We have had these bottlebrush bushes in our backyard for about ten years. This past year they look like they are slowly dying. They have been watered the same way for the past ten years through our water sprinkling system. A week ago my husband put fertilizer on them but it hasn't done too much. I was thinking maybe we need to prune the dead away but I don't know if that would help. Any suggestions what is wrong with this bush?
Your picture is small and not very clear but I tend to agree with Judy as it does appear you have webbing and that could be spider mites.
The best way to see if this is the problem is to simply shake some of the foliage over a plain sheet of white paper - if you see tiny specks moving around on the paper then it's probably spider mites.
Even if it is not spider mites your best solution is to spray your plant with either Neem Oil or Insecticidal soap - follow instructions on the container. This solution clings to the foliage and kills the insects. It is usually considered safe for all plants as it is non-chemical but follow instructions.
These products can be found at any of the big box stores or online.
You will probably need to cut your plants back severely to get rid of the insects and the deadwood but I would suggest you contact You County Extension office and ask for advice.
Send them pictures and size/age of your trees.
They will know more about what is happening in your area and can provide all of the information you need to save your plants/trees.
You have spider mites. Get a spray for that at the garden center.
This website describes issues that may arise with Bottlebrush and how to manage them. Inadequate drainage might be at fault if the soil has compacted over the years. Good luck! havegarden.com/
I could not see the spider webbing in this poor quality photo. If you can see it in the photo, then it should be very noticeable and I doubt that the owners of this bush did not notice it. I dont think people put fertilizer , wondering whats wrong with the bush, and dont notice such a large webbing. Most likely the owners of this bush asked the question: what is it on our bush?
I see that the bush has turned yellow. This happens due to Iron Chlorosis. Leaves become yellow and dried. This is followed by the death of the branches and stems. Iron Chlorosis happens in two situations, improper watering and compacted soil.