Identify Turfgrass Diseases – Fairy Rings
Turfgrass Diseases – Fairy Rings
The legend attached to ‘fairy rings’ is much more attractive than the real cause. The legend says that the circle of dead grass is caused by the feet of gnomes and fairies dancing round the fairy queen throughout the night, killing the grass with their feet. To compensate mortals for this damage, the fairies make the grass grow thicker and greener. The fact is that fairy rings can be caused by not just one fungus disease, but by several. Mushroom-like fruits appear and whilst most of them are harmless, one of them, Lepiota morgani, is deadly poisonous if eaten.
So to be on the safe side do not let children, or indeed anyone else, eat any of the little fungi which appear. Sometimes animals, particularly puppies, will gobble these up usually without any ill effect. But my advice is remove or destroy them with a brush or long cane whenever they are seen.
Fairy rings, which is one of the common turfgrass diseases, usually appears as circles or other shaped areas of dark green grass in lawns that are normally on the moist side. A ring of dead grass may develop on the inside or the outside of the greener circle.
During dry weather, especially in late summer or early autumn, the dead area is usually outside the green ring. The following spring, whilst theis still moist, the fungus occupies the soil outside the dead ring and there the growth of the grass is stimulated and dark green in colour. In addition, a second ring of green is sometimes seen inside the dead ring. After rain or heavy watering the mushroom-like fruiting bodies of the fungus which causes the disease may appear in the circle of green grass.
The first thing you see are tufts of stimulated green grass or maybe a cluster of mushrooms, depending on season and the amount of organic matter in the soil. Theand mycelium grow only outwards from the central cluster in the surface foot or so of soil. Actually the advancing margin of the fungus is actively growing, the receding margin dying. The stimulation that shows up as greener grass is due to the increased amount of nitrogen which is made available to the grass by the fungus as it breaks down the organic matter in the soil. It uses up moisture to do this and so the soil in the dead area is usually drier and this contributes to the death of the plants.
Some fungal diseases are peculiar to some varieties of grass, often first starting on one type and then spreading to others, while others are universal killers such as the fairy ring fungus. How to get rid of fairy rings is a recurring question and it must be said straight away that there is no complete answer. One of the biggest problems of course is the depth to which the fungus penetrates which may be as much as 15 to l8 inches but is, more generally, about one foot. The only sure way of getting rid of it is to excavate to this depth and then fill in with new soil; this, in my opinion, is not worth the trouble. A professional way of masking the accentuated green of the fairy rings is to make all the other grass look the same. This can be done by applying either a foliar feed of nitrogen or use some quick-acting stimulant such as nitro-chalk.
Another device I have used is the sub-irrigator which is merely a metal tube inserted in the end of the hose pipe. With this you can bore holes to a considerable depth. This is in fact, a technique I use for watering shrubs without wetting the surface of the soil. Provided you use a container with a non-return valve you can inject suitable fungicides into the soil by this method. Jeyes fluid, Bray’s emulsion and permanganate of potash are all safe controls I would recommend.
It is possible to strip the turf from the infected area, break up the soil and saturate it with fungicide. However, I do not recommend this as the time of recovery is even longer and the damage more marked than if you let it alone.
Although the fairy rings are more pronounced and may be more irritating on a perfect sward, they are really less damaging than some of the less spectacular fungal diseases such as fusarium and red thread. I am a bit of a grass fanatic, but personally I still like to think that it is the fairies and not a nasty fungus which is responsible for the rings.
When making a new lawn avoid burying wood chips and tree and shrub roots, as this can encourage the disease.
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