Question
I have had this gardenia bush for over 15 years. It started last year getting growths on the trunks, they look like nests that can be brushed off. They don't come off completely.Their dark brown. The branches have been dying and leaves are getting yellow. I've looked up information, but I'm not sure if it could be a nematodes and if so what can I do to save the tree.

Answer
Dear Nancy, This story reminds me of one of the worst things that happened to me as a gardener.  I had 5 gorgeous gardenias in front of my house and they got similar symptoms to your bush.  I was pregnant and couldn't spray and ended up losing them all.  So anyway, I am certain of what you need to do for your plant.  It is never a good sign when gardenias have dieback on the branches as they are one of those plants that really never need pruning.  You very likely have some type of beetle or scale that is causing this problem.  I was able to tell mine had a small (1/16") beetle by putting some affected branch in a baggie for a few hours and the beetles would start to drop off.  If it doesn't do that it is probably scale, but either way I would probably use a mixture of dormant oil (horticultural oil) and the strongest insecticide I could find.  They have taken so many things off the market lately, and I'm not sure what will be available in your area, but you can go to a feed store, garden center, or Home Depot or Lowe's and get the strongest available product.  If the label says you can kill Japanese beetles with it, that would be a good one to use as they are generally tenacious.  Mix the appropriate amounts of oil and insecticide in a sprayer (you can get a cheap pump up sprayer) and spray the heck out of the bush, trunk, top and bottom leaves, soil around it, everything.  Repeat every week until the dieback ceases and you will save the gardenia.  Be sure to do it right away, and let me know if you have any questions.  Good luck, Melissa