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Tuesday, July 10, 2012

Shoestring Acacia Losing Lots of Leaves

Freeze damage to shoestring acacia
Q. I had three shoestring acacia trees planted 5 years ago and right now they are losing a tremendous amount of leaves. They are on high flow emitters that are adjustable and putting out a large amount of water. They get watered every other day for 15 minutes. The trees are approximately 20 feet tall.
            Is there any reason why they would lose so many leaves?  My understanding with these trees is they produce very little litter but that is not the case. I would appreciate any help you could give me on this. Also there are 4 emitters for each tree about eight to ten feet from the trunk.

A. Shoestring Acacias (Acacia stenophylla) has a long record of success in desert regions of the west.  This good history of success is often the result its adaptability and letting the soil dry between waterings. 
Flowers of shoestring acacia
            Your comment that the 'leaves' are falling (Oddity fact: The long thin 'leaves' are in fact phyllodes and not true leaves but do the photosynthesis) leads me to think the very frequent watering has set up conditions not conducive for a maturing tree.

            After 5 years in the ground I would think your watering cycle could be as much an issue as anything.  Unless you live on some of the very sandy, stable dune soils of Palm Springs or in southern California/southwestern Arizona (Yuma mesa area) trees in the ground for 5 years would be better watered much less frequently with a larger volume at each watering.  This would also include having the source of the water being moved out away from the trunk targeting the water out closer to the drip line of the tree. 

            Whether there might be a disease involved and complicating the situation is nearly secondary.  The watering regime you described could easily have set up the conditions for the fungus to get started and any treatment would include a change in watering schedule to allow drying between waterings.
            Please feel free to respond if you have any questions or other things that might have 'hit' the tree. Things like: root damage from digging, severe wind that may have damaged the trunk, certain herbicide (weed killer) usage, pool back flushing, inadvertent chemicals spilled in the area, compaction from parking vehicles in the tree's shade, etc. 

            I would be interested if you live in a marginal cold area.  This tree begins to suffer if the temperatures drop to the high 'teens.
Terry Mikel


  1. We have a shoestring acacia in Tucson Az, and it sheds so much its annoying the HOA. Can you help? Please email at desertdry4@aol.com. The tree is on an irrigation system. Thank you

  2. I also have similiar problems with a 10 year old approximate 40 foot shoestring acacia. It does seem to respond to infrequent deep watering. Unfortunately it has grown to reach over my pool and my neighbors yard. In addition the pea or seed pods are really a mess both on the ground and in the pool over what I consider an extended spring duration. I believe it should nearly be against the law to cut down a healthy tree in the desert but I am considering romoveing this tree if I can't get some relief. I'm considering a trimming that is way beyond normal as a first attempt to live with this tree. I'm thinking of topping (I know that is not generallly accetable) taking as much as 15 feet off the top. Due to the basic shape of this tree, that would not help on the crown diamiter. I'm seeking any suggestions before I do anything in hopes that I can avoid the removal.
    This tree is in Phx AZ so has no cold to speak of but may have experienced a little unusual heat this past summer. Since my infrequent and deep watering is manual, I may not have the right schedule. Can you suggest what that is?

  3. I would welcome other comments but you can look at most trees that come from desert regions of the world and see if they are being under or over watered. If under watered, the tree canopy will be sparse and not full. A reaction to minimal water for many desert plants is to drop foliage because water is not available. It tries to shift its water use to the water use available. More leaves = more water use. If watered in excess many (not all) will show alot of rampant new growth. A deep watering once a week in the summer is probably adequate. If not, water more often. Decrease the how often you water (not the amount at each watering) in the spring, fall and winter months.