Yellowing larches

[Cable]

Dale Harder, a former president of the Cleveland Bonsai Club and a 40+ year bonsai practitioner (and also my first bonsai teacher) is having a problem with his larches that he can't quite figure out. I'm trying to help him.

Every time I've seen his larches they've been a bright yellow and he can't seem to get it to change. I asked him some questions for more information (his answers are bold) and I've posted some pics below.

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I'm back in town! I've been thinking about your yellowing problem with your larches and I'd like to try to help. When you get a free minute, would you please send me some information?

Specifically, what are the trees? Larix decidua? Larix kaempferi? Larix occidentalis? Larix laricina? Pseudolarix amabilis? Larix Larcina. Most of my specimens were collected at the top of the Bruce Penninsula in Canada

When did you first notice the problem? This has been going on for years. These trees come from some of the harshest conditions and while really a bog tree they do grow in rock crevices and scrub.

Do the new needles come out yellow or are they green at first and then turn yellow? Beginning growth is always nice and green. Yellows after 3 to 4 months, but depends on how hot it has been. Part of it may be stress.

What have you tried to do about it? More water, less water, occasionally lime the soil, once every 3 months or so. add Chelated Iron, Epsom salts, etc. Different fertilizers. Also tried adding microizza, changing soils .

How old are the trees? From 40 to 150 yrs old.

When did you last repot them? I repot about every 2 to 3 years, depending on how old the tree is. Older, less potting.

What is your soil mix? I have tried pure Akadama, Akadama mix with Granite chips or Pumice and Bark. Now I use mostly Granite and Bark. I prefer a fast draining soil.

What is your fertilizer regimen? Once every 2 weeks during the growing season. I use 10-10-10 or 20-20-20 and cut them heavily with water. Sometimes I use Osmacote or slow release. For the flowering trees I use a mix to promote flowering and a mix for after flower to recoup.

Any other information you think would be helpful would be appreciated. I note that about 5 years ago I had a very severe yellowing and die off on all my Juniper. Juniperus Sargenti. Nothing I did could save them. Every tree, eventually yellowed, died back and eventually succumbed. I believe it was a fungus or root rot, but nothing worked. I even tried the state Horticultural folks...no help. The last few yeas I have seen various elements of yellowing on my pines as well. I do believe it is stress related and temperature. As you know, watering is a very fussy ordeal.

I do water with cleveland city water. Which tends to be really nasty. If you boil a pot of water on the stove you are left with an insideous ring of hard deposits that you can not scrub off. I wish I could find something to remove the lime and rust deposits, but nothing works. Unfortunately, I can not easily water by collecting 50 gallon drums and letting it sit. I would go through a barrel a day.
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I would appreciate any suggestions I can pass along.

 

[Wilson]

I would think @twisted trees is the specialist with larch, also @Mark .

 

[WNC Bonsai]

Larch normally grow in acidic soils so I am thinking all this lime you are using along with what is likely a high pH, alkaline city water is at least part of the problem. I would be watering with rain water and using something like Miracid or soil acidifer. Check with your local water supplier to get a water chemistry printout, mine sends me one each year, and take it to your local ag service people and find out how you can treat it to use on conifers.

 

[Wires_Guy_wires]

Has he checked for insects? Root bound trees? Watering too often? Things that are easily overlooked sometimes by experts, because generally it doesn't happen to them.

I'm betting there might even be some antibiotics at play, overdosing those will cause yellowing and eventually result in death.

One other thing that comes to mind; water pH. During the winter months, the tapwater pH lowers in my village simply because there's more rainfall adding to the circulation. During summer, it rises again because of the recycling of tap water. This might explain why they start out green, and turn yellow later.
I see the pH of my pots rise over the summer, and being lowered by rainfall and lowered tapwater during fall, winter and spring.

 

[WNC Bonsai]

In the US municpal water supplies are treated to be neutral to slightly alkaline, helps to prevent leaching of trace metals from water pipes. So even where I live although our annual rainfall has an average pH down about 5.2 and is collected in large reservoirs in the mountains, by the time it is treated and reaches my tap it is back up around pH 7. I collect and use rainwater for some of my really sensitive carniverous plants and use soil aicidifier on most of my trees to counter this.

 

[JudyB]

Do any other people in the same vicinity that have larch have any of these same issues? I would think that would be a way to start detecting what the issue is.

 

[GGB]

I think @Cofga might be onto something. My larch have yellowed after being water logged but it sounds like this guy is using a pretty fast draining soil. And by water logged I mean I went on vacation for 5 days and submegred the pots haha. they never look right after that

 

[coh]

Do any other people in the same vicinity that have larch have any of these same issues? I would think that would be a way to start detecting what the issue is.

This would be a good place to start!

Is the guy living in the Cleveland area or elsewhere in Ohio? I would think larch should do fine in Cleveland but maybe not so well in southern Ohio. If it's Cleveland, the water source is
probably Lake Erie (we use Lake Ontario so probably similar). I would have the water tested or at least check what the water company is reporting, they should be publishing water test
results at least once or twice a year.

Root aphids is another possibility I thought of, seems that is a growing problem around the country.

 

[Oleg]

Same on the junipers and pines, was the timing similar in the yellowing and death?

 

[Forsoothe!]

In addition to liking bogs, Tamarack hates hot roots and that's why they don't range much below Midland, Michigan. They want all day sun and cool roots, and the further south you get, the harder that is to maintain. I agree that you should check the pH, but start with the mix in the pot, which shouldn't be too shallow or dark colored. If it's on a slab trapped by high pH clay, that could affect the situation. Yellow foliage is the normal color of autumn's used-up leaves, so maybe the plant is too tired early in the year by a combination of high root temps, pH, and running dry too often? If the location is coincidentally shaded in the afternoon by trees or structures due to the sun moving more northwesterly by August, that could hurt, too, especially if, because of your location, you have it leaf-out earlier than typical, let's say by early April. That might move the end-of-season closer to ~August 21st, rather than ~September 21st. Since Tamarack are northerly trees, they have a shorter growing season programed in. If you are getting cones, and they are openning in August, that would indicate that the tree is sucessfully ending the growing season. (Tamarack produce seed by 40 years of age). I'm speculating, of course, but this sounds like a problem with several contributing factors rather than one, single problem.

 

[Vance Wood]

I have not noticed anyone bringing this point up and it seems to me to be beyond mentioning but-----You know Larch are deciduous and will lose their needles in and around Oct. every year They trun various shades of Yellow, then---- they turn loose and go as naked as a Maple for the rest of the year.

 

[Mike Hennigan]

My guess is also a a pH problem.

 

[Soldano666]

I have not noticed anyone bringing this point up and it seems to me to be beyond mentioning but-----You know Larch are deciduous and will lose their needles in and around Oct. every year They trun various shades of Yellow, then---- they turn loose and go as naked as a Maple for the rest of the year.

Right? Problem starts to happen after 3 or 4 months after new bright green growth???

 

[Cable]

Do any other people in the same vicinity that have larch have any of these same issues? I would think that would be a way to start detecting what the issue is.

Not that I've noticed.

This would be a good place to start!

Is the guy living in the Cleveland area or elsewhere in Ohio? I would think larch should do fine in Cleveland but maybe not so well in southern Ohio. If it's Cleveland, the water source is
probably Lake Erie (we use Lake Ontario so probably similar). I would have the water tested or at least check what the water company is reporting, they should be publishing water test
results at least once or twice a year.

Root aphids is another possibility I thought of, seems that is a growing problem around the country.

Yes, he lives in a suburb of Cleveland.

I have not noticed anyone bringing this point up and it seems to me to be beyond mentioning but-----You know Larch are deciduous and will lose their needles in and around Oct. every year They trun various shades of Yellow, then---- they turn loose and go as naked as a Maple for the rest of the year.

That is true. The first pic was taken in September but the others were taken in April. The first time I saw them was in August the previous year and they were yellow then, too.

Thank you, everyone. I will pass this along and let you know if there is improvement this year.

 

[Mike Hennigan]

Just read over it again and saw it’s hapoening with his pines as well. I feel like that’s a good argument for a pH issue. Since it’s happening to quite different species. The quick and dirty explanation is that if the pH is too off the tree will suffer nutrient deficiencies because it cannot access those nutrients from the soil any longer. Using something like chelated iron is like using a band-aid. It may green the tree up temporarily but it does not cure the problem. He should concentrate on getting the soil more acidic and see if that helps, and test his water pH as well. Does he fertilize with liquid chemical type stuff or organics? Using good organic fertilizer will help make the soil environment more acidic. My 2 cents.

 

[coh]

Just read over it again and saw it’s hapoening with his pines as well. I feel like that’s a good argument for a pH issue. Since it’s happening to quite different species. The quick and dirty explanation is that if the pH is too off the tree will suffer nutrient deficiencies because it cannot access those nutrients from the soil any longer. Using something like chelated iron is like using a band-aid. It may green the tree up temporarily but it does not cure the problem. He should concentrate on getting the soil more acidic and see if that helps, and test his water pH as well. Does he fertilize with liquid chemical type stuff or organics? Usinggoid irganic fertilizer will help make the soil environment more acidic. My 2 cents.

Don't just test the water pH, though, you need to also test for alkalinity and types of dissolved substances. Those can accumulate in the container and over time raise the pH in the container.

FWIW, I've had a couple of trees over the years that exhibit what I call "early fall" syndrome, meaning the leaves start turning autumn color way earlier in the summer than they should...like July or August. It has happened on a euonymus, a Sango Kaku maple, and tilia. The tilia is now in the ground where it is not showing the same symptoms (big clue there). The other two still show the same problem to varying
degrees each summer. I haven't been able to figure out the cause but it might be similar to what the OP is dealing with.

 

[Cable]

In addition to liking bogs, Tamarack hates hot roots and that's why they don't range much below Midland, Michigan. They want all day sun and cool roots, and the further south you get, the harder that is to maintain.

Winner winner chicken dinner. I heard back from him yesterday and after trying various things he finally hit on the plants being too hot. He was going for full sun since larch like that but wasn't taking steps to cool the soil. He moved them to part shade and they all greened up again.

Thanks everyone!