Sweetgum Chlorosis

[Gabler]

My sweetgum trees are looking yellow—well, some of them, anyway. It’s a forest planting with some green leaves and some yellow.

I noticed some of the leaves were looking yellow when they first emerged. I immediately fertilized with both Osmocote and a kelp-based liquid fertilizer. The trees have all continued to grow at the same rate, but some of them are continuing to produce yellow leaves and others are still producing green leaves.

I’m not sure what the problem is. The soil is a blend of leftover kiryuzuna soil, perlite, vermiculite, and a tiny bit of peat. The pot has had a lot of weeds, but I pull them daily. The weeds’ vigor leads me to think the soil is healthy. Any thoughs on what might be causing this?

This picture is from a month ago. The leaves are more plentiful now, but the same color on each respective tree.

 

[nuttiest]

I think if it is lower eaves it is nitrogen, the tree is making food for itself, and also gives up nitrogen to new leaves.

 

[milehigh_7]

My sweetgum trees are looking yellow—well, some of them, anyway. It’s a forest planting with some green leaves and some yellow.

I noticed some of the leaves were looking yellow when they first emerged. I immediately fertilized with both Osmocote and a kelp-based liquid fertilizer. The trees have all continued to grow at the same rate, but some of them are continuing to produce yellow leaves and others are still producing green leaves.

I’m not sure what the problem is. The soil is a blend of leftover kiryuzuna soil, perlite, vermiculite, and a tiny bit of peat. The pot has had a lot of weeds, but I pull them daily. The weeds’ vigor leads me to think the soil is healthy. Any thoughs on what might be causing this?

This picture is from a month ago. The leaves are more plentiful now, but the same color on each respective tree.

View attachment 485926

They like quite a low PH. Acidify with your favorite technique. Sulfer is good but slow. Perhaps a few doses of miracid to pep it up.

 

[hemmy]

I noticed some of the leaves were looking yellow when they first emerged. I immediately fertilized with both Osmocote and a kelp-based liquid fertilizer. The trees have all continued to grow at the same rate, but some of them are continuing to produce yellow leaves and others are still producing green leaves

I have a hard time nailing down deficiencies based on color and pattern, but the below link has some good info. If you’ve fertilized, Nitrogen shouldn’t be low. Remember Osmocote is temp dependent so be careful about piling it on prior to warmer weather. It breaks down in 3-4 months at 70F but only 1-2 months at 80F.

You could try foliar feeding to temporarily correct the issue and figure out which nutrient is the culprit.

A google search of sweet gum and deficiency showed an iron deficient leaf that looks like your picture.

Let’s see the whole planting. Only certain trees or portions are impacted? Maybe it is indicating compromised roots on some trees or pockets of poor soil (too wet/dry).

https://agsci.oregonstate.edu/sites/agscid7/files/horticulture/osu-nursery-greenhouse-and-christmas-trees/Octoberpest%2006%20Mineral%20Nutrient%20Defeciencies.pdf

 

[Gabler]

I think if it is lower eaves it is nitrogen, the tree is making food for itself, and also gives up nitrogen to new leaves.

The lower leaves, which emerged first, are green. The newer upper leaves are yellow with green veins as pictured.

 

[Gabler]

They like quite a low PH. Acidify with your favorite technique. Sulfer is good but slow. Perhaps a few doses of miracid to pep it up.

I figured adding a bit of peat would acidify the soil, but something else could be inadvertently raising the pH. I have Holly Tone that I use to fertilize roses and azaleas. I‘ll try it out once the Osmocote has had time to break down.

 

[Gabler]

Remember Osmocote is temp dependent so be careful about piling it on prior to warmer weather. It breaks down in 3-4 months at 70F but only 1-2 months at 80F.

We’ve had an unusually cold March and April. Temperatures have been consistently below 60°F. Could it be the case that the effect of the Osmocote has been delayed? Might it need more time to break down?

 

[Gabler]

Let’s see the whole planting. Only certain trees or portions are impacted? Maybe it is indicating compromised roots on some trees or pockets of poor soil (too wet/dry).

Only two trees near the edge of the planting are effected. As I mentioned just a moment ago, the lower leaves, which emerged first, are green. The newer upper leaves are yellowed.

Based on everyone’s input thus far, my suspicion is that it’s an iron deficiency due to low acidity.

That said, the fact that it’s only two trees near the edge of the planting also leads me to suspect the roots were damaged by freezing or something. Thinking about it now, it’s the two trees that were most exposed to the air over the winter.

 

[milehigh_7]

The thing about the nutrients its craving is they won't be soluble above a certain PH which is what you are seeing. However, the answer to the temperature question is yes temperature affects the rate that the osmocote works.

 

[Maiden69]

I don't about acidifying the soil for any of my trees... I tried once with azaleas and didn't see any difference in growth. My Liquidambar O. does great, and it is planted on inorganic soil. Bonsai Jack Monto Clay and Bonsai Block 1:1, fertilizer is Osmocote Plus every few weeks and Miracle Grow every 1-2 weeks. I do supplement once every 2 weeks with kelp/humic/fulvic acid, plus CalMag from NPK Industries RAW.

 

[Gabler]

I don't about acidifying the soil for any of my trees...

I do supplement once every 2 weeks with kelp/humic/fulvic acid…

I’m not sure I understand. Do you add acid or not?

 

[Gabler]

The thing about the nutrients its craving is they won't be soluble above a certain PH which is what you are seeing. However, the answer to the temperature question is yes temperature affects the rate that the osmocote works.

I had used Osmocote sparingly, since it tends to kill moss, so I felt comfortable adding a light dusting of Holly Tone. I’ll hold off on putting any further salts in the soil for a while and hope things improve in the coming weeks.

 

[Maiden69]

I’m not sure I understand. Do you add acid or not?

no. I guess I deleted a word.

I don't WORRY about acidifying the soil for any of my trees...

 

[Gabler]

Holly Tone seems to have fixed the problem. The new leaves are emerging green.

 

[hemmy]

We’ve had an unusually cold March and April. Temperatures have been consistently below 60°F. Could it be the case that the effect of the Osmocote has been delayed? Might it need more time to break down?

Glad to hear the Hollytone worked. It does sound like the Osmocote wasn’t providing much nutrients yet at your lower temps. But it should be broken down in a few months at warmer temps. I tend to use it mixed with the soil on developmental material repots and again on the surface of things in development. But I’ve been trying to move to more organics and liquid feedings for things in refinement.

 

[Gabler]

Glad to hear the Hollytone worked. It does sound like the Osmocote wasn’t providing much nutrients yet at your lower temps. But it should be broken down in a few months at warmer temps. I tend to use it mixed with the soil on developmental material repots and again on the surface of things in development. But I’ve been trying to move to more organics and liquid feedings for things in refinement.

I’m not sure how much it was an issue of temperature and how much it was an issue of acidity. My oaks were also showing signs of chorosis, but it was very mild. My beeches are fine, but they were potted with a little bit of leaf litter from near where they were collected. I’m leaning toward acidity as the issue. City water needs to be alkaline to prevent contamination from lead pipes, and I’m accustomed to well water. Maybe that was the source of the problem? I’ll have to watch carefully going forward to determine what the cause might have been.

 

[hemmy]

City water needs to be alkaline to prevent contamination from lead pipes, and I’m accustomed to well water. Maybe that was the source of the problem?

Most likely. Depending on your rainfall, the irrigation water will drive your substrate pH. In SoCal with 5-10” of rain a year and moderately alkaline water, I had to acidify the water for many deciduous species. It even seemed to help the vigor of the elms.

Now in the Midwest with slightly better, but still hard water, I am hoping that 40” annual rainfall and acidic fertilizers will help mitigate any issues.

Get your water district’s Water Quality Report and post it or the link and we can help interpret.

Here is the table (link below) that I use for water quality guidelines.


Post in thread 'Reading the Tree Leaves'
https://www.bonsainut.com/threads/reading-the-tree-leaves.51945/post-897695

 

[Gabler]

That table should be helpful if I run into further problems. Thanks!