For new landscapes people tend to generally plant the new 'purple leaf plum' trees in a square shaped small plots. They also plant some small plants around it to make it look good. However when the tree grows older it needs to spread its roots. At that time these plants may try to hinder the trees roots growth. Therefore it is advisable remove them once the tree starts growing bigger. Then you can also add water to the roots by spreading it around the area of the tree.Whenever there is problem of heat and high temperatures, then the leaves get burnt and fall off. However when the cooler season starts they again grow normally. You may have to cut off any dead wood from the branch due to sun-burn. You need to maintain the plant by frequent pruning and maintenance. Another problem is of the leaves getting brown in color. You can check this problem by over-watering the tree. You also need to check and remove any growth of mushrooms on the trunk base. You have to remember that whenever the summer season is gone the tree shall start growing again in cooler temperature.