Q.Why Is My 16 Year Old Pistachio Not Leafing Out Properly?
The tree was lush and green up till last year. The tree looks healthy and what leaves that are on the tree are green. I do not see any bugs, wilting, yellow or curling leaves. There are small buds throughout the tree that appear to be green (there appeared to be a very small amount of brown toward the middle. There are some smaller dead branches. I water the tree 20 minutes minimum (sometimes I forget and let it run longer) 2X a week. I put a 5-5-5 all purpose fertilizer around the trunk about a month ago and 3 TBS of B1 in 2 gallons of water around the drip line today (at the suggestion of a local nursery.) Today, I did notice what appears to be a 12+ inch shallow vertical slit on two branches and here is a kind of rust on some branches. I was told the rust was normal on older trees. The tree branches are starting to butt up against my neighbors Crape Myrtle but, I trim back the branches on his tree.
Certified GKH Gardening Expert
Unfortunately, this is going to be an issue of climate. In order for your tree to be healthy, it must be very hot in the summer (100+) and in the winter it must fall below 45 degrees. It is, also, necessary to provide, almost, drought like conditions to the tree. They will not tolerate frequent watering, very well. In fact, I would run what you run maybe once every 2 weeks, or so. Just don't feed it often, since they won't be very heavy feeders.
This article will help you to know more about the requirements: