Okay a received a cutting about a week ago, but then had to go out of town...and was not able to deal with it. One of the tips looks like "black tip"... not really sure. It has started spreading downward and I think needs to be dealt with.

Here's my question. I understand cut until I get good clean meat but should I cut it at an angle or straight across? After the cut should I callus the cut just like a regular cutting, and then should I seal it.

Any advise would be great.