Quercus robur leaves. Slight chlorosis?

[EPM]

Does anybody else think the leaves in the picture show some signs of slight chlorosis? Or am I just being paranoid? I don't have a lot of experience with oaks but the ones I've seen in my yard and the forest around my yard do not look like this. Admittedly this is a different species but the appearance is weird to me. Thanks for your input.

 

[Leo in N E Illinois]

Yes, looks a mild case of chlorosis. It can happen during periods of extremely rapid growth. Often will green up as growth slows. Or if you give a dose of what it is missing.

My first go to is to do one watering every 2 months with 1 to 2 teaspoons per gallon magnesium sulfate solution. The both the magnesium and the sulfur of the sulfate are required nutrients. Magnesium is needed for proper chlorophyll development. Sulfate is usually not present in liquid fertilizers because it will for insoluble salts with other fertilizer components (esp a fertilizer with calcium).

Magnesium sulfate is available as Epsom Salts from your local pharmacy. Used as a bath salt to soak feet and other body parts. Should be no more than a dollar per pound. Usually sold in 3 pound bags. Dr Teals is the brand at my local Walmart.

If two weeks after a dose of Epsom salts the color has not greened up, time to Iron your plant.
Use a commercial Iron Fertilizer, such as Ironite. Usually can find it at landscape nurseries, it is not usually stocked by big box stores. It will supplement iron and manganese (not magnesium) as the sulfate or the EDTA chelate of both metals. Read label, usually a teaspoon to a tablespoon per gallon is about right. But READ LABEL use recommended dose to one half the recommended dose, don't over do it. More is not better.

Long term solution - Oaks are known to generally like somewhat acidic soils, much like azaleas, though oaks are more adaptable on this than azalea. Add more composted bark to your potting mix. You can additionally mix in elemental sulfur - found at old fashioned nurseries where they cater to vegetable growers. Elemental sulfur comes in 2 grades - as a soil acidifier in which case it is a sand like powder - 1 tablespoon (15 ml by vol) per nursery can gallon of potting media. Repeat this dose once a year. The other grade of elemental Sulfur is the ultra fine powder sold as a spray on fungicide. (grape growers in particular use it). This fine powder will dissolve much faster than the soil acidifier grade of Sulfur. So you use roughly one third the amount and apply it 3 times a year. As the sulfur dissolves, it creates weak sulfonic acid, and only tiny amounts of the stronger sulfuric acid. Under normal back yard conditions sulfur will not harm you trees even if accidentally overdosed.
The sulfur itself is a required macronutrient, and as it dissolves the sulfur also acidifies the soil allowing the tree to absorb magnesium, iron and manganese more efficiently. You are in Ohio, your soils are largely derived from limestone, and water from your aquifers will tend to be alkaline from the limestone, so the added sulfur will at least partly counteract these factors.

 

[TomB]

In addition to Leo’s advice, I associate that kind of colouring with the development of powdery mildew (before the telltale white appears). I would also spray with a fungicide if you’re not already doing that.

 

[EPM]

Yes, looks a mild case of chlorosis. It can happen during periods of extremely rapid growth. Often will green up as growth slows. Or if you give a dose of what it is missing.

My first go to is to do one watering every 2 months with 1 to 2 teaspoons per gallon magnesium sulfate solution. The both the magnesium and the sulfur of the sulfate are required nutrients. Magnesium is needed for proper chlorophyll development. Sulfate is usually not present in liquid fertilizers because it will for insoluble salts with other fertilizer components (esp a fertilizer with calcium).

Magnesium sulfate is available as Epsom Salts from your local pharmacy. Used as a bath salt to soak feet and other body parts. Should be no more than a dollar per pound. Usually sold in 3 pound bags. Dr Teals is the brand at my local Walmart.

If two weeks after a dose of Epsom salts the color has not greened up, time to Iron your plant.
Use a commercial Iron Fertilizer, such as Ironite. Usually can find it at landscape nurseries, it is not usually stocked by big box stores. It will supplement iron and manganese (not magnesium) as the sulfate or the EDTA chelate of both metals. Read label, usually a teaspoon to a tablespoon per gallon is about right. But READ LABEL use recommended dose to one half the recommended dose, don't over do it. More is not better.

Long term solution - Oaks are known to generally like somewhat acidic soils, much like azaleas, though oaks are more adaptable on this than azalea. Add more composted bark to your potting mix. You can additionally mix in elemental sulfur - found at old fashioned nurseries where they cater to vegetable growers. Elemental sulfur comes in 2 grades - as a soil acidifier in which case it is a sand like powder - 1 tablespoon (15 ml by vol) per nursery can gallon of potting media. Repeat this dose once a year. The other grade of elemental Sulfur is the ultra fine powder sold as a spray on fungicide. (grape growers in particular use it). This fine powder will dissolve much faster than the soil acidifier grade of Sulfur. So you use roughly one third the amount and apply it 3 times a year. As the sulfur dissolves, it creates weak sulfonic acid, and only tiny amounts of the stronger sulfuric acid. Under normal back yard conditions sulfur will not harm you trees even if accidentally overdosed.
The sulfur itself is a required macronutrient, and as it dissolves the sulfur also acidifies the soil allowing the tree to absorb magnesium, iron and manganese more efficiently. You are in Ohio, your soils are largely derived from limestone, and water from your aquifers will tend to be alkaline from the limestone, so the added sulfur will at least partly counteract these factors.

Thanks for the advice. I will give this a shot and see how things go. I suspect the issue is my water. We have not had a lot of rain lately and it has been very hot so I'm watering with well water more than usual. I'm aiming to get a rainwater collection system setup this summer so I'm hoping that along with the advice you've provided will mitigate the issue. Thanks again!

 

[EPM]

In addition to Leo’s advice, I associate that kind of colouring with the development of powdery mildew (before the telltale white appears). I would also spray with a fungicide if you’re not already doing that.

Very interesting. Do you think the powdery mildew is taking advantage of the trees in a weakened state(because of ph and mineral imbalances) or do you believe the powdery mildew causes this? I will treat with a copper based fungicide as well.

 

[TomB]

Very interesting. Do you think the powdery mildew is taking advantage of the trees in a weakened state(because of ph and mineral imbalances) or do you believe the powdery mildew causes this? I will treat with a copper based fungicide as well.

I don’t know the answer to that one. It may be coincidence, as Quercus robur is very susceptible to mildew in any case.

 

[papymandarin]

sulfur is better preventative fungicide against oidium than a copper based one in my opinion

 

[EPM]

Yes, looks a mild case of chlorosis. It can happen during periods of extremely rapid growth. Often will green up as growth slows. Or if you give a dose of what it is missing.

My first go to is to do one watering every 2 months with 1 to 2 teaspoons per gallon magnesium sulfate solution. The both the magnesium and the sulfur of the sulfate are required nutrients. Magnesium is needed for proper chlorophyll development. Sulfate is usually not present in liquid fertilizers because it will for insoluble salts with other fertilizer components (esp a fertilizer with calcium).

Magnesium sulfate is available as Epsom Salts from your local pharmacy. Used as a bath salt to soak feet and other body parts. Should be no more than a dollar per pound. Usually sold in 3 pound bags. Dr Teals is the brand at my local Walmart.

If two weeks after a dose of Epsom salts the color has not greened up, time to Iron your plant.
Use a commercial Iron Fertilizer, such as Ironite. Usually can find it at landscape nurseries, it is not usually stocked by big box stores. It will supplement iron and manganese (not magnesium) as the sulfate or the EDTA chelate of both metals. Read label, usually a teaspoon to a tablespoon per gallon is about right. But READ LABEL use recommended dose to one half the recommended dose, don't over do it. More is not better.

Long term solution - Oaks are known to generally like somewhat acidic soils, much like azaleas, though oaks are more adaptable on this than azalea. Add more composted bark to your potting mix. You can additionally mix in elemental sulfur - found at old fashioned nurseries where they cater to vegetable growers. Elemental sulfur comes in 2 grades - as a soil acidifier in which case it is a sand like powder - 1 tablespoon (15 ml by vol) per nursery can gallon of potting media. Repeat this dose once a year. The other grade of elemental Sulfur is the ultra fine powder sold as a spray on fungicide. (grape growers in particular use it). This fine powder will dissolve much faster than the soil acidifier grade of Sulfur. So you use roughly one third the amount and apply it 3 times a year. As the sulfur dissolves, it creates weak sulfonic acid, and only tiny amounts of the stronger sulfuric acid. Under normal back yard conditions sulfur will not harm you trees even if accidentally overdosed.
The sulfur itself is a required macronutrient, and as it dissolves the sulfur also acidifies the soil allowing the tree to absorb magnesium, iron and manganese more efficiently. You are in Ohio, your soils are largely derived from limestone, and water from your aquifers will tend to be alkaline from the limestone, so the added sulfur will at least partly counteract these factors.

Leo,
I forgot to add before that I do have pine bark in my mix. In fact one oak, a quercus lobata I bought from Brent at Evergreen Garden works, is in a 50/50 mix of bark and perlite. It is also showing some signs of chlorosis but probably more mild than the picture.

I checked yesterday and a Japanese beech I have might also be showing some signs. Maybe not surprising considering beech and oak are related.

Have you ever used iron-tone from espoma? If you were building a soil mix from scratch for a temperate deciduous oak what would you use?

I treated the trees with magnesium sulfate solution yesterday. I'll let you know how they do. Thanks again.

 

[Leo in N E Illinois]

Epsoma has a good reputation, I have never used it, but I assume it would be good.

 

[Leo in N E Illinois]

I forgot to mention, nitrogen deficiency can also cause chlorosis, so 3 different nutrients can cause chlorosis. Under alkaline conditions, nitrogen uptake is blocked, just as iron uptake.

Use a high nitrogen fertilizer,. 30-10-30 is good, 12-1-14 is actually better, MSU formula.