Horsetail – Equisetum spp., approx 30 varieties. The one which grows in our allotments is probably Field Horsetail (Equisetum arvense), although it may be others. It likes damp/wet/marshy ground, but can establish in any heavy dampish ground. It reproduces by spores produced by short brown shoots early in the season. What we normally see is the familiar (Christmas tree shaped) green shoots.
Mare’s Tail – Hippuris vulgaris, although similar in appearance, is a water/pond growing plant. It will produce flowers and is not normally seen on the allotments.
Horestail is notoriously difficult to eradicate, once established. Any small piece of their spindly black root will re-establish as a plant, and their roots can, apparently, go as deep as 8 feet.
If you are unlucky enough to import pieces of root in a topsoil or compost dressing – weed it out every time it appears above soil. This should prevent it becoming established. Control of established horsetail is best done by digging/forking through the soil when it is in the right condition: i.e. not too wet and sticky! Once you have removed as much as possible, any that shoots is easily dealt with. Before it reaches 3 ins/7cm high, hoe off an inch below the surface.
Eventually the food supply in the root is exhausted. Let it get bigger than stated and food begins to be stored in the roots again, and round and round you go ad infinitum. Never touch Horsetail with a mechanical cultivator. If you do you will understand why it has been around for 60 million years!
For more information about horsetail go to the GardenOrganic website.