EXPERT TIPS Fungal fanfare Mick Lavelle is senior lecturer in horticulture at Writtle University College*

Extra-large Chinese money plant

Many plants are dying back in November, but on the ground you can encounter the seasonal ‘flush’ of toadstools that reach their peak during mid to late autumn. These are often a cause for celebration, not concern.

Toadstools and mushrooms are usually the only visible part of a fungus that is performing a useful role in the garden. As a general rule, fungi that are harming plants generally appear connected to them – emerging from the stems or branches. Those emerging from the ground are more likely to be either saprophytes – decay fungus – involved with the breakdown of dead organic matter into useful plant nutrients, or mycorrhizae - root symbionts - that help to protect and supply plant roots with nutrients. Both are a sign of a healthy soil ecology.

There are exceptions, and chief among these is the honey fungus, which attacks and kills otherwise healthy trees and shrubs. These are usually very distinctive, when dense clumps of honey-coloured, wavy-edged toadstools appear briefly on, or right next to, infected stumps in autumn. There is no cure once a plant is affected, and you will need to remove the stump to prevent it from spreading.

The most iconic toadstool is the fly agaric, whose red cap covered in white spots is almost universally recognisable. You usually see these around birch or pine species, which they supply with scarce soil nutrients in return for sugars. Far from damaging the tree, they are vital to its continued health and wellbeing. So don’t reach for the fungicide when you see a toadstool – you may well be doing more harm than good.