I'm not familiar with that variety's characteristics. The vendor is well known and to best of my recollection has a good reputation on this forum. Have you used any kind of sprays or treatments? How about your fertilizing and watering routine? Soil Conditions? I would assume if you have 25 other plants (assuming plumerias) you have a good system but thought I would still pose the questions. When you transplanted into the 7 gallon how did the root ball look? The tips look healthy from the pictures. I am not so sure that damp and cool nights could be a major factor. I would do two things...Make sure its not a something like a fungus or insect and start making some adjustments. Maybe relocate it in the yard to a warmer more sunny location or change your fertilizing routine to same quantity but in smaller, more frequent applications...monitor, adjust, and monitor some more. You can figure it out. Don't give up on it.

Some of the older leaves will get black spots that I was told one time were "sugar spots" and won't harm the plant but these almost look like something might be eating on your leaves. On the back of the leaves does it look like bite marks. If so, you may need to spray your plants with an insecticide or neem oil. If you do a search you can find some of the older threads regarding different insecticides. Also if the bottom leaves are the ones that are yellowing, that is normal for this time of the year. Some of my plants are starting to loose their leaves preparing to go dormant for the winter. Hope this helps. Joan

Jennifer —-(Spraying with Neem Oil and or and other mixtures to eradicate the insects organically could still harm those beneficial insects. Some people will just let those pest stay on the tree because they dont want to harm them. Its a difficlt choice to make for some and you need to understand that some bad infestations that might get out of hand and could cause your trees to become weak and allow other diseses to slowly kill your tree. i always try and let Mother Nature work on the right balance of the pest verses the beneficial insets to keep everything in check. But sometimes i will have to step in and use more than organic to combact the problem. its up to you to decide what is best for your tree. Laura Even those that eat leaves ___ Katydids 🌺

This is year 4 for my Plumerias. I have two that I have grown side by side from cuttings. This year I have one that is doing well with 3-4 inch healthy leaves. The other has not been able to sustain any leaf growth. The young leaf tips have been turning black and falling off. I do not believe it to be black tip, the growth tips are healthy and green. I did have one slip up about a month or so ago where they were both left out overnight at/just below freezing. I am in central North Carolina.