This phenomenon can be very common on Burning Bush and tends to be caused by either drought stress or a heavy outbreak of spider mites (or the two overlapping). We can't see enough detail of the leaf symptoms from this distance to narrow it down further, so if you can share close-up photos, that may help. Other conditions are possible, like a secondary fungal infection like Botryosphaeria killing branches that were originally stressed by drought or some other environmental condition, but that would not be the sole issue for this extent of damage.

Short of making sure the shrub is monitored for watering needs during this ongoing drought, there is nothing you can do. There is no treatment that will reverse existing damage, and no pesticide can be sprayed while temperatures are above 85 degrees without causing even more plant tissue damage. (Plus, even during a cool-down, treatment is not practical since the damage is already done.) You can blast the undersides of the still-green foliage with plain water from a garden hose (make sure you run out the hot water first) to dislodge some mites to at least give the plant some temporary relief.

Burning Bush is an invasive species that we encourage gardeners to replace. (Its sale is also regulated by the Maryland Department of Agriculture, where nurseries are permitted to sell it only if they warn consumers of the plant's invasive traits. Pending changes from recent legislation, though, might ban the sale of this and other invasive plants entirely, depending on how the new law takes shape.) If you find that this shrub is succumbing to damage too often, consider removing it and installing a different species. Heavy pruning and shearing, which forces foliage into a denser layer on the outside of the branches, exacerbates leaf shedding and the risk of pest or disease outbreaks for many shrub species, because it reduces airflow around the leaves and reduces light reaching into the shrub's center.

Miri

Thank you for the additional pictures. The symptoms pictured confirm a very heavy spider mite population (or very heavy damage, at least) coupled with drought stress. Yes, do water the root zone to keep the roots hydrated; the water spray advice regarding the leaves was in to remove some mites in lieu of being able to use a pesticide. Mites tend to inhabit the underside of plant leaves, though occasionally they can be found on both surfaces. The force of strong water pressure in a harsh spray (not enough to knock more leaves off, but not a gentle mist either) will dislodge enough mites to hopefully reduce the feeding damage a little bit, at least on leaves not yet heavily affected. (It won't accomplish much to bother spraying the leaves already very tan/brown/bleached-looking. Leaves cannot heal from damage.)

Miri

Yes, the leaves will be a clean slate next spring. Removing the fallen leaves this year might help to reduce any mite persistence in the meantime, though, or at least help irrigation efforts better reach the root zone below.

There are likely plenty of alternatives if you replace the shrubs. Narrowing down the list of candidates will depend on factors like site conditions and preferred aesthetics. With a bit more information we're happy to provide some ideas. For example:

• How much sun does that area receive? ("Full sun" is 6-8 or more hours of direct light in summer.)
• Does the soil drain well? (Probably, given the utility box.) Does it tend to be dry, even when we're not in a pronounced drought? Are there nearby tree roots growing into that area that will be competing with those plants for water?
• Do deer visit that part of the yard and browse?
• What mature height (without relying on pruning) would be ideal?

Miri