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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

9 comments:

  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

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  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?

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  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.

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  4. My young acacia (I water once every 5 days) has abundant growth from 1/2 way up each and every branch off the main trunk. BUT. . . each branch is loosing many leaves from the trunk 1/2 way out the branch -- then abundant growth. Why? Am I watering too much, too little?

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    1. Watering has two components, not one. One is watering frequency and the other is amount of water applied. Watering every five days means nothing to me. I can take a sip of water every hour and convince someone I am well hydrated. But another might ask...how big is the sip? One liter or one teaspoon? So when you water make sure enough water is applied to get it to at least 24 inches deep. How to know? Use 3/8 inch rebar three feet long. You should be able to push the rebar in the soil after irrigating, at least 24 inches deep. Wet soil allows the rebar to slip in easily. Dry soil it is hard to push. Unless you know it is getting enough water each time you apply it, you dont know if the tree is getting enough water each time. If this is not the problem then the problem could be in the trunk or limbs stopping water. Borers? Sunburn? But it sounds like it is a water problem.

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  5. Too bad I can't send you three pictures of the acacia. I water till I see the water come out of the very large vase in which the acacia lives. Is there a way I can send you the pictures for advice? Thanks.

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    1. You can send to me pictures at either of two email addresses. Phones SMS pictures will work IF I am in the US at the time. Sometimes I am not. Extremehort@aol.com or Xtremehorticulture@gmail.com You can embed them in the email or attach them to the email. Tell me the tree is located...Las Vegas, Mojave Desert, Phoenix, or country. I get lots of emails from all over.

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  6. My acacia shoe strings leaves dried with the Texas freeze. I removed the leaves the beginning of spring. Can I expect new growth? And when? It is April already 2021

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    1. Shoestring acacia is an Australian native tree that requires a surprising amount of water for a so-called desert tree. So be careful that it gets its 2 to 4 ft of water beneath its canopy every year. As far as it's cold tolerance, it seems to do fine to about the lower 20s. Below 20° and if there is wind on top of that you could lose branches to the cold. If there is late cold weather it can be more damaging than the same temperatures occurring in midwinter. I guess what I'm saying is the amount of damage can depend on its age. Older trees bounce back from cold weather better than younger trees. It's possible that if the cold temperatures last long enough and combined with wind and it's a young tree, the entire tree could be killed due to the cold. All you can do is wait and see. You will know by June, the beginning of Summer, if the tree is dead or alive and New growth if there is any will tell you a lot about whether you want to keep it, prune it back or ?????

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