Q. I planted a 24 inch boxed "Ped Push" Chinese pistache. After it was in the ground I removed the nursery planting stake. Now the trunk has a curve in it. Will properly re-staking help straighten the trunk?
A. The tree requires staking but not because the trunk is not straight. This will correct itself, on its own, over time. The tree requires continued staking for other reasons. Unfortunately, the production nursery that grew this tree did a bad job. The retail nursery that bought this tree got it at a good price. They are both at fault because they passed these problems on to you and they knew better!
Looking at the pictures it seems like you did a very good job planting. I like the idea of the berms around the planted area to hold water and help push that water deep enough to water the entire roots.
Remember that the berm should be about 4 inches high and the bottom of the burned area should be as flat as possible or all the water will build up on the low side resulting in roots that get plenty of water on the low side but not enough on the high side.
To compensate for uneven soil, the berm must actually be taller than 4 inches; taller on the low side and shorter on the high side.
I want to point out something to you about the tree and it will relate back to the staking. Look at the trunk of the tree. Notice that it does not have a lot of taper to the trunk. What I mean by taper, the trunk diameter does not change a lot along its entire length.
This is the primary reason it does not stand on its own very well and will require staking now. In a strong wind, because of the lack of taper to the trunk, it is very possible this tree could snap in two. If the trunk had taper, it is much less likely to snap in a strong wind. This has to do with a lot of engineering mumbo-jumbo.
The reason this tree does not have good trunk taper is because of how it was grown in the production nursery, not the retail nursery. But I will fault the retail nursery for buying these types of trees.
They know better but they got a good deal on it and they pass the savings on to you, hopefully, and you probably bought it because it was inexpensive compared to others and you didn't know any different.
Trees with a lack of taper on the trunk are grown too close together in the field, they are pruned incorrectly to encourage height at the expense of a lack of taper. Then they stake the trees because they cannot support their own canopy weight because of a lack of taper and this problem is passed on to you. And I challenge these nurseries to prove me wrong! I know I'm right and it makes me mad to see these kinds of production practices all because they want to make a buck.
What can you do to correct this problem? You're going to have to stake this tree or it will snap in a strong wind. Guaranteed.
Where to stake it is important. The bending and flexing of the trunk is important in the development of taper. If the tree is staked so the trunk cannot move back and forth, e.g. flexing and bending, this will contribute further to this problem.
Secure the trunk to stakes so that the bottom of the trunk does not move. You do not want the bottom of the trunk going into the ground to move. You want the top of the tree to flex back and forth, but not the bottom.
The trunk should be secured high enough so that it does not snap but the top of the tree can still move. This would be roughly about halfway up the trunk.
Secondly, if any shoots grow from the trunk, do not prune them off!! Let them grow until they get about pencil diameter and then prune them off from the trunk leaving no stubs behind.
New shoots should always be allowed to grow from the trunk because they help contribute to trunk taper. But remove them when they get older, always allowing the young ones to remain. Once the tree no longer requires staking, then keep the trunk clean of any new growth and remove it as soon as it appears.
If you by any large trees, 15 gallon and above, in the future I hope you will consider trunk taper or the growth of side shoots along the trunk when purchasing a tree avoid nurseries that sell inferior plant quality.