fill foam for trees

October 30, 2006 11:20 AM

I have noticed in a few public parks lately that there is a white foam that has been sprayed into the base of oak trees where the roots join the trunk where there is a gap occasionally. I assume that this is like foam insulation for the home. Is it something that I should think about for my oak trees? I have read conflicting answers about doing this for holes in the trunk but I am not sure if this might be something different since it is at the base of the tree.

To explain further, what I am talking about looks like shaving cream and it is sprayed into the areas around the base of the trees where roots come together form an arch. It is something that I do worry about because it does look like a great place for bugs or whatnot to live and it stays damp. All of our oak trees have these around the base.

It is not sprayed all around the tree though, it is just filling in the arches between roots.

posted by GrumpyMonkey to home & garden (5 comments total)

Arborists are generally no longer sealing gaps, holes and cut surfaces of branches with cement, tar, sealants etc. except in certain situations where it could improve the appearance of said tree(1).

What you are describing is something I have never seen on an Oak tree at all. Bugs are mostly beneficial save certain situations where an already weakened tree will be more subject to infestation. If you are concerned about them, the first thing you must do is identify the insect and level of population. Next is to get reliable advice from someone in your area about whether the tree is at risk. Find a qualified arborist as there is a lot of old/erroneous/damaging information in the realm of trees.

I can't say about the area at the roots staying damp as you haven't said what kind of Oak it is. If you live in Georgia, this might be normal and acceptable. Either way, sealants never truly seal an area and will usually just prevent it from drying out when it would ordinarily be able to. This is because moisture will get in and not be able to evaporate when the weather is dry.

Try looking up your local Ag extension (here?) and inquire further. You might also call the city that cares for the park as it could be pranksters or an incompetent groundskeeper(or, I admit, a special technique(that I've never heard) of being applied properly).

Glad you are wanting to care for your Oaks, they are a pleasure to have on one's property :)

(1) Pirone's Tree Maintenance, Seventh Edition. Oxford Press. p.160-161
posted by a_green_man at 12:26 PM on October 30, 2006

I know that in damp weather some of our trees have foamy-looking secretions around the base or occasionally in the crotch of a branch, and I can guarantee it's not being sprayed in there by anybody. I always assumed it was just sap or something bubbling out and getting washed to the base of the tree by light rain.

This may or may not be what you're seeing, but I thought I'd point it out as a possibility.
posted by ook at 12:54 PM on October 30, 2006

Out in California, the tree trunks are painted white at the base to prevent them from exploding. Really.

In the winter, especially in the desert areas, such as Palm Springs, the temp can vary greatly during the early morning and the afternoon.

On especially cool nights, such as winter, the tree trunks condense, and, when they heat up again during the day, the trunks can expand enough to burst.
posted by Monkey0nCrack at 2:43 PM on October 30, 2006

So the city paints bases of the tree trunks white to reflect the sun more effectively, preventing them from exploding.
posted by Monkey0nCrack at 2:44 PM on October 30, 2006

I'm late to this question, but I'll second ook's response. It's possible what you're seeing is some type of slime mold taking advantage of the damp root areas of the trees.. it's pretty bizarre stuff!
posted by everybody polka at 7:57 PM on November 2, 2006