We have three elderberry bushes that have been growing beautifully in a sunny location. The bushes continue to look healthy however approx. two weeks ago I noticed the tip of a branch was drooped over. I thought perhaps my husband accidentally hit it with the top of the lawn mower (not the blade part) so I just snipped it off. Now, I am noticing more tips ( will vary from one to three inches long) that are drooping. What is potentially happening? We had an underground sprinkling system installed last summer, did something damage the root system although the bushes remained healthy throughout the summer and fall. The bushes are at the end of a small patio on which I did use ant poison which I have used every year since the bushes were planted, is that possibly causing it. All bushes have new growth on them. Help?? Thank You