Michael Henderson suggests

Email registration

Free weekly email update

Great products and special offers for Spectator readers

Click here for great value events

Click here for exclusive articles, offers, tasting notes and discussion

Gardens

Ursula Buchan

Wednesday, 15th October 2008

Magic Mushrooms

We can all think of discoveries, which made little impact at their first introduction, but which changed the ways people worked or lived for ever, nevertheless. Charles Babbage’s ‘Analytical Engine’ of 1840 must be the most strikingly impressive example of this. But I think I may have spotted one in the gardening sphere as well, with the recent harnessing of a scientific discovery of 1885. That discovery concerned the role of mycorrhizal fungi in the soil.

When, some five years ago, I first sprinkled some rootgrow (yes, I know, proper names put in the lower case is annoying and unhelpful but it’s not my fault) in a hole in the ground, before planting a tree, I did so in a spirit of mildly sceptical scientific enquiry. I was intrigued by the ingenuity of scientists at a Kentish firm, PlantWorks, who could turn several strains of native mycorrhizal fungi into granules and sell them at a reasonable price, but I was not convinced that these would genuinely make a difference to how quickly my tree established itself in an unfriendly clay soil.

I certainly did not predict the tremendous impact these ‘friendly fungi’ have had on promoting rapid growth in hostile or disturbed soils and on helping to beat that traditional bane of gardeners, rose replant disease. So startling has been rootgrow’s progress, in fact, that, only eight years after its launch, the Royal Horticultural Society has just endorsed it.

When I first came across rootgrow, I knew a little about mycorrhizal fungi, since they have been studied over many years by horticultural scientists, and are in all the textbooks for professional gardeners. I knew that a symbiotic relationship exists between these fungi, with their network of thread-like filaments (hyphae), and plants, whose fine root hairs they colonise or surround. The plant ensures that the fungi get sugars, which they cannot manufacture themselves without chlorophyll and sunlight, while the hyphae exponentially increase the surface area of ‘roots’ for the uptake of water and soluble mineral salts, especially nitrates and phosphates. (It has been computed that there are up to seven kilometres of filament in seven kilograms of soil.) In woodland, this secondary root system forms a kind of root intranet betwen adjacent trees, so that the nutrients are shared throughout the plant community.

1 | 2 Next page