Deep root fertilization for Ailanthus altissima - Ask Extension
My 30+ year-old Ailanthus has been ailing from drought the last 2 summers. I've lived here 21 years, & it used to be lush
& thick w/ a wide ca...
Knowledgebase
Deep root fertilization for Ailanthus altissima #121607
Asked April 14, 2013, 5:27 PM EDT
My 30+ year-old Ailanthus has been ailing from drought the last 2 summers. I've lived here 21 years, & it used to be lush
& thick w/ a wide canopy--2 stories high. It has had a few dead limbs here & there during this time, but, as I say, it's really been suffering
lately. It's in my back yard where I water & fertilize my grass, but I
know that's not enough. 1-1/2 yrs ago I had professionals prune it & cut off dead limbs--yet last spring there were additional dead limbs. It has about 1/2 the
canopy it had 21 years ago. The professionals said it could benefit from deep
root fertilization. I'm researching how to do it myself: Yard Butler
Deep Root Irrigator vs. Ross Heavy Duty Tree & Shrub Root Feeder,
etc. (I see that it can suffer from verticillium wilt, but I haven't been inspecting its leaves & the tree isn't yet leafed to inspect now.) I can figure out most of it, but I've had no success online or at a
well-respected local gardening emporium in determining the optimal fertilizer. Could you kindly make a recommendation as to
fertilizer, &, if you have other suggestions for my project, I'd
appreciate it as well. Many thanks.
Denver County Colorado
Expert Response
There may be many reasons why your Ailanthus tree is experiencing die-back. If 50% of the canopy is dead, the prognosis does not look good. Fertilizer is not a cure-all. That being said, any fertilizer application should be based on a soil test. Soil can be tested via CSU at: http://www.soiltestinglab.colostate.edu/documents/soilsample_horticulture.pdf
Proper watering and mulching and pruning out deadwood is always recommended. Feel free to check out our fact sheets for more information:
http://www.ext.colostate.edu/pubs/pubs.html
Hi, Alexis,
I feared as much. Thank you for your suggestions. I am filling out the soil test form right now. I am grateful to be on the right track rather than paying $ to the tree company for possibly useless or harmful deep-root fertilization for my Ailanthus, or spending $ to do it myself. ~Best, Jane W.
I feared as much. Thank you for your suggestions. I am filling out the soil test form right now. I am grateful to be on the right track rather than paying $ to the tree company for possibly useless or harmful deep-root fertilization for my Ailanthus, or spending $ to do it myself. ~Best, Jane W.
Hi, Alexis,
How do I obtain the container specified in the soil test instructions: "Place the soil sample into the CSU soil container (preferred)"?
Thanks,
Jane W.
How do I obtain the container specified in the soil test instructions: "Place the soil sample into the CSU soil container (preferred)"?
Thanks,
Jane W.
We used to have self-addressed containers, but not any more. A plastic bag filled with soil placed in any mailing box will do.
Thanks, Alexis -- I've got the composite soil bagged and ready to box and ship. Could you please elaborate on the most likely causes of the die-back?
Thanks,
Jane W.
Thanks,
Jane W.
Verticillum wilt and ambrosia beetles have been known to affect Ailanthus. Many other causes could be root damage or recent construction, drought, and old age.
Thank you, Alexis. ~Jane W.
Alexis, how long does it take to receive sample test results? My USPS tracking shows, "Your item was delivered at 8:05 am on May 1, 2013 in FORT COLLINS, CO 80523." It's been over two weeks since my soil sample was received... ~Thanks, Jane W.
On average it takes 2 weeks, but this is their busy season. I too am waiting for a soil sample from late April!
Hi, Alexis,
Thanks for letting me know the time frame. I received the report by email two days ago.
Here's the status: 1. I sent a topsoil composite from 9 samples beneath the drip line of the Ailanthus. 2. Organic Material and Nitrate (18 ppm) are low, other readings are High, Medium, or Adequate. The only suggestions offered are for the Organic Material and Nitrate. For all other readings, including High, it just says "No additional _________ is needed." The texture estimate is Sandy Loam, which can dry out. Three sample areas never receive human watering (they can't because of location), which adds to dryness. 3. I don't know how these results should guide what I do for my Ailanthus -- can you advise? 4. There is one significant limb death since last year -- part of it was on its way out by last fall, and now the entire limb is gone. 5. As a late leafer, the leaves are just beginning to unfold, so I can't yet check for signs of verticillium wilt. Should I wait until the tree leafs out before I try something like deep-root fertilization? 6. She's still a good tree, even if she's on borrowed time, so I'd like to try something. I can afford to fertilize her roots myself.
Thank you,
Jane W.
Thanks for letting me know the time frame. I received the report by email two days ago.
Here's the status: 1. I sent a topsoil composite from 9 samples beneath the drip line of the Ailanthus. 2. Organic Material and Nitrate (18 ppm) are low, other readings are High, Medium, or Adequate. The only suggestions offered are for the Organic Material and Nitrate. For all other readings, including High, it just says "No additional _________ is needed." The texture estimate is Sandy Loam, which can dry out. Three sample areas never receive human watering (they can't because of location), which adds to dryness. 3. I don't know how these results should guide what I do for my Ailanthus -- can you advise? 4. There is one significant limb death since last year -- part of it was on its way out by last fall, and now the entire limb is gone. 5. As a late leafer, the leaves are just beginning to unfold, so I can't yet check for signs of verticillium wilt. Should I wait until the tree leafs out before I try something like deep-root fertilization? 6. She's still a good tree, even if she's on borrowed time, so I'd like to try something. I can afford to fertilize her roots myself.
Thank you,
Jane W.
Hi Jane -
If organic matter and nitrogen are low, these should be supplemented into the soil. (There is not really any way to decrease levels of 'high' nutrients, so don't worry about that). You can fertilize now with nitrogen. I would suggest any type of slow-release nitrogen fertilizer since it is a mature tree. The rate should be 2-3 lbs. of nitrogen per 1,000 ft2.
Organic matter is difficult to incorporate into the soil without damaging existing tree roots. Instead, you can apply a 2-3 inch layer of mulch made from organic matter. This will also help conserve soil moisture. Supplemental irrigation is very important for trees in Denver. Just be sure to keep the mulch not directly against the tree trunk. Removal of dead limbs is recommended for tree health and personal safety. Recommendations would be the same whether or not the tree has verticillium.
If organic matter and nitrogen are low, these should be supplemented into the soil. (There is not really any way to decrease levels of 'high' nutrients, so don't worry about that). You can fertilize now with nitrogen. I would suggest any type of slow-release nitrogen fertilizer since it is a mature tree. The rate should be 2-3 lbs. of nitrogen per 1,000 ft2.
Organic matter is difficult to incorporate into the soil without damaging existing tree roots. Instead, you can apply a 2-3 inch layer of mulch made from organic matter. This will also help conserve soil moisture. Supplemental irrigation is very important for trees in Denver. Just be sure to keep the mulch not directly against the tree trunk. Removal of dead limbs is recommended for tree health and personal safety. Recommendations would be the same whether or not the tree has verticillium.
OK, Alexis! Your answers and my research (especially by considering where I took soil samples) are really making a difference. In addition to the 3 sample areas that never receive human watering, two years ago I let a 160 sf area of grass under the drip line (of 1325 sf total) -- which I had watered regularly -- die off, then cleared it down to dirt. To protect from weeds and dust, last fall I put down black weed cloth. None of this was good for the Ailanthus! The timing coincides with our drought, and the Ailanthus' increased loss of limb and branch.
Here's my current plan, on which I invite your opinion:
I was going to remove the black cloth this summer anyway because the black would radiate so much heat, but I can't afford to landscape it. I will cover it and the three other non-waterable areas in organic mulch.
The other five sites are in living grass and garden areas. I fertilize and aerate the grass well and responsibly. In these areas, could I use something like the Yard Butler deep-root irrigator to water the roots, as well as to deliver the following fertilizer to the roots rather than topsoil:
The soil-sample report suggests adding urea, ammonium sulfate, bloodmeal, corn gluten meal, or alfalfa meal pellets along with the nitrogen. The report gives me the proportional amounts to add.
I found non-organic, non-slow release Urea - (NH2)2CO - 46-0-0 fertilizer produced from byproducts of coal, natural gas, and petroleum-derived materials, which sounds like a bad idea. Urea generally looks a little tricky.
Anyway, I'm anxious to get going. I bet my Ailanthus would benefit by nitrogen immediately -- however it's delivered -- and the mulch. I could add one of the other suggested products in a subsequent watering(s).
Assuming you think this is a viable plan -- with no guarantees -- how often should I deep-root water each root area, and how often should I add fertilizer to the irrigation?
Thanks so much, Alexis!
~Jane
Here's my current plan, on which I invite your opinion:
I was going to remove the black cloth this summer anyway because the black would radiate so much heat, but I can't afford to landscape it. I will cover it and the three other non-waterable areas in organic mulch.
The other five sites are in living grass and garden areas. I fertilize and aerate the grass well and responsibly. In these areas, could I use something like the Yard Butler deep-root irrigator to water the roots, as well as to deliver the following fertilizer to the roots rather than topsoil:
Slow Release Fertilizer with 100% Organic Nitrogen
I could also deep irrigate/fertilize the roots in the 160 sf dirt patch I'm going to cover with mulch. That area hasn't received any fertilizer in a good two years.
"____________ is an environmentally friendly, slow release fertilizer with 100% organic nitrogen. ___________ is made from a renewable nutrient source, making it a sustainable fertilizer that helps with nutrient recycling and enhances environmental quality. It can be used for all your gardening needs! __________ is easy to use! It does not have to be watered in and will not burn your plants."
The soil-sample report suggests adding urea, ammonium sulfate, bloodmeal, corn gluten meal, or alfalfa meal pellets along with the nitrogen. The report gives me the proportional amounts to add.
I found non-organic, non-slow release Urea - (NH2)2CO - 46-0-0 fertilizer produced from byproducts of coal, natural gas, and petroleum-derived materials, which sounds like a bad idea. Urea generally looks a little tricky.
Anyway, I'm anxious to get going. I bet my Ailanthus would benefit by nitrogen immediately -- however it's delivered -- and the mulch. I could add one of the other suggested products in a subsequent watering(s).
Assuming you think this is a viable plan -- with no guarantees -- how often should I deep-root water each root area, and how often should I add fertilizer to the irrigation?
Thanks so much, Alexis!
~Jane
Ah, in my haste yesterday, I see you recommend applying the nitrogen to the soil. I have a call in to my lawn guy to see if the product will burn the grass. I might go ahead and do the deep-root irrigation and slow-release nitrogen fertilization.
I've also settled on corn gluten meal to apply to the grass/soil. I'm also relying on my lawn guy's recommendation whether I can apply it to the grass now, or whether I should wait. The deep-root fertilization will have already reached the roots anyway.
I'm going to be conservative in my deep-root fertilization. Thanks, Alexis.
I've also settled on corn gluten meal to apply to the grass/soil. I'm also relying on my lawn guy's recommendation whether I can apply it to the grass now, or whether I should wait. The deep-root fertilization will have already reached the roots anyway.
I'm going to be conservative in my deep-root fertilization. Thanks, Alexis.
The suggestions of urea, ammonium sulfate, bloodmeal, corn gluten meal, or alfalfa meal pellets are just examples of different types of fertilizer you can use. I would use any slow-release nitrogen fertilizer. I would remove the black cloth. Fertilize and irrigate the entire area underneath the dripline. Fertilization can be done once in the spring, or split between the spring and fall in two applications. Spring is typically better for N fertilization in this climate.
During drought, trees grown in sites without lawn irrigation need 10 gallons of water each week per inch of trunk diameter measured. The trunk diameter measurement should be taken at 6 inches above the soil for a 1 to 4 inch diameter tree and at 12 inches above the soil for a tree with a diameter greater than 4 inches. A 2-inch diameter tree, therefore, requires 20 gallons of water per week.During the spring and summer months from May through September, water established trees weekly to two times per month depending on water restrictions, tree size and growth phase, weather, temperature, and soil conditions.During the fall and winter months from October through April, water established trees one to two times per month and only when the air temperature is above 40 degrees F and the soil is not frozen. The following fact sheet has more info. on watering:
http://www.ext.colostate.edu/pubs/garden/07240.html
During drought, trees grown in sites without lawn irrigation need 10 gallons of water each week per inch of trunk diameter measured. The trunk diameter measurement should be taken at 6 inches above the soil for a 1 to 4 inch diameter tree and at 12 inches above the soil for a tree with a diameter greater than 4 inches. A 2-inch diameter tree, therefore, requires 20 gallons of water per week.During the spring and summer months from May through September, water established trees weekly to two times per month depending on water restrictions, tree size and growth phase, weather, temperature, and soil conditions.During the fall and winter months from October through April, water established trees one to two times per month and only when the air temperature is above 40 degrees F and the soil is not frozen. The following fact sheet has more info. on watering:
http://www.ext.colostate.edu/pubs/garden/07240.html
OK, thanks for the specifics. I'm going to get right on it. You're a peach. ~Thanks, Jane
You're welcome and good luck!
Hi, Alexis: We got very good organic compost (my own and EKO brand) amended well into 1/2 of the dry 160-180sf patch on Monday. My helper dug deep rows into the parched soil. Because the empty patch is for my rental house in the back, and because of the slope of the dry patch, I have to do 1/2 at a time and manage odor as well. I placed a soaker hose on top, and for the time being only re-placed the black Weed-Bloc over it all. That way I can slow soak the mulched soil, and the black cloth blocks smell and run-off until it settles down. The weather is moderate now, and it's an eastern exposure covered by the leafing Ailanthus, so the black won't absorb too much heat and scorch it. Could sealing it for a while with the WeedBloc create and trap any harmful gases? It has a number of holes in it from previous use, but not enough if using it is harmful -- even in the short term. I can always punch more holes in the cloth.
All of it is below the drip line where watering and fertilization was discontinued 2-3 years ago.
My deep-root aeration tool and fertilizer dispenser have arrived. Fertilizer should arrive Friday. I am going to deliver some of the fertilizer about 6 inches deep, 12 to 24 inches apart, and will be conservative so as not to burn roots. I've requested a watering exemption from Denver Water.
While I was placing a border around the base of the Ailanthus to protect it from the compost-mulch (its diameter 12" above soil is about 30.5 inches), I noticed that from the base up to about 10 inches, a large piece of bark is so loose I could have easily pulled it off. At another point where a large root entered the ground, it was hollow and pushed in when I pressed on it.
The best-case scenario is that this is a result of, or made more severe by, the nutrient and moisture deficiencies the Ailanthus suffers from. I realize there are other scenarios.
I saved pieces of bark that had fallen off naturally. Can the Soil, Water and Testing Laboratory examine them to see if it reveals anything? Is the Ambrosia beetle visible, and could it be responsible? I see no evidence of any beetles, bugs, worms, etc.
Thanks! ~Jane W.
All of it is below the drip line where watering and fertilization was discontinued 2-3 years ago.
My deep-root aeration tool and fertilizer dispenser have arrived. Fertilizer should arrive Friday. I am going to deliver some of the fertilizer about 6 inches deep, 12 to 24 inches apart, and will be conservative so as not to burn roots. I've requested a watering exemption from Denver Water.
While I was placing a border around the base of the Ailanthus to protect it from the compost-mulch (its diameter 12" above soil is about 30.5 inches), I noticed that from the base up to about 10 inches, a large piece of bark is so loose I could have easily pulled it off. At another point where a large root entered the ground, it was hollow and pushed in when I pressed on it.
The best-case scenario is that this is a result of, or made more severe by, the nutrient and moisture deficiencies the Ailanthus suffers from. I realize there are other scenarios.
I saved pieces of bark that had fallen off naturally. Can the Soil, Water and Testing Laboratory examine them to see if it reveals anything? Is the Ambrosia beetle visible, and could it be responsible? I see no evidence of any beetles, bugs, worms, etc.
Thanks! ~Jane W.
It sounds like you are on the right track and doing everything for the tree. If bark is coming off the tree and roots are dead and hollow it may indicate that there is some decay. Root rot especially can predispose a tree to windthrow. There is nothing that can be done about decay in trees except maintaining or improving overall tree health and making sure that it is not at risk of failure.
Hi, Alexis: Thanks.
There's bad news and good news. The Ailanthus lost much more ground than I first thought. She is now about 33% of herself from 22 years ago. There are many more branches and a few more limbs bearing no foliage.
However! I've been treating her for 2-1/2 weeks now via all the ways I described above. New growth on her bottom third leafed out pretty healthy (most of this third is the trunk). Some new growth has grown off of limbs that look dead higher up. The leaves on the top 2/3 were terribly sad, but I don't think I'm seeing things to say they have perked up considerably since I've been treating her. I have the advantage of comparing her to two Ailanthus trees right behind her in my neighbor's yard -- those two trees grew up off of the sucker shoots of my Ailanthus. I compare my tree's leaves to those of the young trees.
Assuming she is stabilizing, how long should I wait to have dead limbs and branches removed, and to have her pruned for maximum health? I assume she needs more recovery time. I can see that if she continues improving, she will look and be so much better. I can picture new growth as was her trend for so many years.
Also, because my neighbor let sucker shoots grow into a couple trees, could they have sapped nutrients from my tree? He also let a couple volunteer trees next to her on his side of the fence mature into trees that are about 2/3 her height. I wonder if they pulled nutrients as well.
Thanks so much,
Jane
There's bad news and good news. The Ailanthus lost much more ground than I first thought. She is now about 33% of herself from 22 years ago. There are many more branches and a few more limbs bearing no foliage.
However! I've been treating her for 2-1/2 weeks now via all the ways I described above. New growth on her bottom third leafed out pretty healthy (most of this third is the trunk). Some new growth has grown off of limbs that look dead higher up. The leaves on the top 2/3 were terribly sad, but I don't think I'm seeing things to say they have perked up considerably since I've been treating her. I have the advantage of comparing her to two Ailanthus trees right behind her in my neighbor's yard -- those two trees grew up off of the sucker shoots of my Ailanthus. I compare my tree's leaves to those of the young trees.
Assuming she is stabilizing, how long should I wait to have dead limbs and branches removed, and to have her pruned for maximum health? I assume she needs more recovery time. I can see that if she continues improving, she will look and be so much better. I can picture new growth as was her trend for so many years.
Also, because my neighbor let sucker shoots grow into a couple trees, could they have sapped nutrients from my tree? He also let a couple volunteer trees next to her on his side of the fence mature into trees that are about 2/3 her height. I wonder if they pulled nutrients as well.
Thanks so much,
Jane
It sounds like the tree may have been declining for some time, despite your best efforts. If there is rot, decay, and extensive canopy dieback it could be a hazardous situation and should be evaluated for its risk of failure. An ISA Certified Arborist can tell you whether or not it needs to come down. You can find one here:
http://www.isa-arbor.com/faca/findArborist.aspxl
http://www.isa-arbor.com/faca/findArborist.aspxl
OK, thanks. I've talked with one certified arborist/tree worker climber specialist, and am waiting to hear back with estimates from two others. Meanwhile, I'll keep taking care of the tree.
~Jane
~Jane
Sounds like a plan!
Hi, Alexis,
As I write, the Ailanthus is being cut down. THANK YOU for your sage and responsive advice from trying to save the tree to sending names of arborists with the recommendation I have it assessed.
At about 12" from the ground, the arborist determined the trunk was about 70%
rotted. It's at the end of its life cycle. My sadness at losing the tree was overcome by my concern for hazard. I can't afford it, but I can't afford not to have it removed.
I'm going to plant a new tree this fall, and this time I can place it more optimally. I'm looking for a drought resistant, moderate-growth (speed) tree. (I'd go for a slow grower, but the sun makes both my home and the rental house at back scorching hot in summer.)
Someone suggested a seedless Linden. Is that a good choice for a back yard in Denver with the criteria I mentioned? Do you have material with suggested trees for the Rocky Mountain clime in the city?
Thank you!
Jane
As I write, the Ailanthus is being cut down. THANK YOU for your sage and responsive advice from trying to save the tree to sending names of arborists with the recommendation I have it assessed.
At about 12" from the ground, the arborist determined the trunk was about 70%
rotted. It's at the end of its life cycle. My sadness at losing the tree was overcome by my concern for hazard. I can't afford it, but I can't afford not to have it removed.
I'm going to plant a new tree this fall, and this time I can place it more optimally. I'm looking for a drought resistant, moderate-growth (speed) tree. (I'd go for a slow grower, but the sun makes both my home and the rental house at back scorching hot in summer.)
Someone suggested a seedless Linden. Is that a good choice for a back yard in Denver with the criteria I mentioned? Do you have material with suggested trees for the Rocky Mountain clime in the city?
Thank you!
Jane
Hi Jane -
Well, if it had a lot of heart rot in its center, then I am glad you took it down before it fell down! We have a number of fact sheets on trees for Colorado on our site:
http://www.ext.colostate.edu/pubs/pubs.html
Linden is a good tree, but not quite as drought-tolerant as others. Other factors to consider are mature size of tree, proximity of buildings and utility wires, deciduous or evergreen, pest issues, etc.
Well, if it had a lot of heart rot in its center, then I am glad you took it down before it fell down! We have a number of fact sheets on trees for Colorado on our site:
http://www.ext.colostate.edu/pubs/pubs.html
Linden is a good tree, but not quite as drought-tolerant as others. Other factors to consider are mature size of tree, proximity of buildings and utility wires, deciduous or evergreen, pest issues, etc.
