Leaf Drop on Begonia
I have a Clown Begonia (Begonia Maculata Wightii) which I purchase from the internet. Since I received it about 6 weeks ago it has put out about 5 or 6 new leaves. Once a new leaf gets to be 2 or 3 inches long it falls off the plant. Most of the time the end of the leaf is a clean break. Sometimes with the smaller leaves there is a pink ring around the base of the stem. This constricts and then the leaf falls off leaving a hollow stem end at the pink ring. Any suggestions as to what could be the problem?