Panic reproduction of macrofungi and trees

[Fungus]

Sean asked me to elaborate on the subject of "panic fruiting".

Once a tree is no longer capable of defending itself against attacks of biotrophic or necrotrophic parasitic macrofungi and "foresees" it is going to die and/or fall soon, the tree often resorts to "panic" or survival reproduction by producing as many seeds as possible, which mostly results in about 70 % of the seeds being sterile. If as part of a tree species specific time cycle, the seeds however are over 70 % fertile, it indicates, that the tree is in such a good condition, that it can afford itself the "wealth" of massive reproduction.

If the tree has ectomycorrhizal symbionts, it will - while keeping all its stored energy to itself - "run dry" the mycelium of the symbiotic partner to uptake as much nutrients as possible, with which the symbiosis, which in effect is a state of balanced parasitism, turns into one sided parasitism by the tree.

If on the other hand the mycelia of the ectomycorrhizal macrofungi "notice" a diminishing supply of sugar by the tree, they sometimes also "panic fruit" with extremely big or an extreme quantity of fruitbodies to disperse as many spores as possible as long as the tree "permits" them to and they can even fruit "out of season", f.i. in June, weakening the tree even more, instead of in autumn, when the energy reserves of the tree are at their peak.

In evaluating the phenomenon of massive fruiting of ecomycorrhizal symbionts, one should always also look at the condition of the tree, to determine whether the tree is in such a good condition, that it can afford to share so much of its energy reserves, or is in poor condition, indicating that the mycelium is panic fruiting.

The same phenomenon can be seen with biotrophic and necrotrophic parasitic macrofungi living on/of trees. When the mycelium of a biotrophic parasitic species "foresees" the forthcoming death of the tree, it too can resort to panic fruiting by producing as big and/or as many annual fruitbodies as possible, which f.i. can be seen with Pholiota squarrosa and Meripilus giganteus. Sometimes both the annual bracket fungus and the tree "panic fruit' at the same time, as can be seen in the photo of a Castanea with L. sulphureus.

Once the "food" or cellulose supply of the tree diminishes, perennial brackets producing necrotrophic parasitic macrofungi form thinner and retracting layers of tubes on top of the old layers (photo Salix with Phellinus igniarius), indicating they are slowly "starving" and the tree is about to fall, after which they live on as saprotrophic recyclers of the trunk with soil contact.

Another indication of the mycelium of a necrotrophic parasite being in its end phase of wood decay, can be panic fruiting with poorly developed, (partially) sterile annual or perennial brackets or lumps (photo Daedalea quercina) or the massive fruiting of an until then only with rhizomorphs present Armillaria species, once the tree is felled and nothing but the stump remains.

---

Edited May 22, 2011 by Fungus

[sloth]

Don't know if this should be in your q&a, but is it only ectomycorhizea which are macrofungi, or are there endomyco's which produce 'mushroom' fruit bodies too?

[Fungus]

... is it only ectomycorhizea which are macrofungi, or are there endomyco's which produce 'mushroom' fruit bodies too?

 

Only a specific group (20 %) of macrofungi is capable of forming ectomycorrhizal structures on/surrounding roots of a specific group of tree species and of producing above ground fruitbodies (except the truffles), all other tree species (and almost all green plants) depend on endomycorrhizal symbionts, a specific group of microfungi, which asexually reproduce with spores directly formed on the mycelium and mycorrhizae in the soil.

Also see : Mycorrhiza.

---

[Tony Croft aka hamadryad]

this explains davids lab stumper to a T, excellent information.

[sean]

Thanks for quick response.......will have a read in a bit.

[David Humphries]

What can happen in a year...............

 

 

Gymnopilus junonius, fruiting on Crataegus from last year.

 

 

 

.

[David Humphries]

Same tree, one year later...........

 

 

Tree just about still functioning, but not next year

.

[Fungus]

Same tree, one year later ... Tree just about still functioning, but not next year.

 

David,

Great documentation of the phenomenon of panic fruiting .

[Tony Croft aka hamadryad]

cracking shots david.

[David Humphries]

No beter place to share our findings & observations !

 

Arbtalk reaches the parts other sites can only dream of

 

 

 

.