Can I cover a tree stump to prevent mushrooms from growing from it? ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Question

My wife and I recently took down a tree in our backyard in an area that is mostly moist all year round and has no direct sunlight. We have since put lots of gravel over the area. Although the area is covered, we are getting many mushrooms growing in the area of the stump. We have been diligent in removing them and we have sprayed the area multiple times but the mushrooms keep growing back. We are worried as we believe the mushrooms might be poisonous and our kids play in that area at times.‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

We were wondering how to attack this problem. ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Currently we plan to remove the gravel and put down soil and flatten it out, then put down a drain-able tarp and them some flagstones.

Does this sound like a good idea and will it work?‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Answer 1

Your plan will stop the mushrooms from growing through, yes. Especially if you have gravel/dust between the flagstones, above the geotextile fabric.

Sounds like a plan. But one thought. The stump will still decompose, and as it does, shrink in size, and leave a very uneven surface eventually. The bigger the tree, the worse. On large trees, there will also be noticeable sinkage where the larger lateral roots grew right under the surface.

Not much you can do about that, except have the stump ground out, the chips removed, and packing soil in where the stump was. Or waiting until the stump decomposes naturally, but that can take many years.

Alternatively, you can simply proceed as planned, and worry about sinkage issues as they crop up. I don't recommend this, as evening out/filling in soil under the fabric isn't feasible, and you would have to basically redo that whole patch.

Answer 2

Hmm, I think a little explanation about mushrooms and how they function is necessary. When you see mushrooms or toadstools, those are only the fruiting bodies of an extensive underground root system called mycelium. The reason you're getting them in that area is because you have dead wood in the ground (your tree stump and its woody roots) and in fact, the mushrooms are a good thing - it means the mycelium beneath are being extremely busy in breaking down the wood of your dead tree as part of the decomposition process. Because the area is also quite damp and shady, this means fungi can function much better, so the decomposition process is faster - but also produces more fruiting bodies.

If you don't want this process to proliferate over the next few years, then the only answer is to have the stump and roots ground out, as already suggested. Unfortunately, it's likely some mycelium will remain (not all the tree roots get extracted, just the main ones), but there shouldn't be so many, and they will probably decrease over time because their main food source has been removed (the dead tree). After this work has been done, rake the area level and let it settle, then go ahead with paving - but I'm not sure what you mean by 'tarp' - that usually means tarpaulin, but if you want something under your paving, you need a reasonably heavy duty permeable geo textile fabric, something a bit thicker and stronger than the stuff usually sold as 'weed fabric'. This usually goes beneath the sub-base for your paving (sand or aggregate, depending what type of paving) and not directly under the paving. It's not essential to use the fabric, although it's advisable if you use paviours (sometimes called pavers, similar to housebricks in shape and size) which are not grouted after laying, rather than actual paving slabs with grout.