Answer: Poor George! That is a terrific sized specimen at 8 feet! I think what you have is a Euphorbia trigona (sometimes listed as E. trigonum). I suspect the damage may be cold injury, possibly also some physical damage. If there is cold damage, it may continue to die back somewhat until it reaches completely healthy tissue. It is better to remove anything that is damaged to reduce the risk of disease attacking the damaged portion. This plant should regrow relatively quickly due to the established root system. I think allowing it to acclimate to the new location and recover on its own time is probably the best approach. The white spot might be sunburn if it is suddenly in more direct sun than previously, or it might be a fungal infection. Try to set it in the same amount of light and in the same orientation as it grew before to minimize the shock of being moved. Also make sure there is good air circulation around it to minimize the chance of infection attacking the damaged portion and do not keep it in a humid area. Ordinary indoor household air is quite dry in the winter due to our heating systems, you would not need to add humidity for this plant. I hope George is doing better soon.
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