Golden canker, is a common disease that affects pagoda dogwood. This disease will discolor and kill branches and can progress from branch tips into larger main branches and stems. Once the disease reaches the main stem, the stem will quickly die, but the root system will survive.
Cankers are present year-round but are easiest to see when trees are dormant. The bark on infected branches turns a bright yellow or tan in contrast with the normal, healthy purplish-green bark. Multiple small, orange, raised bumps develop on the surface of infected bark. The cankers are generally found at the tips of branches but can spread down the stem to affect more of the plant. Infected branches may not leaf out, as you are observing in your shrub. During summer, the disease can also progress and manifest with infected branches showing wilting leaves that eventually die and remain attached.
The best way to control this disease is to prune off infected branches by making a cut directly above a healthy bud or branch that is at least two buds — or 2 to 4 inches — below the yellow, discolored bark. Prune just above a bud or branch, being careful not to damage it in the process of pruning. Try to avoid pruning the branch back to the main stem if possible.
It is better to do this pruning when the trees are dormant, with temperatures somewhat consistently below freezing. This will help reduce the number of spores produced within the canopy during the growing season. But go ahead and prune out the infected branches now. You may be able to get a few more years out of the plant; decide whether to remove or save the dogwood based on how it looks after you have removed the dead branches.
It is important to sterilize your pruning tools between cuts to avoid spreading the disease. I like to use Lysol disinfectant in a spray can for this purpose. After removing, either burn the infected branches or otherwise remove them from your garden.
In addition to pruning out infected branches, it is a good idea to lightly fertilize and mulch your dogwood and provide supplemental water during any extended dry periods that occur during the growing season. Providing extra maintenance will improve the vigor of your plant.