Hello - I am plant sitting a friends indoor apple tree. The tree has had little gnats in its soil since the fall. We've tried everything to get rid of them. SOS pads on top of the soil, so when the tree is watered the soap kills eggs, gnat spray from the hardware store, soap and water in a spray bottle, hydrogen peroxide and water, I think I tried vinegar and water too. I've been told that the tree needs to be pulled out, the roots need to be washed and the soil should be replaced. I don't think its a good idea to re-plant the tree in mid-winter. FYI I'm in the Dawson City, Yukon Territory in Canada. Do you have any suggestions or advice for getting rid of soil gnats once and for all? Thank you kindly, Marina