Purple tips on bud leafs?

Temps dropping to or below mid 60s F? That'll do it. Looks like autumn colors in this picture. If temps are fine, i'd still lump this in with senescence. When i look at diary i see some more leaf symptoms. May need a little more N in your mix? yellowing from tip-in and from bottom-up... Though the necrotic portions could be something else if showing up long before end. Check runoff pH and ppm, if you can. if not high, look over labels of what you feed. Try not to impact ratio too much while adding a little N. Think the hints of red/purple coming in are simply temperature or just how that plant ages. some really exotic colors and patterns can occur naturally. Remember, you have a lot more information to use than what is given here, since you've been taking care of this plant day-to-day. It is easy to suggest wrong thing with incomplete information. unfortunately, we are always working with a little lack of info no matter the context.