Hello all, I have a set of recently planted “Fine Line Buckthorn” plants (not invasive but a hybrid) of Botanical Name: “Rhamnus frangula 'Ron Williams'” (see photos). In a matter of 1-2 days most leaves turned yellow/brown with pinhole size holes (photos). I also found 2 beetle-type insects (don’t know exactly what they are) on a leaf (also took photo). I appreciate wholeheartedly if any of you have insight into what may be causing this and, more importantly, what I could do to remediate and hopefully bring back these beautiful plants to their healthy state. Thanks in advance.