I've had this Thuja for approx 3 years and over the past 6 months it has progressively lost 1 or 2 branches at a time. The edges turn brown slowly and die (as in photo) then it seems to effect another branch. I've tryed various sprays as I've been told it could be spidermites, fungal disease (but no one I've asked is very familiar with Thujas so they're not sure) and it seems to be continuing. Can anyone accurately identify whats doing this so I can sort out how to stop it?