They grow in Sacramento and you will see many of them here because they were selected for street plantings by the city about 15-20 years ago. They are now considered a problem tree. They produce small, thorny burrs that drop in the fall and winter. These trees are best planted out in open areas away from lawns and sidewalks. There are signs of borers on the cherry tree that I planted last year .
Prevention is the most effective method of managing borers.
Your tree may have been sunburned, which makes it vulnerable to attacks. Whitewashing the lower trunk with white latex paint can protect cherry trees from sunburn. Sound cultural practices should be employed sanitation, proper irrigation, and good pruning practices. Pruning is not essential, but Nandina domestica looks best if thinned annually. Remove old canes to the ground.