dying trees

Asked May 13, 2020, 11:33 AM EDT

My trees have been having trouble for a few years now. First, dogwoods were not producing leaves near the tops and the bottom leaves were very small. An arborist said they needed a root treatment. The following year two of them did better, and one died. This year the pinoak and redbud are showing the same problem with very small and sparse leaves. I know the drought last year may have affected them, but they've never shown drought problems before. I'm wondering if there is a problem with the soil. Most of these trees are between 35 and 40 years old. The oak may be a bit older. Can you give any advice?

Howard County Maryland

1 Response

We can't see any disease or insect issues from the photo. The leaves don't seem to be fully expanded yet. Photos of the base of the tree and the general layout of the land would be helpful. We can't give you a specific answer. The problem may be abiotic--meaning environmental or weather.

A managed landscape is not a natural environment. Mowers and foot traffic compact soil. The usual leaves and twigs that would fall, decompose and feed the tree if it were in a forest are not allowed to do that. We interfere with natural cycles in other ways, too.

We have had tough weather conditions for a few years. Abnormal rainfall for a year and a half, followed by a severe drought last summer and fall.

For your particular trees, here are some thoughts:
Dogwoods: Dieback starting from the top suggests root issues (can't get water and nutrients up to top of tree.) Roots can drown if they sit in saturated soil too long, or dry up if soil is not absorbing water. (Are these trees on slopes where rainfall runs off? That means dry soils.)

Redbuds are short-lived trees. They may be at the end of their life times. (Dogwoods live longer, but 35-40 years is getting pretty old for them.)

Pin oaks like moist soil. The bigger the tree, the more moisture it will need.

All of these trees prefer acid soil. Lime on lawns is going to raise pH and make your soil less acid.

Old soil gets compacted. Then neither oxygen (critical for roots) or rain can get down to roots. You could try using a core aerator over the lawn and then top dressing with a composted organic soil amendment that will fill in the plug holes to get oxygen and rain down to roots better.