Sunburst Locust are dying

Asked September 4, 2019, 11:58 AM EDT

I have a green to blue-green growth on quite a few of my trees. They are Sunburst Locust, fruitless ornamental pear & spruce trees. Is this a fungus? Is it what's killing them? I don't see any actual bugs or anything on any of them. The locust hasn't had very much new growth this year either. Any help would be greatly appreciated.

Genesee County Michigan

1 Response


Honeylocust this year seems to have not done well, we have had several questions about it. I suspect the winter’s polar vortex, and cool wet spring followed by a warm, relatively dry period has stressed the trees.

The picture of the leaves looks like honeylocust plant bug damage.

The lichen are a symbiotic combination of algae and fungi that take no resources from the trees or shrubs. They do not hurt trees or any other plants. They are just using the bark as a perch, as they do on dead wood, rocks, and even cement. There is no need to remove them. They do grow better on dying, sparse, slow growing branches because they receive more sunlight there; and because the slow growing or dead bark doesn’t expand and essentially “push” them off. Here are details on lichen:

What you can do-

Give your trees and shrubs 1 inch of water per week around the root zone during dry weather from spring to late October, up to when the ground freezes.

It is best to remove plants or turf in a wide circle around the tree and mulch this area.

Mulch no deeper than 3 inches with organic mulch, keeping it pulled back from the trunk 2-3 inches. Hand weed this area, so as not to cut, nick or otherwise damage he bark. Do not pile mulch against trees or shrubs. This link explains in detail - he care and mulching applies to established trees and shrubs, too-

Fertilize in spring according to a soil test result.

Follow the honeylocust plantbug recommendations( link above) next spring.

The root zone may be compacted. A certified arborist can correctly aerate the root zone, excavate the root collar if needed, to improve tree health.

Hire a certified arborist, a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan. Find certified arborists by zip code here—-

Pears and spruce will have different pests and issues. However, they all need about the same amount of water per week when we have droughts. The mulching techniques are the same, and soil compaction will affect them similarly, too. The arborist can diagnose them all on the same visit.Thanks for using our service.