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HONEY FUNGUS |  |
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A New Look at an Old Enemy - Armillaria mellea Like most things in life Honey Fungus has its good points and its bad - without its presence in the environment the surface of this planet would probably be piled high with the corpses of trees. Honey Fungus is prominent among the wood decaying fungi in rotting these down and returning their nutrients to the soil to assist the new growth of future generations of trees. Just as jackals, hyenas and vultures scavenge and clean up carcasses in the jungle, Honey Fungus saves us time and money by causing the biodegradation of dead wood - it reduces the lignum and cellulose to glucose which insects can then digest. If it confined its activities to this beneficial service to the environment everything would be fine but unfortunately it does not - it also has a very nasty side to its nature in that it also attacks adjacent woody subjects. In a woodland situation this tendency is limited by the presence of many antagonistic fungi but in our gardens it has unrestricted opportunity and it sends out underground rhizomorphs to take advantage and carry out this lethal work. However, if you can persuade the invasive rhizomorphs to veer away from the vulnerable lateral roots of potential victims and instead to surface and sporolate, we shall not only save those subjects but we shall encourage the hitherto pathogen to produce sporophores, which will release more spores into the atmosphere, which are saprophytic (they cannot harm the living woody subjects, they have to land on dead wood to germinate) and the crops of mycelia they produce will help to biodegrade more dead wood in new sites. We can achieve this required deflection of the rhizomorphs by treating protectively our
trees and shrubs in the area of risk by applying Armillatox
solution around the collar two or three times a year in the way illustrated
 It makes biological sense since you are organizing your adversary to work for you using materials produced by once living trees and shrubs. Some of your Questions about Armillaria Mellea
What is Armillaria?
Armillaria mellea or Honey Fungus to give it its common name,
is the most pathogenic of a genus soil borne fungus,
the other races being, A.obscura A.ostoyae, A.bulbosa and A.tabescens.
Armillaria Mellea is so called because the caps of the sporophores
(mushrooms) are scaly like an armadillo and honey coloured (mel being Latin for honey).
People say you cannot cure Honey Fungus - "dig 'em up and burn them"
That inoculated trees and shrubs have been cured is a statement we can make without
qualification. However whether a given subject can be cured depends on many things
- the extent of the disease, the type of subject and the intelligent use of the material
etc. How do I know if I have Honey Fungus?The positive evidence of infection by Honey Fungus is the presence of established mycelium between the bark and the cambial layer in the lateral roots - you have to excavate back and look under the bark on the lateral root facing the suspected source, a pen knife is usually sufficient to carry out this exercise. Mycelium is a collection of delicate white threads (each thread is termed a hypha) looking rather like a thin covering of cotton wool - it appears very white and has a characteristic smell of mushrooms.If, however, mycelium grows up the root and eventually reaches the collar of the tree or shrub, it will then block the vascular bundles up and down which transpiration travels circumferentially. With this blockage in 'the plumbing', the subject, when under stress (conditions of drought) will operate its defence mechanisms and drop its leaves away from the sun in order to reduce the transpiration losses. If this is insufficient it will partially defoliate and if this is still not enough it will completely defoliate prematurely.
What are Rhizomorphs?After the mycelium has colonized most of the dead wood under ground, the hyphal strands form together to make a thread, which is called rhizomorph. This 'vector' (carrier of disease) travels close to the surface in compact soil but lower down in broken, open soil, its target being the lateral roots of another woody subject and when it finds this new victim it pushes its way through the protective cork or bark on the root and so inoculates this new host with Honey Fungus. The rhizomorph is strong enough to push through thick polythene and even severed from its source, this 'umbilical cord' will survive and continue its mission. Although it likes 'fresh meat', a healthy woody subject that has been treated prophylactically with Armillatox will cause it to turn away and surface.
I know I have Honey Fungus but I cannot find any rhizomorphs !After rhizomorph has inoculated its victim, its remains are difficult to see and identify from a root section. If both are dropped into a bucket of water the rhizomorph floats and the root section will sink but you will soon learn to identify rhizomorphs by 'stretchy', elasticity feel and brown/black colour is another 'give way'. If you are lucky enough to catch a live one before it strikes a victim, it is luminous in the dark. In medieval times they lit hay barns with clusters of them and roots covered , with them were considered to have medical power and these were the original magic wand.
How did I get it, and what should I do about it?Honey Fungus in a garden originates from a dead stump or the buried lateral roots from a tree that has died from Honey Fungus or been felled some years before. Unfortunately when a tree is removed from a garden, more often than not, it is sawn off across the base rather than pulled over which sprags up the lateral roots - the roots left being the food supply for the pathogen. Once you have this situation, where you have inoculated roots underground there is often very little you can do about it, as removal of these roots may be extremely difficult, expensive and if they are cross rooted with other lateral roots form surrounding health woody subjects, removal would cause abrasive damage to these latter. If nothing is done then there is a risk that the disease by means of its very efficient rhizomorphs travelling through the feeding soil (from the surface down to clay) may now claim new victims. Our philosophy is to stop this by persuading you to treat prophylactically all your favourite and valuable subjects in the area of risk and continue every year until the Honey Fungus in the source is starved out.
How do I treat my woody subjects?
To treat a subject prophylactically ( or remedially, curatively for that matter), we require you to water around the collar (where the lateral roots meet the trunk) with a solution of this fungicide as per the instructions in the supplied booklet, dependent on whether you are treating a tree or shrub. Take the rose off your watering can so that you can rest the spout against the trunk and run the solution down the trunk and saturate around the collar. Effectively you are making a poultice around each end of the lateral roots. A multiplicity of light applications is always preferable to a heavy single drench, especially after maximum leaf development i.e. July through to defoliation. Armillatox is very penetrating (rather like WD40) and it works its way through the natural fissures in the bark covering the lateral roots and is eventually picked up on the phloem, which is on the outside of the cambial layer. Fortunately the transpiration in the phloem is downwards (as opposed to the xylem further in, where it goes upwards) and this transpiration carries the fungicide and distributes it through the root system i.e. it is phloem mobile. This way we hope it will purge out any established mycelium that may be between the bark and the cambium and also that it will afford prophylactic protection from inside the root against invasive rhizomorphs. This treatment may be carried out at any time with an evergreen subject, but with deciduous plants it should be done when they are in leaf.
Are there any signs I should look for?Hney Fungus prefers to reproduce itself by means of the highly efficient rhizomorph and if you are successful in stopping the pathogen claiming any new victims your adversary will adopt another strategem to reproduce and will sporolate vigorously i.e. you will get larger denser clusters of sporophores than ever. Nature not being wasteful, Honey Fungus reverts to its secondary method of reproduction, which is to come to the surface and use the fruiting bodies to shake spores through their gills into the air and blow away and if they are lucky enough to land on dead wood, being saprophytic, they will germinate and eventually colonise the new site. To you they are not dangerous if you have no dead wood around. Indeed, they are a good sign that you are starting to win your battle against Honey Fungus.
Is there an 'upside' to the 'downside' in treating Honey Fungus?After, perhaps a year or two that the apparently healthy subjects, you are treating prophylactically, will burgeon with health, this is because those subjects are being relieved of the debilitating effect of any disease.
When a host plant is attacked by a parasitising micro-organism of any kind it produces
its own anti-bodies in response to the attack - a potato produces alkaloids in its skin to
ward off eel worms, the tobacco plant produces nicotine to discourage insects, castor
produces ricin, which poisons any predator and so forth.
If I remove a tree or shrub that has been killed by Honey Fungus can I plant a new subject in its place?
Oddly enough the answer is yes. Certainly the new planting hole needs a thorough drenching
with Armillatox at a dilution of 50 to 1 to purge any
mycelium, but the important point is that the deadly rhizomorphs are heading off in a
radial direction away from this centre leaving it to become a relatively safe position in
such an area. Doesn't it make sense to at least try tree medication before tree surgery?
Even if you do not manage to save the tree, the hole left would have had to be sterilised anyway. | |||||||||||||||
