I have been a member for several years but just don't post and now I have a question about a few oleanders I have. They have had scale in the past but I think for the most part is that under control with horticultural oil. I use the Bonide brand. I know they don't get enough sun where they are but I am not going to move them as they have gotten too big. They do get sprinkled with my irrigation system every day in the warm months.
Although they have many healthy leaves too many of them get these brown spots on them then they turn yellow and die. I used to think it was scale damage but now I am not sure. The plants are thriving otherwise and a few are over six feet tall. Any help would be appreciated.
I agree with Elaine about the watering. When I grew up my parents had a very long Oleander hedge on the front of their property. It was irrigated every 2 weeks during the Arizona summers, and they grew and bloomed very well. They were never fed with anything, and lasted years until the city widened the road and they were destroyed.
The last picture is of the underside of one leaf. There is a small white spot that I think was scale but that is about it on most leafs. Before I started with the Bonide it was much, much worse.
The oleanders are just on the periphery of my sprinkler and they get very little water each day. I pretty much live on an island that has sand for soil. Very poor quality. Water goes right through it. But it could be too much water on the leaves every day but they dry off quickly with our heat. There is a salt water marsh at the rear of my property that is less than 50 yards away. Water never gets up this far even with high tide though.
There is no salt spray but the air is definitely salty. Anything made of metal and left outside will rust. The marsh is for the most part dry until we get a very high tide. Alligator territory. It is what this part of Georgia is known for on the coast. Called the Golden Isles for the grass in the marsh. Many oleanders are grown around here.
I still tend to think it has to do with scale damage but I will adjust the sprinklers to keep water off the leaves and plants. I wish they had more sun but there is nothing I can do about that.