When the Disease Is More Valuable Than The Tree

I received an e-mail from a friend recently containing some pictures of rather shockingly large mushrooms that grew from the base of one of his stately oak trees following a large rainstorm. He wanted to know what kind of mushroom they were and, perhaps more importantly, if they are harmful to the tree. As you may imagine, the tree adds considerable value to his property. First off, let me tell everyone out there that when it comes to mushroom identification, I am no expert, and you should always seek the advice of an EXPERT before eating any mushroom that you are not sure of. The results of a poor choice in this area can range from gastric unrest to a horrible death. That said, I am can usually come up with a good guess. In this case, the mushroom bears an uncanny resemblance to a mushroom that is known to favor dead and diseased oak trees. It is a mushroom called Grifola frondosa, or Hen of the Woods. In Japanese (and many health food stores), it is called maitake.

There is good news and bad news about maitake mushrooms. The bad news is that it is definitely a facultative parasite. That means that it won’t usually attack a healthy tree, but it will happily move in to a sick tree and help hasten it to the grave. It is probably better than some other parasites, though, because it isn’t in any rush to finish off the tree. You see, maitake mushrooms are really good at fending off competition. They have even been known to push an established mushroom out of wood that the maitake is growing in to. Once the tree dies, the mushroom will continue to fend off competition and produce mushrooms from the stump for decades.

The good news about maitake mushrooms is that they are a prized mushroom, both as an edible and as a medicinal. Their ability to fend off bacterial and mycological competition for so long means that they boast a wide array of anti-bacterial and anti-fungal compounds that could have value to medicine. I have seen these mushrooms at a specialty grocery store twice. Once it cost $20 a pound, and the other time it was going for $30 a pound. Now, I don’t know how much each cluster in the wheelbarrow above weighed, but I’ll take a stab in the dark at 10 pounds. My friend did say that they were heavier than they look. So 4 clusters at 10 pounds times $20/pound. I get $800 worth of mushrooms that went in the compost. That is, of course, assuming my guess as to the variety is correct. It might not be.

But here is the thing: a mushroom is capable of turning each pound of dry wood into approximately a pound of mushrooms. That includes the roots. While this was certainly a bumper crop, this tree will likely produce smaller clusters of this mushroom several times a year for several decades. At what point is the disease worth more than the tree?

*Photo: Scott Shepherd