Plant Deficiencies: Why Are Leaves Turning Reddish Purple In Color


By: Susan Patterson, Master Gardener

Nutrient deficiencies in plants are hard to spot and are often misdiagnosed. Plant deficiencies are often encouraged by a number of factors including poor soil, insect damage, too much fertilizer, poor drainage or disease. When nutrients such as magnesium, calcium, potassium, phosphorus and nitrogen are lacking, plants respond in a variety of ways—oftentimes in the leaves.

Leaf problems in plants that are deficient in nutrients or trace minerals are common and may include stunted growth, drying and discoloration. Nutritional deficiencies present differently in plants, and a proper diagnosis is critical in order to rectify the problem. One of the most commonly asked questions relates to having a plant with purple leaves or leaves turning reddish purple in color.

Why Are Plant Leaves Turning Purple?

When you notice a plant with purple leaves rather than the normal green color, it is most likely due to a phosphorus deficiency. All plants need phosphorus (P) in order to create energy, sugars and nucleic acids.

Young plants are more likely to display signs of phosphorus deficiency than older plants. If the soil is cool early in the growing season, a phosphorus deficiency may develop in some plants.

The underside of marigold and tomato plant leaves will turn purple with too little phosphorus while other plants will be stunted or turn a dull dark-green color.

Leaves Turning Reddish Purple in Color

Leaves turning reddish purple in color is most often seen in corn crops. Corn with a phosphorus deficiency will have narrow, bluish green leaves that eventually turn reddish purple. This problem occurs early in the season, often due to cold and wet soil.

Corn suffering from a lack of magnesium may also display a yellow streaking between the veins of lower leaves that turn red with time.

Other Causes for a Plant with Purple Leaves

If you have a plant with purple leaves, it may also be due to elevated levels of anthocyanin, which is a purple colored pigment. This pigment builds up when a plant becomes stressed and normal plant functions are interrupted. This problem can be very hard to diagnose as other factors can cause the pigment buildup such as cool temperatures, disease and drought.

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Among the hardiest vegetable plants, cabbage can survive cold temperatures and even a bit of frost. Cold weather, though, may cause some cabbage leaves to turn purple. The discoloration isn't permanent and does not indicate a problem with the plants. The purple color should go away as the weather warms. Cabbage plants grow best when daytime temperatures are 40 to 80 degrees Fahrenheit. In order for cabbage transplants to produce the best heads, set them outside as soon as the ground can be worked in spring.

Cabbage plants' leaves may turn purple when the plants don't have enough nutrients. The deficiency is caused by a lack of fertilizer or poor soil, and, usually, the problem can be corrected by feeding the plants. If cabbage plants have a magnesium deficiency, their older leaves may turn purple, red or orange, and those discolored leaves turn brown and die over time. If cabbages have a nitrogen deficiency, their old leaves may turn purple, their young leaves may become pale green and the leaves may drop prematurely.


Comments (20)

Homertherat

I remember seeing that on some of the lettuce we grew last year in my Horticulture class. I don't know if we found out what it was, but I'm pretty sure we didn't even worry about it.

Shoofly22

do you have your lights on 24/7 that will cause it as will a shortage of phosphorous, i had the same problem about 6 weeks ago , i used a product that the nusery gave me called fertilome blooming and rooting soluable plant food
9-59-8 it had a high phosphorous number and the purple in my my plants gradually faded to yellow the a nice dark green . hope that helps you . or take your plant to the nearest nursery they are very helpful.
jim


Diseases

Although healthy purple passion plants generally resist disease, they are not immune. Diseases such as botrytis and fusarium wilt can cause the foliage to turn brown, wilt, curl and die. While these are generally more common on outdoor plants, pathogens can infect indoor purple passion plants via contaminated gardening tools or growing media or by handling the plants after touching infected plant material. Fungicides can help prevent or treat plant infections. The product label should list specific pathogens as well as provide clear instructions on how and when to apply the fungicide. Container-grown plants are easier to treat because you can take them out of the pot, wash off infected soil, dip the roots in fungicide and re-pot in a clean container with fresh, disease-free soil.


Cornell University

Leaves are:

Red or have red spots:

Purple or brown discoloration or spotting:

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. 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.

Nitrogen deficiency on ‘Bluecrop’ blueberry. Plant on the left did not receive adequate nitrogen fertilizer.

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.

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 from preemergent materials is usually accompanied by leaf yellowing or bleaching, followed by browning, and tends to be interveinal. More herbicide injury information.

Sinbar (terbacil) herbicide damage.

Princep (simazine) herbicide damage

Command (clomazone) herbicide injury.

Botrytis Stem and Leaf Blight – This fungus affects leaves and shoots during damp, cool springs

Mummy Berry Shoot Blight – Leaves become necrotic and are covered with powdery masses of gray spores during wet weather. 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.

Mummified blueberry and fruiting bodies of mummy berry fungus.

Potassium Deficiency – K deficiency results in marginal leaf burn. It is not common, but has been observed in very sandy soils.

Potassium deficiency in blueberry with characteristic marginal leaf burn.

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.

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

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.

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.

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.

Blueberry leaf scorch virus.

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.

Purple-brown spots on leaves and stems

Gloeosporeum leaf spot

Gloeosporium infection, caused by the fungi Gloeosporium minus and Gloeocercospora inconspicua, causes necrotic lesions on leaves and succulent stems.

Gloeosporium infection causes twig dieback and canker.

Gloeosporium fungus can cause symptoms on leaves and branches, as well as fruit.

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.

Purple-brown mottling may accompany crinkled leaves

Ringspot viruses, such as tomato rinspot and tobacco ringspot virus, are so named for the spotting and mottling that can arise on infected leaves. Occasionally, infected leaves may become crinkled without obvious discoloration. Before suspecting a virus, confirm that other causes of leaf discoloration are not to blame. Viruses can only be definitively confirmed with a lab test.
More ringspot virus information

Tobacco ringspot virus (necrotic ringspot) in ‘Patriot’ blueberry.

Leaves turn purple-brown at margins and are unusually narrow

Blueberry Shoestring Virus

Blueberry shoestring virus can cause straplike deformation in leaves accompanied by brown-purple discoloration. Before suspecting a virus, confirm that other causes of leaf discoloration and deformation are not to blame. Viruses can only be definitively confirmed with a lab test.

Blueberry Shoestring Virus.

Solutions

Use these resources if you need additional help with diagnosis and to find solutions to your problem.

Visit the Cornell Fruit Resources: Berries website


Why is this bad

At the point when your plants are lacking in phosphorus, this can general decrease the over all size of your plants. A lack of phosphorous causes moderate development and makes the plant end up plainly powerless, to little measure of Phosphorus causes moderate developments in leaves that might possibly drop off.

The edges all around the leaves or half of the leaves can be earthy and work its direction inwards causing the fan leaves to twist and become less effective in absorbing light.


Watch the video: Nutrient Deficiency in Pomegranate.


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