HELP! I have 5 Oleanders about 2 years old and each about 6 ft high. They have been doing great, even got new flowers this week, but there's something wrong. The branches have always been very stout (stand straight up), but in the past 2/3 weeks the trees are all suddenly droopping and getting some yellow leaves and some leaves dropping off. Looks like Drought, but they get water several times a week, and there has been no change to their environment in the past weeks. Looked up Leaf Scourch, but has not invaded Florida, and it's the entire tree that's drooping, not just leaves. Could it be the sandy soil? If so why is it affecting them now after 2 years of fantastic growth? THANKS!!!!