If the plant perks up after watering, try to water it everyday or transplant it into a slightly larger container. What can I do to save this tree. Ron, Crabapples are taking a beating this season. The past two spring have been cool and wet. This is perfect for diseases and tough on crabapples.
Apple scab causes black spots on the leaves.
The leaves often yellow and drop. I saw several defoliated crabapples in late June this year. Rake and destroy fallen leaves. Fungicides can be applied next year to reduce the disease. Apply 4-5 times at 10 day intervals starting at budbreak.