Tuesday, August 04, 2009

Oh, What a Tangled Web....

The more I learn about the natural relationships just in our yard, the more awestruck I am at the complexity and balance within nature....




This summer I've been seeing these big, ugly mushrooms in the grass of our back (court)yard area. They range up to about 8" in diameter, are yellowish-brown on top, and their caps become wavy as they mature, sometimes revealing their yellow undersides in a rather flirtatious way. These mushrooms have very short stems that are generally hidden and often off center. Evidently they are extroverts - in that they usually occur in small clusters.


Yesterday while I was clearing out a new area for a bed, I ran into a large group of them hidden in the grass and weeds that had grown up. There was no way to do the weeding I wanted to do without touching the mushrooms quite often and I began to wonder if I needed to be cautious about handling them. That led, rather naturally, to feeling the urge to identify them.


The first book I checked left me feeling inadequate, so I moved on to A Guide to Kansas Mushrooms. Success! What I had were ash tree boletes, aka Boletinellus merulioides. Not only were these mushrooms not poisonous, they are actually supposed to be edible (with the small caveat that they taste rather like dirt). They are found under ash trees, as their name suggests. Coincidentally, the two trees shading our courtyard are green ash. It all seemed very straightforward.


Being somewhat compulsive about these things, though, I wanted to find out a little bit more about their biology, so I continued my search on the web. That's when I got a few hints that things might be a touch more complicated than they had looked initially.


The first site I visited, Mushroomexpert.com, talked about ash tree boletes not actually being mycorrhizal with ash trees, as I had assumed, but symbiotic with ash tree aphids. Hunh?


Another site said they were "associated with the aphid farming of ants around ash trees."


Finally I found a site by Oregon State University that named the aphid in question, Prociphilus fraxinifolii. Other sites gave me common names for the aphids involved, woolly ash aphid or ash leafcurl aphid. (Multiple common names for the same species of plant or animal is why scientific names are so wonderful.)


While I am not sure that I have the entire life cycle and interrelationship completely figured out, here is what I can piece together so far.... The woolly ash aphid (aka ash leafcurl aphid) seems to feed on the ash tree in two places: in the spring it feeds on newly emerging leaves, creating a deformed, curled effect in them that is especially problematic in young nursery plants; the rest of the year it seems to feed on the roots. The aphids can overwinter either as eggs in the tree bark, or as immatures below ground on the roots. When feeding on the roots, the aphids are surrounded by sclerotial tissue from the ash tree bolete, providing the mushroom with "honeydew" sugars as food in return for shelter and probably protection from predators from the mushroom. Again and again I read that ash tree boletes do not have a mycorrhizal relationship with the ash trees themselves.


So I am left with questions: Have I missed a major wrinkle in this complex relationship? Can the ash tree bolete survive without the aphids? Does the fact that I have numerous ash tree bolete mushrooms this year mean that we will have a bad outbreak of woolly ash aphids next year? (I see no signs of curly leaves on my trees this year, although there could be a few curly leaves hidden within the canopy.) Should I remove and destroy the ash tree boletes to interrupt the life cycle of the aphids? Do I trust my identification skills enough that I'm willing to cook up some ash tree boletes and taste test them?


Time will answer some of these questions. If anyone else has an answer or two for me, I'd be happy to hear them. Meanwhile, I'll just wait and watch...and probably NOT try taste testing. Somehow, the idea of a dirt-flavored mushroom isn't quite appetizing enough to risk much for!

15 comments:

Jeff said...

I enjoyed your post. However my relationship with these pesky shrooms can't be put as eloquently as you have described yours. I too, have found their existance to be confusing. Do they thrive on the ash root? Or do they thrive on the aphid juice? Can I broadcast a pesticide and rid myself of these unsightly stains on my front yard? Or do I need to call in a back hoe and remove a foot of earth and have it replaced with fresh? It's all so confusing. I just wish them gone!

Sean said...

I agree with Jeff. Great post and it is an issue I am very intimate with. These mushrooms if accidently stepped on or die dissolve into a black goo, attracting bugs and smelling terrible. Therefore, they must be picked before they die. But I only wish to see them gone from my back yard permenantly!! How do I eliminate them without replacing the turf?

Gaia gardener said...

I have no idea how to get rid of these mushrooms if picking doesn't work, other than cutting down the tree and replacing it with a different (non-ash) species. That seems awfully drastic.

This is my first year dealing with these guys. Do they appear every year? Or do they only show up when the summer's relatively cool and moist?

Gaia gardener said...

From what I understand of the biology, I don't think that replacing the soil or turf would make any difference at all. It's the aphid feeding on the tree root that feeds the fungus.

Sean said...

Removal of the tree is not an option! Not only is it healthy, it's the neighbors!! But these mushrooms can also thrive on decaying wood as well as the nymphs. Due to past owners, my yard has plenty of old sticks deep in the grass. I also have removed lots of dead roots from a tree long gone. I think it was a White Ash. So... I think my problem is excessive, contaminated(with spors), decaying wood material. Turf replacement may be a the only good solution. But I will wait until this winter before I get drastic.

Anonymous said...

I have the same issue in our front yard. We didn't want to eat them, as I used fertilizer w/weed control, Didn't want to take the contamination risk. Maybe next year I'll skip the fertilizer, and see how it goes. If they come back, I'll try them then.

Gaia gardener said...

The descriptions of their taste ("dirt-flavored") didn't sound very appetizing to me. I think I'd have to be starving to try eating them!

jo said...

These spread rapidly. I first noticed them about 3 yrs ago, and now they are not only around the Ash (killing them), but near my apple tree and blue berry bushes and elm. Instead of 20, there are perhaps 150 now. They have not yet approached the maple not pine. I have cut them down repeatedly with the lawn mower to no avail. Since a strong bleach and water solution will kill mold/fungus, I have just spent an hour spraying this mixture on EVERY brown bolete! If this doesn't work, I will try a strong weed killer, one that travels through the plant and kills the root. Will let you know. Has anyone else tried anything? Sep'10

Gaia Gardener: said...

We've had a dry summer this year and I haven't noticed any of these at all, so I have to assume that weather conditions are extremely important in their formation. Since they are a fungus that spreads deep in the ground, I'm not sure that there's any way to get rid of them, short of cutting down the tree.

Anonymous said...

I ate quite a few of those in Michigan. They are fairly tasty, especially in a stir fry or with eggs. I'm not sure where the "dirt" description came from. They change color when chopped, but freshen up again when fried. To the person who was planning to put plant killer on them: DON'T. The fruiting body is only a small "tip of the iceberg"; besides, it is unlikely plant killers would be effective against fungi. You would turn your yard into a toxic waste site and kill everything except the mushrooms. Keeping the mushrooms picked will slow their spread, but they aren't that much of a threat to the trees anyway--better to coexist with them.

Sue said...

We planted 24 ash trees many years ago on our property and now the lawn under these trees is full of these mushrooms which I would very much like to get rid of. Right now I just mow over them and hope I am not helping them to spread. Hope they and their aphid friends don't kill my trees.

Gaia Gardener: said...

I have to assume that climate conditions have a lot to do with their formation. I've done nothing since this post and I haven't seen any more, either last summer or this summer. Both summers have been fairly dry, though.

Corner Gardener Sue said...

Hi Gaia Gardener,
Someone in the FB group, Gardening with Nature in Mind posted a link to this post. He thought it very cool to read about the relationships between the mushrooms, trees, and insects. It was also discussed in the group how people automatically want to get rid of such things instead of coexisting with them.

I have had different kinds of fungi/mushrooms in the area where we had to have a silver maple cut down a few years ago. They come and go, and I've only hoed a few that were crowding some of the plants.

Anonymous said...

These are all over my rural home's yard. We have a variety of trees many of them being Ash. I personally have no real issue with them, in fact I'm pretty excited to learn that they are actually edible! Can't wait to try a few. Since I live in the country I don't have any interest in having a perfectly manicured lawn, just as long as it gets mowed, I'm good with all the weeds and mushrooms that provide sustenance and medicinal value as well as biodiversity. For those who wish to rid their manicured lawns of them, I would suggest a FUNGICIDE. Hello? They are fungus not insects or plants.

Gaia Gardener: said...

Well, I'd be VERY careful in trying them out based on the primarily internet research I did. Plus, they aren't supposed to taste very good - the line between edible and tasty can be a pretty major one!

I love your willingness to avoid a perfectly manicured lawn - and that biodiversity is important to you. We need to recruit others to our "attitude army"!