I have recently purchased a Standard Kitchen Bay Laurus nobilis, once I got home I noticed some discolouration (black spots) on the leaves. Is this a disease? do I need to remove the affected leaves or treat in some other fashion?
Frankly, if you've only recently bought it, I'd return it from whence it came. Bay is prone to black spotting, particularly when it's in pots, and particularly in damp weather. You can try spraying with an antifungal spray, but then you won't be able to use the leaves in cooking, and most treatments of this kind are relatively ineffectual. Obviously, damp, chilly weather is prevailing throughout most of the UK currently, but it could also be something much more serious such as anthracnose, though its unlikely. Nonetheless, I wouldn't expect to see this on a newly purchased plant, particularly given the price of standard Bay trees.