I've recently built a new pond, and started introducing various plants. A healthy water hawthorn plant was introduced about 6 weeks ago, and started sending up new shoots quite quickly. Patches then started appearing on the floating leaves - the leaf tissue appears to be being grazed off, leaving just the leaf skeleton. All the leaves have now practically disappeared leaving just the stalks and the flower stems.
My first lily leaf emerged last week and that appears to be suffering the same fate.
I have no fish or snails in the pond (that I'm aware of!) just tadpoles. There are no apparent signs of insects on the underside of the leaves etc.
Can anyone tell me what is causing this damage, and how do I stop it ????
Many Thanks