Pine weevil nematodes
I live on a new estate and recently discovered that our lovely 40' pine tree was buried in clay subsoil to a depth of more than 30 cm. Over the last three years or so since construction, adventitious roots have grown up into the soil and we also have girdling roots. As the tree has a TPO, this requires permission from the District Council and a tree surgeon to cut the harmful roots. However, we also found pine weevil larvae (I think) in a small piece of bark that fell away and have dark soft patches of rot all around the base of the tree. It's easy to tell the original ground level (a golf course) because there is a distinct layer of rotted down pine cones and the soil changes. Can I treat successfully with nematodes, when should they be applied and how often and are there commercially available nematodes that could do the trick. I have never used chemicals before in my garden but I think that ant spray would do the job if we can't find an organic solution. Would spraying with ant insecticide (cyclomethrin) or using nematodes constitute 'work on a tree' or would we be able to just get on with this ourselves?