Q.Burning bush
Every August my burning bushes lose their leaves. In a two week period the leaves look sickly and fall. Every spring the plants bud out new growth and leaves, they look very healthy. The branches look ok, no bugs. The plants are 4′ tall, at least ten years old and are on each end of my home about 40 feet apart. Any suggestions.
Locate the burning bush in well-draining soil, because it does not like soil that stays wet for long periods. Depending on the rain and fog level of the area, water the plant only when a dry spell occurs. Pour the water on the ground around the bush. Watering with a sprinkler doesn't soak the ground well enough. Let the ground dry out between watering. Normally the burning bush needs water once a week during the summer.
Mulching benefits the burning bush by keeping the roots cool and conserving water. Spread about an inch of organic mulch around the root zone. Organic mulch includes shredded newspaper, sawdust, dried grass clippings and dead leaves. These materials break down over time and slowly add natural nutrients to the soil.
Spider Mites and Scale are common on a Burning Bush and can cause leaf drop if the infestation is not kept in control.
https://www.gardeningknowhow.com/ornamental/shrubs/burning-bush/burning-bush-care.htm