Leaves turning yellow is a phenomenon called chlorosis. At the most fundamental level it is a lack of chlorophyll (the green part of the leaf) so you see the yellow pigment.
There are many reasons for why this would happen but it is a symptom of stress. In Bluberries a leading cause of chlorosis is iron deficiency.
This is from Kansas State
“Affected leaves turn a yellowish color while the leaf veins remain a dark green. Iron chlorosis is caused by the plant not being able to obtain the iron it needs. Iron is needed for the
production of chlorophyll and therefore, a lack of iron results in a loss of the green color in the leaves. In severe cases, leaf color may change from yellow to white to brown. Blueberries are especially susceptible because they require an acid pH (4.8 – 5.2 is best).”
You should do a soil test to rule this out.
Since your plants are in pots it is possible that the soil has become depleted. Re-potting them would allow you to provide fresh nutrients and examine the roots. Is the plant root bound? (i..e growing up against the side?)
- Cornell University
- Leaves are:
- Leaves are light green
- Leaves are yellow: Yellowing is interveinal, not associated with browning
- Leaves are yellow: Yellowing is interveinal, associated with browning
- Leaves are yellow: Yellowing is veinal, may be associated with browning
- Leaves are reddish-purple or maroon
- Leaves are red: Reddening is interveinal
- Leaves are red: Red spots are on the upper leaf surface only
- Leaves are whitish
- Blueberry’s Yellow leaves
- Yellow Leaves on Blueberry Bushes
- Reasons For Blueberry Chlorosis – Tips On Blueberry Chlorosis Treatment
- Reasons for Blueberry Chlorosis
- Blueberry Chlorosis Treatment
- Yellowing is interveinal, not associated with browning
- Yellowing is interveinal, associated with browning
- Yellowing is veinal, may be associated with browning
Reddish-purple or maroon
Red or have red spots:
- Reddening is interveinal
- Red spots are on the upper leaf surface only
Leaves are light green
Light green leaves may indicate a lack of nitrogen. nitrogen deficiencies are common in blueberries. Note the light green color (chlorosis) is uniform across the leaves with no particular pattern or mottling. (Below: Nitrogen deficiency on ‘Bluecrop’ blueberry. Plant on the left did not receive adequate nitrogen fertilizer.) Other symptoms of nitrogen deficiency include reduced shoot growth, numbers of new canes and yield. Nitrogen deficient leaves may develop early fall color and then drop off.
More blueberry nutrient deficiency information.
Leaves are yellow: Yellowing is interveinal, not associated with browning
Interveinal yellowing is caused by iron deficiency, but is symptomatic of high soil pH. A high soil pH (>5.2) results in the inability of the blueberry plant to use iron, causing a lack of chlorophyll production.
Iron deficiency symptoms develop first in young leaves. Lowering the pH with sulfur will usually correct the problem.
More iron deficiency information.
Leaves are yellow: Yellowing is interveinal, associated with browning
A number of causes can induce leaf browning in blueberries. Many of these are associated with factors contributing to overall cane death or dieback.
If canes are not dying but leaves on particular portions of the plant are turning brown, the cause could be
- Herbicide Injury
- Botrytis Stem and Leaf Blight
- Mummy Berry Shoot Blight,
- Potassium Deficiency
- Drought Stress.
Herbicide injury from preemergent materials is usually accompanied by leaf yellowing or bleaching, followed by browning, and tends to be interveinal. More herbicide injury information.
Below: Sinbar (terbacil) herbicide damage
Below: Princep (simazine) herbicide damage
Botrytis Stem and Leaf Blight – This fungus affects leaves and shoots during damp, cool springs (below). More botrytis blight and fruit rot information
Mummy Berry Shoot Blight – Leaves become necrotic and are covered with powdery masses of gray spores during wet weather (below). More mummy berry information
These primary shoot blight infections occur when spores are rain splashed and wind carried from mushrooms cups developing from mummfied fruit on the ground under bushes (below).
Potassium Deficiency – K deficiency results in marginal leaf burn (below). It is not common, but has been observed in very sandy soils. More nutrient deficiency information
Overfertilization – Overfertilization also causes marginal leaf burn. In young plants, too much fertilizer can lead to death.
Drought Stress can cause browning of blueberry leaves. Water demand for blueberries is typically highest in the Northeast during the month of July when average precipitation is very low. More drought stress information
Leaves are yellow: Yellowing is veinal, may be associated with browning
Veinal yellowing or bleaching is caused by injury from Solicam (norflurazon) herbicide. More herbicide damage information.
Leaves are reddish-purple or maroon
- Seasonal temperature change (fall reddening)
- Phosphorus Deficiency.
Fall Reddening – Blueberry leaves develop a maroon color in autumn as a normal response to lowering temperatures. Less frequently, blueberry leaves may develop a reddish-purplish hue in spring if the weather is cold. This coloration disappears with the arrival of warmer weather.
Phosphorus deficiency causes purple coloration in blueberry leaves, but this is rarely observed in the field. Blueberries have a low P requirement. If the pH is too high (>5.2) for adequate P uptake, other nutrients likely will be unavailable as well. More nutrient deficiency information.
Leaves are red: Reddening is interveinal
- Magnesium deficiency
- Viral diseases – Blueberry Scorch and Sheep Pen Hill Disease.
Magnesium deficiency, common in acid soils, causes interveinal reddening because chlorophyll production is reduced. Symptoms begin as an interveinal yellowing and progress to a bright red. Leaves at the bases of young shoots are most likely to exhibit symptoms first. Young leaves at the tips of shoots are seldom affected. More nutrient deficiency information.
Viral diseases: A blueberry viral disease with similar symptoms is caused by two strains of the same virus. Blueberry scorch and Sheep Pen Hill disease (SPHD) are commonly found occurring on the West Coast and in New Jersey, respectively. Both are typically observed in spring when a blossom blight occurs. Blighted blossoms are retained through the summer but fail to develop into fruit. More blueberry virus information.
Leaves are red: Red spots are on the upper leaf surface only
Red ringspot virus causes spotting on the upper leaf surface only and on young shoots (below). More red ringspot virus information
Leaves are whitish
Powdery mildew: Powdery mildew can cover leaves with a whitish “film” more commonly seen on the undersides but occasionally on the tops as well. Most commonly, though, mildew expresses itself as red or brown spots on the upper leaf surface. More powdery mildew information.
Blueberry’s Yellow leaves
Thank you for your questions Tim.
First of all you say you believe you have acidified your soil (which blueberries do require), but you don’t say how you have done this nor how you are sure the soil has been acidified to the level that blueberries require. I think you should have a soil test done to at least to show you exactly what your pH level is. This may help you with a plan of action for these plants. Please see the link to the fact sheet on soil tests below. Additionally there is a link for a fact sheet on pH.
Yellowing leaves can be caused by a number of issues. Too much water can be one cause. We have had a lot of wet weather. When the new growth is appearing an over-abundance of water can cause the plant to have yellowing leaves.
Another cause for yellowing leaves is iron chlorosis. Yellowing occurs between the veins of the leaves, while the veins themselves remain green. Leaves may turn completely yellow and if the deficiency is severe enough will even turn reddish-brown in color. Our soils are rich in iron but often plants are not able to “pull” this iron from the soil and so they become iron deficient and exhibit signs of chlorosis. Sometimes, iron is more available to plants in soils that have a lower pH level which we would call soil that is more acidic. This is why blueberries are so difficult to grow here in Colorado, our soils are alkaline or have a high pH level. Since these two plants are of the same variety, this variety of blueberry may be even more susceptible to iron chlorosis. Chelated iron can be added to the soil to provide an iron product that is easier for the plant to absorb. It is important to know how much to add which a soil test will tell you. Please see the fact sheet link below.
One of the Extension Agents in Boulder County was growing blueberries in bales of peat moss without any soil at all. Peat moss can lower the pH level and is more acidic than our soils. He had good luck with this method.
The Arapahoe County Extension Office, 5804 S. Datura St. in Littleton has soil test kits available in the office. These kits are free and all the information and directions are included in the kits. The cost of the tests varies depending on the lab and what tests you want performed but this information is also available in the kits. The phone number is 303-730-1920 if you need further assistance.
Here is a fact sheet on soil tests:
Fact sheet on soil pH:
And on iron chlorosis:
Q: I have four blueberry bushes that are six years old. This year the leaves on two of the bushes are turning yellow but not falling off. Do they need more water or are they missing a mineral? I don’t want to lose any of them!
A: When leaves are yellow with green veins, the condition is called chlorosis. It is usually caused by a lack of iron in the leaves. There is plenty of iron in Georgia soil….so why is your blueberry not getting enough?
My guess is that the pH of your soil is too high. When soil pH is 4.8 to 5.5 iron is chemically able to be absorbed by the blueberry roots. As the pH approaches 6.0, iron becomes less and less available. Blueberries, like azaleas, thrive in acid soil but become chlorotic when the soil pH is above 6.0.
To know your exact soil pH you need to have a soil test done by your local Extension service (call 404-897-6261). If you don’t want to wait for the results, try sprinkling .5 pounds of sulfur per 100 square feet of area around your blueberries. Sulfur acidifies the soil, making iron more available. For a temporary solution, spray the foliage with iron-containing nutrient solution, such as Ironite(tm).
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Yellow Leaves on Blueberry Bushes
Blueberry image by Stana from Fotolia.com
You can plant and grow blueberry bushes in your garden, in a pot or as part of your landscaping. Not only will you be able to harvest fresh, tasty berries, but blueberry bushes are also attractive ornamental bushes. Blueberry bushes do, however, have specific requirements, both nutritional and environmental, for them to successfully grow and thrive.
Yellow leaves on your blueberry bush during the growing season signifies that something is wrong, either nutritionally or because of disease. The leaves of a plant are generally the first indication that there is a problem. Depending on the ailment, the yellowing will start in between the darker green veins of the leaf, or the leaf may develop yellow on the edge. Monitoring the foliage of your blueberry bush frequently for leaf color change will help you correct a serious problem before any significant damage is done to the plant.
When blueberry leaves, either tender new growth leaves or older interior leaves, begin to appear a lighter green or yellow green, it is a good indication your bush is suffering. The leaves will continue to lose the green color and turn yellow, most notably between the veins of a leaf, until the nutrition or environmental situation is corrected. There is one virus, the blueberry stunt, that will cause the leaves of a blueberry to yellow around the edge and between the veins, giving the leaf a mottled look.
The nutritional or environmental cause of lightening and yellowing of blueberry leaves is called chlorosis, which is the lack of chlorophyll in the plant. There are several factors that can cause chlorosis—compact or damaged roots, poor drainage or a high pH level in the soil which blocks the plant’s ability to take up the needed nutrients. The blueberry stunt virus is spread from plant to plant by the leafhopper pest.
The effect of chlorosis on blueberry shrubs if not detected and corrected soon enough is the bush will have premature leaf drop, and in extreme stress, may ultimately die. Certain nutritional deficiencies, like nitrogen and magnesium, will affect the older, interior leaves of the bush first, while a lack of iron will turn new grow yellow before affecting older leaves. Because the blueberry stunt virus easily spreads to neighboring plants, should one of your blueberry bushes be infected and not treated quickly, the virus will move and infect surrounding plants. Depending on the severity of infection, you may need to completely remove the infected blueberry bush from your garden.
To correct the situation and stop the leaves of your blueberry bush from turning yellow, determine the exact cause. This is done primarily through a process of elimination. Start by checking how well the soil is draining. Overly wet soil conditions can block the blueberry roots from being able to absorb the needed nutrients. The same is true if the soil is compacted, which will cause the roots to also be compacted and may be damaged. These conditions can be remedied by supplementing the soil around your blueberry bush with organic material. The organic material will open up the soil, allowing more air into it, which improves drainage and allows the roots to grow and expand more freely. Determining if mineral or nutrients need to be added, or if the pH level should be changed can best be determined with the assistance from your local agricultural extension office. Contact the local office to have your soil tested and recommendations as to what and the amounts of nutrients to add. To alleviate the blueberry stunt virus you must first eliminate the leafhoppers so no more plants are infected. Spray insecticide formulated to eliminate the pest on the infected blueberry bush and surrounding vegetation, then remove and destroy the infected blueberry plants.
Reasons For Blueberry Chlorosis – Tips On Blueberry Chlorosis Treatment
Chlorosis in blueberry plants occurs when a lack of iron prevents the leaves from producing chlorophyll. This nutritional deficiency is often the cause for yellow or discolored blueberry leaves, stunted growth, reduced yield, and in some cases, eventual death of the plant. Read on to learn what you can do about chlorosis in blueberry plants.
Reasons for Blueberry Chlorosis
What causes blueberry chlorosis? Most often, chlorosis in blueberry plants isn’t caused by a lack of iron in the soil, but because the iron isn’t available to the plant because the pH level is too high. In other words, the soil is too alkaline for healthy growth of blueberries. Alkaline soil is often present in areas where rainfall is low.
Blueberries require a low soil pH, and chlorosis occurs when a high pH level binds up the iron in the soil. Although the optimum pH level may vary somewhat between different cultivars, a pH above 5.5 is often cause for chlorosis in blueberry plants.
Blueberry Chlorosis Treatment
The first step in blueberry chlorosis treatment is a soil pH test. Your local cooperative extension office may provide tests, or you can purchase a testing kit relatively inexpensively at a garden center.
If leaves are looking puny, a foliar iron spray is a temporary fix that will get the plant through a rough patch while you are figuring out the next steps. Be sure the spray is marked “chelated” iron. Reapply the spray as new leaves appear.
A longer-term solution involves application of sulfur to lower soil pH, and this is where things can get complicated. For example, method and rate of application will vary considerably if your soil is loam, sand or clay.
There are a number of products on the market, including powdered sulfur, pelleted sulfur, elemental sulfur, lime sulfur, aluminum sulfate and others. The best sulfur for blueberry chlorosis treatment depends on soil pH, soil type, moisture, timing and other factors.
Your cooperative extension office will have plenty of fact sheets and other free information about blueberry chlorosis treatment in your area.
In the meantime, there are other steps you can take to improve the situation for your blueberry bushes. However, none should be considered substitutes for correction with sulfur products.
- Water regularly, especially during dry periods.
- Mulch well with bark chips, pine needles, oak leaves, or other acidic materials.
- Fertilize regularly using a high-acid fertilizer.