Question
The leaves of my weeping willow have, in the last two weeks, turned yellow and are all falling off. No obvious bug infestation. Any idea as to why this is happening?

Answer
Hi Steve..if you do not see bugs then it could be you need to water more.  Yellow leaves are either bugs or not enough water.  If it is not a water issure then you will need to spray with a insecticidal spray.  I use Neem Oil 100% pure.  It is safe and absorbs into the leaf so the bugs will not eat it or suck on it and go else where.  It does not wash off and it totally safe.