Hello all, I'm a very novice gardener so looking for some basic, easy to understand advice here. One of my 3 olive trees, not potted, has for the past several weeks been showing signs of distress. There was initially some yellowing and leaf curl, along with some black spots on the underside which I have treated with copper (appears to have largely worked), but now the symptoms have spread more broadley, with leaves going brown and curling across the plant. There has been no new growth for the past few months whilst our other trees have gone great-guns. Thinking it's a problem with the roots. Have treated with Yates anti-rot several times directly to the leaves, and also turned over the top soil (adding further premium mix). No obvious results yet. Any advice on what else to try or how long to expect results? Some yellowing leaves now noticeable on the adjoining plant.