Q. A nursery planted my tree in spring (May I think) it has sap running in several places from the trunk. Also the leaves seem to have some disease, but the new leaves at the base of the trunk look great. I have looked on the internet but could find an answer. It looks like it's dying. What is your prognoses - see attached photos taken today.
|Trunk of this Chinese Pistache|
A. I looked at the pictures of the pistache tree that you sent to me. The pictures make me think it is water related. Your Chinese pistache is probably a grafted tree. A graft is used to attach two plants together; one which will become the roots and the other becomes the trunk and top of the tree. If you look at the trunk of the tree a few inches above the soil you should see a slight "crook" or bend in an otherwise straight trunk. This bend is where the graft took place which joined the two young trees together.
|Picture of leaf sent in|
This is important to find. If the new leaves you mentioned at the base of the trunk are coming from below this crook or bend then the tree is "suckering" from the plant grafted for the roots. This is a very good indication that the top part of the tree has been damaged or is under a lot of stress. Normally, this is not a good sign and you don't want this type of growth to continue. You would remove this growth from the trunk and is close to the trunk as possible. If you leave any short stubs after you remove these suckers then growth from this area is likely to return.
What caused this? This is where I go out on a limb, no pun intended. Nine times out of 10 this is related to some sort of watering issue. I am going to guess and say it's not getting enough water. If this was a 24 inch boxed tree you should be delivering about 15 to 20 gallons of water each time you water. I am guessing this tree is on drip irrigation. I can't tell you how many minutes this would be because that will depend on how much water these emitters are delivering. A tree of this size should have a minimum of four drip emitters spaced in a square pattern about 18 inches from the trunk. If I am correct, you should be able to correct this problem by building a basin or bowl around the trunk about 3 feet in diameter and 6 to 8 inches tall. You would use a hose and fill this basin with water completely once a month during the winter months. When things begin to warm up in about March you might do this every two weeks. Once you hit may you should be doing it weekly.
Another possibility could be that it is receiving too much water. If you are watering daily and delivering a lot of water through those drip emitters than it is possible the roots are suffocating because of too much water. I tend to believe it's not enough judging from how the tree reacted.
What to do? Build that basin around the tree that I mentioned earlier. Fill this basin with water from a hose twice. Remove the suckers from the tree as I described. If you think there are not enough emitters, add emitters around the tree or find some way to deliver a higher volume of water if you are only watering a few minutes. You won't see much of a reaction from this tree to these improvements until next spring and summer. Remember, do not water daily. When you do water, give it a lot of water and wait a few days between irrigations during the summer months.