We would like to have more information. Please let us know how you care for the azaleas (watering, mulching);  where are they located (sun versus shade), have there been any changes to the site (construction, drainage problems, etc.)

Please send us photos of the whole shrub, around the base of the shrub, and affected branches so we can see what you are dealing with.  Possible reasons for branch dieback may be that the plant is in need of rejuvenation, possible canker diseases, etc. https://extension.umd.edu/resource/azaleas-and-rhododendrons-identify-and-manage-problems

Marian

Thank you. Attached are 3 photos of the Azalea in question. The plant is part of landscaping that has been in place for at least 20 years. It receives little sunlight and is watered via rain. There is minimal mulch. The ground is covered with English Ivy. The bushes are trimmed 3-4 times during the growing season. Haven’t noticed any canker issues.

Please advise if you have additional questions. Thank you…Clark Erlandson

We viewed your photos. Some reasons for branch dieback include weed competition, poor air circulation, and possible botrysphaeraia, a canker disease. 

If you have English ivy growing as a groundcover, we recommend removal. The ivy is competing with the azalea for moisture and nutrients. The azalea has shallow roots and the ivy will out compete for this.  Also, english ivy is invasive and we do not recommend planting it. It grows in many environments and it is also preventing good air circulation for the azaleas. https://extension.umd.edu/resource/english-ivy

At this point, we recommend that you prune out any dead branches now. You can prune the shrubs after they bloom.  We recommend thinning as the best option. Thinning and heading cuts, not shearing is the proper way to prune an overgrown shrub. This will  open up the plant to good air circulation and more sunlight. https://extension.umd.edu/resource/pruning-shrubs-and-hedges

The possible canker disease, Botryosphaeria canker can infect all ages of stem tissue through wounds, pruning cuts, and leaf scars. Heat, drought stress, and winter injury can increase disease incidence. Cankers on branches can gradually grow through the wood until the stem becomes girdled. You can look for this. 

Plants should be grown in partial shade, mulched, and kept well-watered during dry periods. The control is pruning back to healthy tissue. https://extension.umd.edu/resource/botryosphaeria-canker-shrubs

Marian