|Azolla filiculoides, March 2018|
Oh no! Water Fern is a problem:
"Water fern can achieve 100% cover over the water surface as a carpet occasionally up to 30cm thick. At such times, it blocks out light, preventing photosynthesis in aquatic plants and preventing or compromising oxygen diffusion. It also prevents amphibians and invertebrates from reaching the surface and may disrupt movement of animals on the water surface"
GB Non-Native Species Secretariat
This is a highly sensitive area, Woking Palace is a Scheduled Monument and Old Hall Copse is Ancient Woodland so a sensitive solution was called for. The best way was to introduce a North American,weevil, Stenopelmus rufinasus. These tiny creatures love eating Azolla, so much so that's all they do eat.
|Stenopelmus rufinasus - Photo CABI|
Eventually, the day came when the weevils were released. In July, assisted by the Chair of the Friends of Woking Palace the weevils were let loose to do their work. But there was a hitch. By the time the weevils arrived, the extremely hot, dry weather had dried up most of the moat and the Azolla along with it! Far less of a weevil feast than anticipated. Nevertheless, we hope that one way or another the fern will not make a reappearance in 2019.
If you'd like to see my detailed photo journal of the story of the Fairy Fern you can find it at:
You may also be interested to see:
CABI Azolla Control