A pest that caps them all
TOADSTOOLS are simply fascinating, scientifically speaking. The familiar caps-on-stalks are only part of a much bigger threadlike organism that lives entirely underground, sending up the familiar parasol structures to distribute their microscopic spores.
But for lawn-lovers the annual invasion is about as welcome as a rash of molehills.
The main culprit in cultivated turf is Marasmius oreades. This is the toadstool that forms the classic persistent fairy ring, a yellowish circle of sickly-looking grass surrounded by an edging of longer lush green grass containing small buff-coloured toadstools.
Fairy ring champignons can be present from late spring to the first proper frost but in hot summers they shrivel up, leaving wrinkled brownish caps that rehydrate shortly after a light shower. It’s a great identification feature.
In a dry season Marasmius caps may vanish for months until autumn rains bring your fairy ring back again, and it keeps growing steadily bigger.
Each new generation of toadstools moves forward into fresh ground, where the “roots” free up nitrogen from organic matter in the soil. This is why the grass briefly grows greener round the edge of a fairy ring, leaving it yellow in the centre where the ground is exhausted.
Large ones in undisturbed grassy places such as churchyards may be centuries old. Puffballs can behave the same way but are more often found in village cricket pitches.
However, in autumn, which is prime toadstool time, you may also find all sorts of other toadstools popping up in a lawn. Mostly they are “little brown jobs” that are difficult to identify but sometimes you’ll turn up real oddities.
Some are associated with nearby trees, where the fungus lives in a symbiotic relationship with the tree roots. The red and white spotted fly agaric, for instance is always found close to birch trees, so if you have a woodland garden you can expect to see a lot more fungi than urban gardeners will.
What’s to be done? Well, not a lot to be honest. Weedkillers don’t touch fungi. The most effective remedy, which was once widely used for fairy rings, was to dig out the affected area two feet deep and one foot wider all round, then refill it with fresh topsoil and hope you’d “got it all”.
Yet the thing about seasonal species is they disappear on their own come the first proper frost and in the “wrong sort” of year you may not see them at all. Even if you do, they are very short lived, only lasting a few days.
If you want to get rid of them fast, the easy answer is to run the mower over the grass, whether it needs cutting or not, just to deadhead the beasts.
But why bother? Think yourself lucky. You couldn’t buy a real live fairy ring or fungi for love or money. In today’s natural, wildlife-friendly “green” garden, a few toadstools make the finishing touch.
And if you want to play croquet, clock golf or practise your putting, well, just wait another month they will go away again all on their own.