I have two blooming plum trees that were planted the same time ( 4/14). They were both doing good 15,16 , but mid way through the summer of 17 one of the trees started to lose it leaves. This spring one of the trees bloomed beautiful,where as the second one (the one that lost its leaves early) started blooming later with very thin leaf growth. They are about 30’ apart.
This can have many causes. Can you include a photo, so that I can see what is going on? This will help me to make a better judgment call.
the leaves are small and not filling out
I suspect water deficit and/or nutrient deficiency.
Soil fertility and water management are vital for plant health, foliage and flowering.
Water a wide area not just near the tree trunk, but the entire area of the absorbing root zone which spreads as far as the foliar canopy and more.
Water deeply to wet the soil a minimum of six inches, preferably to 10 - 12 inches. Check this two to four hours after watering, or the next day, by digging down in a couple of spots to see how far the water infiltrated.
Mulch the soil surface to help retain soil moisture.
Fertilize spring and summer with a slow release complete organic fertilizer.
It might be poorly rooted and trying to get some leaf growth to gather enough energy to root. Make sure that the soil is not too moist or too dry, as this will inhibit rooting.
Make sure to let the soil dry out down to about 3 or 4 inches between watering, or even more! Not enough water is much better than too much water.
Unfortunately, your images did not come through so I am unable to see the state of the soil. If it is too compact, you may need to loosen it up. Earthworms can do this without disturbing your roots.
Here are some articles that will help:
https://www.gardeningknowhow.com/edible/fruits/plum/purple-leaf-plum-care.htm
https://www.gardeningknowhow.com/composting/vermicomposting/creating-worm-beds-in-gardens.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-attract-earthworms.htm
https://www.gardeningknowhow.com/composting/vermicomposting/benefits-of-garden-worms.htm
The tree bloomed in spring with flowers and then leaves came on later. The side of the tree that leaves are drying up are facing the North where we have had intense heat from the sun. The side facing the house looks great. Not sure what to do!
This could, very well, be heat or sun stress. If you suspect this, then there is nothing to be done outside of providing shade or relief from heat during this time.
However, there could be a number of reasons outside of this which may require the assistance of your local extension service. Root girdling and disease can be an issue, as well.
https://www.gardeningknowhow.com/extension-search
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-is-dead-on-one-side.htm