wanting a shiny paint job, I picked up a can of textured spray paint. I went with gray to hopefully blend in with grayish color of the live oak bark. While it is not perfect, the whole can of spray paint should protect the foam. Eventually leaves will fall and dirt will get on the paint to soften its appearance. I know it is not a perfect solution, but I am hoping that the foam fill will allow my back yard resident to stay healthy for several more years.

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