Why Is the Bark Splitting on My Bottlebrush?

Q. Do you what is causing the bark and stems of my bottlebrush bush to split and die on the East side?  Here are a few pictures.  I don’t see any pests.  Overall, the bush is healthy (except for a few of the branches which have bark that is splitting) and it has a lot of new growth and leaves.  Only the older branches are splitting in some spots and then entire the branch dies (top to bottom). I would estimate that only about 20% of branches/limbs have bark which is splitting. The bush was planted about 4 years ago and was purchased in a 5 gallon container. I haven’t changed the water frequency or the fertilization schedule.

A. From your pictures the splitting does appear to be on the side most open and in this case the East side. To get sunburn it doesn't take that long of intense sunlight, maybe 20 or 30 minutes.

If this damage extends more than halfway around the upright stems then I would consider cutting them back. You would cut them back to remove this highly damaged area. These cuts might be quite deep inside the canopy.

That's okay because the shrub will come back and it will come back quickly to the size before. The roots will be large enough to push a lot of new growth back to its original size, then it's growth will slow down again. I would make these cuts probably around late January or February 2015.

Make sure you have enough drip emitters to provide the water that's needed. This plant does not like to be watered daily, so avoid that.

These plants tend to get yellow or iron chlorosis so I would supply either a soil application of a good iron chelate such as EDDHA or 138 iron chelate.

You can do the same thing with multiple sprays of a less expensive iron product what it might take several sprays to get much greening out of the sprays.

Fertilize after you prune this rub with an all-purpose tree and shrub fertilizer. One application a year is enough.