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durtgrrl

soil fungus? (long)

21 years ago

Hi y'all--this is a cross-post from the soil forum...

This spring I've noticed that one of my flower beds along the house (east facing wall with deep eaves) was growing quite a few mushrooms out of the hardwood mulch. About 2 weeks ago I noticed some very odd amorphous red-brown and white fungus patches at the surface. I'd been watering with a soaker hose, so I removed it and started digging around. I was rather shocked to discover that beneath the upper ~1 inch of mulch, the mulch and soil was riddled with a whiteish grey-blue fungal material. The mulch was somewhat moist, yet the soil beneath--typically a medium brown sandy clay with good structure--was dry, whitish grey and brown, with almost no structure, and no earthworms (fairly common in my gardens) or other microfauna. This soil horizon extended to a depth of ~14 inches below ground surface, when it abruptly reverted to the heavy, dark brown clay that tends to be below the sandy clay surface soil.

I've never seen anything like this!

A little background on the bed if you'll bear with me:

I began planting there after moving to this house in August 2002. The previous owners had covered the soil with bark chips several years before I moved in and ignored it. Bermuda grass was primarily growing there before I began gardening in it. No shrubs or foundation plantings.

2 years ago I put down a layer of wet newspapers in an attempt at lasagna gardening. The compost I used to build the bed was primarily organic matter--not much in the way of inorganic constituents. The bed did recieve a heavy load of mulch last fall kind of by accident (~6 inches). Oh yeah, I don't use commercial fertilizers or pesticides/herbicides. The area does not recieve much in the way of precipitation due to it's protection by the deep eaves, so I water it on a semi-regular basis.

I had put in annuals, penstemon, iris, hydrangea, and columbine. In the 5 ft long section that is the worst in terms of lack of soil structure and degree of fungus growth, the plants were not doing well--at first I thought they were just dry since it's been quite dry this spring--I've moved them since the soil fungus revelation and they've generally recovered.

Upon the discovery of the poor soil health, I excavated as much of the impacted soil as possible from that five foot stretch (5 ft by 2ft by 14 inches = sore back!). I then backfilled with "clean" soil from other areas of the garden and sifted mature compost, and mixed thoroughly with what remained of the impacted soil that I was unable to remove. I put in some "throwaway" annuals to see what would happen.

Since then I've been searching for information and am at a loss. Any help?? The remainder of that bed is impacted, though not to the same degree. I'm unsure if my "remedy" will work, not sure what I'm dealing with, and hoping I don't need to remove the rest of the soil from that bed.

Sorry for the length of the post :) Thanks in advance!

Comments (3)

  • 21 years ago

    Hello,
    You can take a good sample of the bad soil to your local County Extension Office and they can send it to be tested for many things. Including what you need to do to fix the problem. There is usually a small fee for this and if it requires a lot of tests, the fee can be rather large. A phone call to your County Extension Office can usually give you all the info you need on how to gather the soil for a sample. Hope this helps you, Mona

  • 21 years ago

    I've seen fungus like that in hardwood mulch before. I'm no expert on this sort of thing, and my experience is purely anecdotal, but I've seen this with "young" hardwood mulch (material that isn't aged enough) or that's applied too thickly (more than 2" deep). Because of this I've never determined whether the fungus was the actual problem or just a symptom of one of the unpleasant features of hardwood mulch. When left alone, I've observed that the fungus has just disappeared over time. But who wants a flowerbed out of commission for who knows how long?

    The grayish white stuff is the root network of the fungus. In and of itself that's not typically inimical to plants. The thing is that fungus can grow in conditions that plants can't survive, which might mean once again it's a symptom, not the cause of your problem.

    The culprit may be the hardwood mulch itself. It can cause problems besides that fungus -- it raises soil pH over time (not a good idea in parts of middle TN, where the soil runs neutral to alkaline naturally), and, of course, it ties up nitrogen as it decomposes. Pine bark/pinestraw avoids these problems, and I've never seen that fungusy growth in pine bark. And I use a ton of it -- I don't use hardwood on any of my clients' plantings.

    Marty

  • 21 years ago

    Thank you both for your responses. After more reading since I posted, I suspect the mulch as a cause or at least a catalyst for transforming borderline conditions for plant growth into less optimal condition. And I never thought to call the Extension Agency! Thanks for the tips!

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