Good morning, and thank you for your question. The leaves may not be diseased, but responding to lack of water. Please read this information from another master gardener in response to question from another writer. 

By the way, from what I see, your photo shows unripened elderberries. Elderberry fruits normally mature between mid-August and mid-September and turn a dark purple when they are fully ripe. Elderberries right off the bush are usually tart.

I hope this information helps you maintain your shrub's health.
Jeanne

The existing root ball of a newly planted shrub dries out very rapidly because the roots haven’t yet extended into the surrounding soil. You may need to water the area of the original root ball every day or two for a week, then every other day for the following week, and so on. With time, you will be able to gradually extend the interval between irrigations. In order to know when to water, stick your finger into the surface of the rootball to determine if it is dry, moist or wet.

Another helpful tactic, especially during the first several months following planting, is to provide temporary shade to help protect your new shrubs against excessive water loss. Doing so will be important on days the temperatures soar, as they have done recently.

A tip for next time you plant, refill the planting hole with only native soil. No manure or other amendment. Further, don’t add any sort of fertilizer, including manure, until the shrubs are well-established, a year or two from now.