HONEY FUNGUS CONTROL

I believe that I have a method of controlling or suppressing Honey Fungus (armillaria) in the garden environment. This method does not involve spraying fungicides everywhere or decimating and digging up half the garden's woody shrubs and trees if Honey Fungus is noticed.
The method I am trying is a biological control using Orchids to keep control of an established infestation of Honey Fungus. The Early Purple Orchid (Orchis mascula) has an association with species of Armillaria, some might find it strange that a delicate plant like an Orchid could have a symbiotic relationship with a known parasitical fungi. However after some preliminary study of the way orchids control their fungi hosts it seems to be all one way traffic as far as nutritional requirements go. I believe that the Early Purple Orchid takes control of the fungi and in some unknown way reduces this ravenous parasite into a meek saprophyte. This, I believe, it needs to do because if the Armillaria fungus attempts to attack a living tree, the tree defends itself by manufacturing chemical defenses which the fungus will absorb, and due to the metabolism of fungi, pass these poisonous chemicals along it's length which could harm the feeding orchid, as the orchid is in turn tapped into the fungis nutritional transportation and metabolism. This is a necessity of survival as far as the Early Purple Orchid is concerned. I am also aware that the trees true symbiotic partners also defend the trees roots with their own armory.

I was asked to investigate a friends Fatsia Japonica which had been observed as having fungi fruiting bodies on the ground near the butt. The Fatsia had three stems rising off a single root stock and all three were about 8ft tall. The description of the fruiting bodies sounded like Honey fungus, but as the garden was in North Wales, nearly 300 miles away it took a few weeks before I could investigate in person.
My first inspection took place in early April 1997, the Fatsia was in a walled garden with good shelter and was growing on the edge of the tree line of a large mature Aesculus Hippocastanum (Conker Tree). Although there were no complete fruiting bodies for me to inspect there were some large fragments that had the appearance of Armillaria, but the clinching proof was the sheet of mycellium under the bark low down on one of the Fatsia stems which also had a mealy smell. All of the latest foliage growth on the Fatsia was showing chlorosis and the leaves were smaller than one would have expected, as I had only been asked to do an inspection I prepared a report but was concerned that to grub out the Fatsia may damage the roots of the Conker tree which would definitely encourage infection of the mature tree, although there was a good possibility of Armillaria infection in any case. So initially I prepared a wood ash tonic and watered it in around the Fatsia and I gave my recommendations to the gardens owners. In July 1997 I revisited the garden to find that the infected stem was dead and had a small tuft of Amillaria fruit bodys and the wood had a bit of string rot, however the other two Fatsia stems had the appearance of good health with no chlorosis colouring at all, this I attributed to my "Tonic".

I got the go ahead to proceed with my suggested Orchid treatment in November 1997, I purchased 5 in March 1998 and planted them the same day. (the fatsia had lost another stem since my previous visit) These orchids are quite rare but I was able to purchase them from a supplier in South Wales - John Shipton Bulbs bluebell@zoo.co.uk) tel:01994 240125. Although planted late all 5 plants went on and flowered and 3 possibly 4 re-flowered in Spring 1999. I planted them in between the Fatsia and Hippocastonium, in the hope that either these parent plants would tap into the local Armillaria or that their seeds would.  With no other guidance all I could do was to try and emulate the actions of Nature. I intend to re-visit to inspect the garden in Spring 2000, the gardens owners have not reported any re-infection of the Fatsia as yet. Here you can see a photographic record of the site.

I have put together some general instructions for those who want a simple method of checking for Armillaria infection here and for those who would like to investigate these ideas further please visit our Mycorrhizal links page to read the latest discoveries and knowledge. 

Note: 2011: The Aesculus Hippocastanum Tree did not get attacked from the Armillaria and is still in good health now after twelve years.

1. This is the wood ash plant tonic that is better then anything you can buy for bringing your Trees and Shrubs back to robust health.

2. This is a list of poor gardening practices that encourage Honey fungus to attack your plants.