I have a phal with 5 leaves that I purchased 5 months ago. It is about to reflower when I noticed the new leaf growing from the tip of the plant is starting to rot. The end of the leaf is yellowed and the base is black. The other leaves are still firm and green and I've checked the roots...they appear healthy either green or tan but firm. I want to cut off the dying leaf, but as it's the terminal leaf I'm afraid no more new leaves will grow and the plant might die. Please advise.