I have around 10 conifers to the rear of my garden and 3 of them are starting to discolour around the bottom can you tell me what is causing this and how to treat it.
Conifers are often self suppressing i.e. the top growth shades out the bottom growth causing it to die off. No treatment, just a fact of life. Failing that you have got to consider root or foliar disease and diagnosis cannot be given on such a brief description. You need to get an arboriculturist or horticulturist to look at them.
I have the same problem and I found out that it was cats doing their business around the base of the tree, discolouring the bottom foliage in the process
I wrote earlier in the year that we have conifers which have died off in patches through the centre and towards the tops of a couple. They are still growing green at the top and bottom. I was wondering if it was an aphid of sorts.