Q.What’s wrong if my red bud has some yellow leaves?
Is my tree dying?
The good news is that most fungal diseases, including Cercospora, will not seriously damage the tree, but it will not look its best at times, including the loss of some leaves. The best way to manage this is to give the tree good cultural care, as stressed trees are more susceptible to problems. Eastern Redbuds, being originally from the Eastern U.S., need regular water and good drainage, so you should water when the top 2 inches of soil are dry, but not so much that the soil stays wet. A several inch layer of mulch out to several feet past the drip line of the tree will help, but make sure the soil close to the trunk is clear of mulch. Also using drip or soaker type irrigation near the drip line will help; to keep the leaves dry, you should not use overhead watering. If the foliage is thick you can lightly prune out the tree to improve air flow, and you can prune off and discard any dead wood and badly affected leaves to remove some of the fungal material. Clean up fallen leaves and debris under the tree as the fungus can survive in fallen leaves and twigs. You should avoid over fertilizing, as new growth is more susceptible to diseases. Anti-fungal sprays are not usually recommended in the home garden and are not usually helpful.
https://www.gardeningknowhow.com/ornamental/trees/redbud/caring-for-redbud-trees.htm
