Hi Evie,

Based on your pictures, I believe your burning bush has lichen growing on the bark. Lichens are a symbiotic combination of a fungus with an algae or bacterium. They can be found on any non-moving substrate like rocks or woody plants. Lichens are commonly found on the bark of tree and shrubs in Michigan. In some cases, trunks and branches may be completely covered by lichens. This colorful lichen does no harm to the plants. Lichens are completely self-supporting organisms. The algal component provides sugars through photosynthesis, and the fungal component obtains water and minerals from the air, water or surrounding environment. Neither organism is parasitic to the bush. Colors of lichens vary widely and include white, gray, red, green, yellow and black.

No management is necessary or should be done to reduce the presence of lichens on a tree or shrub. In fact, finding lichens on a tree or shrub in your yard is a sign that the air surrounding the tree or shrub must be pure since lichens will not grow in areas with a smoky or polluted environment.

However, lichen growth can indicate that the bush has been stressed. The bark of a healthy tree continues to expand and slough off with the growth of the tree. The bark of an older or stressed tree may become more brittle with more cracks and uneven surfaces permitting lichens to attach themselves more readily. You mention that your burning bush doesn’t have as many leaves as it used to so that is the problem you need to address. I can’t tell what the problem is from your pictures but it may need fertilizer, or some pruning, or it could be a water issue (too much or too little). Burning bush are also susceptible to oyster shell scale.

Thinning leaves on a burning bush can be a sign of stress or disease. Here are some potential causes and solutions:

Cold weather can cause the burning bush plant to lose leaves. Experiencing a late spring frost, when the bush is just starting to leave out, is one possibility. Two-spotted spider mites can infest burning bushes and cause leaf drop and browning. Spray the shrubs with water to wash away mites and use horticultural oils or miticides like malathion. To determine if this is the problem, take a plain white sheet of paper and hold it under one of the branches and tap or shake the branch. If you see tiny spots that move around on your paper, it could be mites. Diseases like powdery mildew can also lead to leaf drop. Powdery mildew is white and forms on the upper side of leaves. Your leaves look like they could be a little gray but when I zoom in on your pictures, it gets too blurry. The solution is to get more air circulation, so pruning out a few of the older branches may help. You can also use a fungicide earlier in the growing season. Spraying a fungicide at this time of year will not do any good. Clean up and dispose of any fallen leaves. I’ve included a link to some of these possible problems at the end of this message. If you want to know for certain you can send in a sample to the Pest ID lab on Michigan State University’s campus. Here is the information for that. Plant & Pest Diagnostics There is a small fee for this service. If you’d like to have a soil test done you can purchase a soil test kit here. Home | MSU Soil Test After you send in your soil sample, MSU will send you an analysis and include suggestions on what soil nutrients you need to add.

What powdery mildew looks like: BP-5-W.pdf

Spider mite damage: Burning Bush Spider Mites.pdf

Here are some of the references I used:

Lichen, Algae, and Moss on Trees | University of Maryland Extension

FS1205: Tree-Dwelling Lichens (Rutgers NJAES)

Hope this helps.