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Brown hydrangea leaves


5 Reasons For Hydrangea Leaves Turning Brown

IN THIS GUIDE

Walk through a British village or town and it’s almost guaranteed you’ll see hydrangeas, whether in a park, a churchyard, or standing proud at the boundary of somebody’s garden.

Their vibrant colour palette features bright pinks, moody blues, pure whites, and everything in between, making this bushy flower a firm favourite for our nation’s gardeners.

A long way from glory

What happens when those beautiful colours give way to brown, though? When things go awry, and your soft hydrangea petals begin to crisp up and wither?

Why Are My Hydrangea Leaves Turning Brown?

Firstly – remember that most hydrangeas will die back in Autumn, causing their leaves to turn brown and fall away.

New growth will be observed in early Spring, when you’ll notice green foliage sprouting from stems that might have appeared dead.

If your leaves are turning brown in Spring or Summer however, there’s likely other factors at play.

The precise reasons depend on the variety and their growing conditions, but in general, brown hydrangea leaves are a sign of dehydration and wilting in the heat.

1) They Got Too Hot

A dry hydrangea in Autumn

One sure-fire way to crisp up your hydrangea leaves is to give them too much exposure to the sun. In the spring when the mercury stays relatively low, they’ll do fine.

When things heat up over the summer however, time spent in the early afternoon rays can cause untold damage.

To avoid scorch damage: Grow your hydrangeas in a spot where they’ll get sunlight in the mornings and evenings, but not during the peak hours.

2) They Wilted Too Often

As well as being scorched, hydrangeas will brown if they’re left to wilt too often in the hot weather.

Wilting is caused by lack of moisture, meaning there are a few good tricks to use to prevent this from happening.

To avoid frequent wilting: Give your hydrangeas a healthy glug of water every few days when the temperatures are climbing high, and treat the soil to better retain moisture. A dab of mulch around the base of each plant should help with this.

3) The Leaves Got Wet!

While frequent water is paramount for hydrangeas in hot weather, watering too enthusiastically can cause problems.

When water settles on leaves and is unable to drain away properly, this can lead to browning. It can also lead to fungus and other issues that will damage the plant in other ways.

To avoid wet leaves: Take care when watering your hydrangea, making sure to water the soil and roots only rather than spraying all over the foliage as well.

4) You’ve Got Fungal Damage…

Another reason hydrangea leaves turn brown and wilt is fungal infection.

If this is the case you’ll see the telltale blemishes start to show up: brown pockmarks and a general appearance of bruising and damage to the leaf.

Fungal damage can cause browning but you may also see yellows and purples.

If you find leaf spot on your hydrangeas, fear not. It’s often possible to nip the problem in the bud, as it were, before the damage spreads to the whole point.

To avoid fungal damage: Prevention is the best cure when it comes to fungal damage.

First, take care to remove debris and dead plant material from beneath your hydrangea bush, as this will remove the breeding grounds used by fungi.

Second, trim the lower levels of your bush to allow air to circulate. This disrupts fungi spores from settling.

If you’ve missed the opportunity for prevention and are dealing with an infection you should remove all dead or severely infected leaves from the plant and destroy them to prevent further spread.

Keep an eye on leaves with light infection, and decide whether to use natural methods or fungicide products to keep the infection at bay.

5) They’re In Shock

Repotting hydrangea plants can be a bit of a shock to their system, and sometimes the shock is enough to cause hydrangea leaves to brown.

Dig deeper and this issue also ties back to moisture, and prevention is often a case of being a bit more careful when moving your plant.

To avoid repotting shock: Massage the roots of your plant when relocating to a new pot, then water generously as soon as it’s in the new soil.

This will give the roots of your plant adequate opportunity to absorb the moisture they need.

Should I Cut Off Brown Hydrangea Leaves?

The short answer is, “it depends.” While damage to leaves is unsightly, they can and will recover if you identify the problem and implement the solution early enough.

As a general rule of thumb, we recommend removing leaves when they are 50% brown or higher.

Often browning caused by moisture level issues or temperature can be reversed, and we’ve already mentioned that leaves with low-level fungal infection can often be saved with the right products.

If you’re vigilant and attentive to your hydrangeas it should be possible to keep them in good condition year-round.

Hydrangea Danger

While this article has shone a pretty bright spotlight on the various maladies that can befall the humble hydrangea, this plant is generally fairly easy to look after.

Take adequate steps to keep yours nicely watered over summer and out of direct sunlight in the peak sunshine hours, and you’ll be rewarded with a bountiful, colourful bloom.

Elizabeth Waddington

Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English & Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.Elizabeth is fully self-sustainable and grows her own forest garden on one-third acre of land which includes polyculture beds, a wildlife pond, mature fruit orchard and woodland. She has written various e-books on Permaculture and organic gardening, as well as designing gardens for hundreds of individuals, organisations and community gardens. She is also a full member of the Permaculture Association.

Hydrangea Turning Brown? (6 Solutions That Actually Work) – Gardener Report

Most often, the reason hydrangea leaves and flowers turn brown is because the leaves are losing more moisture then the roots can draw up. Excess wind saps moisture away from the leaves causing them to turn brown and curl up. Lack of moisture around the roots causes leaves and flowers to turn brown.

Most common reasons for hydrangea leaves and flowers turning brown:

Keep reading for why your hydrangea leaves and flowers are turning brown and how to implement the solutions to revive your hydrangea…

Hydrangea Leaves and Flowers Turning Brown and Wilting

Hydrangea leaves and flowers turning brown due to drought and too much sun scorching the leaves.

The reason for hydrangea leaves and flowers turning brown is because the hydrangea is loosing more water from the leaves then it can draw up at the roots. If the soil around the roots is not consistently moist the hydrangea leaves and flowers turn brown and wilt as a sign of stress.

Too much wind also saps so much moisture from the large surface area of the leaves that even if the soil is moist around the roots. the hydrangea leaves and flowers can still turn brown and curl up as the roots cannot draw up and replace the water loss quick enough from the leaves.

Hydrangeas require soil that retains lots of moisture around the roots.

If they are in dry, sandy or stony soils then water drains too quickly for the hydrangea’s roots to draw up the moisture it needs, which can be the cause of your hydrangea leaves turning brown and wilting.

There is no universal specific guide on watering for hydrangeas as it depends on climate, weather and factors such as the maturity of the hydrangea plant but hydrangeas should be watered (with a thorough watering) as often as required so that the soil is moist.

At the hottest times of the year it may be necessary to water your hydrangea nearly every day (especially if it is in a pot).

The Solution…

To revive hydrangeas with brown leaves and flowers it is necessary to recreate the conditions of the hydrangea’s native environment by planting hydrangeas in moisture retains soil, watering the hydrangea as often as required to keep the soil moist and sheltering the hydrangea from wind which saps moisture.

You can either cut back any brown leaves and flowers with pruners at any time of year or wait for them to fall naturally.

Although it is important emphasize that a light pruning is best and to caution against any heavy pruning as this can remove the growth from which the flowers are displayed.

I should also emphasize the importance of regular watering and the use of mulch.

Hydrangea naturally have a mulch of fallen leaves on the wood land floor every year which helps conserve moisture so adding a layer of leaf mold or compost can really help to emulate the moisture retentive soils to which hydrangeas are adapted.

Once the hydrangea is growing in its preferred conditions the leaves should stay green, although the flowers usually do not revive and you may have to wait until they bloom the following year.

(Read my article, how to revive a wilting hydrangea).

Potted Hydrangea Leaves and Flowers Turning Brown

The reason for potted hydrangea leaves turning brown are largely the same as why any hydrangea turns brown.

However there are a few characteristics pertaining specifically to growing hydrangeas in pots that can increase the risk of brown leaves and flowers.

Potted hydrangea leaves turn brown most often because they are planted in pots that are too small and dry out too quickly. Hydrangea have extensive root systems and a high demand for moisture in the soil. If the soil dries out then the leaves wilt or curl up and turn brown as a sign of stress.

If the pot is too small then it has less capacity for potting soil which retains moisture.

Whenever I see a hydrangea with brown leaves in a pot, I always check the roots as the are usually pot bound and therefore have less access to moisture.

It should be noted that pots also require watering far more often then hydrangea planted in the garden as pots can dry out very quickly on hot days and result in a dying hydrangea.

The Solution…

With a larger pot and more frequent watering, the hydrangea should have all the resources it require so that the leaves stay a healthy green rather then turn brown.

Ensure that the pot is in a sheltered area, out of the wind, and in dappled light or morning sun followed by afternoon shade.

Clip back any brown leaves or flowers at anytime or you can leave them for the hydrangea to shed naturally.

Too Much Sun Scorches Hydrangea Leaves and Flowers Brown

Hydrangea leaves and flowers turn brown and scorched if they are in too much sun. Hydrangeas are adapted to living under a tree canopy with dappled light throughout the day and do not tolerate being in full sun which not only scorches the leaves brown but can contribute to drought stress.

Hydrangeas are woodland plants that thrive under trees which protects them from excess wind, sun and frost damage in Winter.

Whilst hydrangeas can grow in full shade, they tend to grow green foliage but with fewer flowers.

They key to growing hydrangeas, (ensuring a good display of flowers and avoid scorching the leaves brown) is to find the optimal balance of sun in your garden.

Typically hydrangeas grow best when in an area of morning sun followed by afternoon shade or in dappled light throughout the day.

This balance of sunlight and shade ensures they hydrangeas has enough energy to produces flowers yet is protected enough from intense sun and heat to prevent the leaves and flowers turning brown and wilting.

The Solution…

To create the optimal balance of sun and shade and avoid the leaves turning brown, you can transplant your hydrangea under a tree to replicate its natural conditions of dappled light or attempt to shade it with some taller plants such as bamboo.

Or you can find a shadier area of the garden. The goal should be to ensure that the hydrangea is shaded during mid day and afternoon when the sun as at its most intense and temperatures are at their highest.

Not only will this prevent the leaves scorching brown but also mitigate drought stress at the hottest times of the day.

Trim back any brown leaves and flowers or wait for the hydrangea to shed them naturally.

Hydrangea Leaves Turning Brown on the Edges (Fertilizer Burn)

If your hydrangea leaves are brown at the edges this is often because of fertilizer burn from using fertilizer too often or in too high concentration. Hydrangeas require a slow release fertilizer as an abundance of nitrogen causes the leaves edges to turn brown as a sign of stress.

Hydrangeas are relatively heavy feeders that grow best in fertile soil and benefit from the use of a fertilizer in the Spring to support healthy growth and display more flowers.

However hydrangeas are very sensitive to over use of fertilizer causing their leaf edges to turn brown and crispy and it can reduce the display of flowers.

This often happens due to lawn fertilizer diluting in heavy rainfall, which then runs off into garden boarders where your hydrangeas is planted.

More is not better when it comes to fertilizer as slightly too much fertilizer can promote foliage growth at the expense of flowers and applied too much or too often results in leaves with brown edges and cause the hydrangea to droop.

The Solution…

The key is find the right kind of fertilizer for hydrangeas.

Personally I recommend miracle-gro all purpose granular fertilizer which contains all the nutrients the hydrangea requires for growth and flower at the right concentration to avoid the leaf edges turning brown.

The granulated formula releases the nutrients slowly to mitigate any risk of fertilizer burn.

A slow release granular fertilizer contains all the nutrients a hydrangea requires at the right concentration to support flowers and prevent the leaf edges turning brown.

(Read my article, why isn’t my hydrangea flowering?)

Cold Weather (Hydrangea Buds and New Growth Turning Brown)

The new leaves and flower buds of hydrangeas turn brown if they are exposed to a late Spring frost or cold Winds. The newly emerging buds and leaves are particularly tender and especially vulnerable to damage from a sudden cold snap, causing the buds to turn brown and die back.

Hydrangeas naturally grow in sheltered areas under trees which buffer and harsh cold winds and creates a more stable micro-climate in which the new flowers can emerge without such a significant threat of frost.

When the new buds and leaves of hydrangeas become frost damaged, the leaves turn brown and the buds can turn to a mushy texture.

It is usually the outer most growth that is most badly affected as it is more exposed to the elements.

Unfortunately the damaged flower buds are not then able to flower and the newly emerging growth most likely will not recover.

The Solution…

Frost damage to hydrangea flower buds and leaves is more prevalent where the hydrangea is more exposed, so plant or transplant your hydrangea to a more shelter part of the garden, by your house or near some other plants and hedges.

Hedgerows in particular are excellent at buffering wind as they provide a wall of protection for your hydrangea and can also help to mitigate the affects of frost.

However once the flower buds and newer leaves have turn brown there is not much you can do to revive them. Therefore cut back any growth that has been damaged by the frost and trim back to healthy growth.

Hydrangeas often have developing flower buds further down each branch which is naturally more protected the the flower buds on the outermost part of the plant and they usually survive a frost.

This means your hydrangea can still flower, although it may be much later and with fewer flowers emerging, so with some patience there should still be some good blooms on display in the Summer.

(Read my article, how to revive a dying hydrangea).

Flowers and Leaves Turning Brown From Overhead Watering

Hydrangea flowers and leaves can turn brown from excessive overhead watering which can damage the delicate flowers and promote the conditions for leaf spot fungus which appears as small brown spots on the hydrangea leaves and can cause the to drop off.

When watering hydrangeas, always water at the base of the plant rather then onto the foliage and flowers. Hydrangeas are hardy enough to tolerate some water on their leaves from rainfall but excessive watering onto the leaves in the Summer is usually what promotes the conditions for leaf spot fungus to spread.

Leaf spot is a fungal disease that does not kill the hydrangea but the stress of the disease can reduce its overall growth and reduce the number of flowers on display.

Eventually the leaves can fall off and its important to clear them up and burn or dispose of them to try to limit the spread of the fungus.

Watering at the base of the hydrangea is an effective way of mitigating the affects of leaf spot fungus and prevents it spreading to other parts of the plant.

The best way to robustly solve the problem as it usually comes back every year, if it is left untreated is to use a fungicide spray and leaves with several applications usually around 14 days in between, although you should always follow the manufacturers in instructions.

(Read my article, why are my hydrangea flowers turning green?)

Key Takeaways:

why the leaves of the flower turn brown, dark, black and yellow spots appeared, methods of treatment and treatment

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Spots on hydrangea leaves: causes and their treatment Brown spots on leaves

  • Dark spots on leaves with white and gray rot
    • nine0011 White rot
  • Gray mold
  • Dry and wet black spots on leaves
  • Yellow spots on leaves
    • nine0019 Rust on hydrangea
  • Hydrangea ring spot

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    45 likes

    Lush and beautifully blooming hydrangea can be an ideal option for decorating a garden or garden plot. It takes a lot of effort to grow it. And one of the main concerns will be the fight against diseases. Although the plant is resistant to various ailments, it will be necessary to spray in a timely manner. Chemical preparations will help to eliminate the symptoms and the diseases themselves in a short time. nine0003

    Show

    Brown leaf spot

    Sometimes you can see that the hydrangea leaf is covered with a brown spot. nine0069 This is a symptom of one of the most common diseases called septoria. Initially, a small round shaped affected area will appear on the leaves. The diameter of the spots is usually 2–6 mm. Gradually, the spots expand and cover the entire surface. The brown leaf gradually dies and falls off. Without timely assistance, the plant may die completely. If you do not carry out treatment, then spotting will affect the stem itself. Spraying should be done immediately after the first signs of septoria are detected. nine0003

    To save the flower, it is necessary to remove the affected foliage and shoot. They are burned to prevent the spread of infection throughout the garden. The cut point must be treated with a special solution called copper sulfate. They are also recommended to spray healthy branches for preventive purposes. Spotting can also be treated with other preparations containing copper, such as copper oxychloride or Bordeaux mixture.

    Important! Different types of hydrangeas are more or less susceptible to certain diseases. For example, the arborescens more often have burns, and the petiole is resistant to any ailments. nine0082

    Other chemicals are also allowed:

    • "Topaz";
    • Falcon;
    • Ridomil Gold;
    • Profit.

    Another reason for the appearance of brown spots is an excess of sunlight and the lack of sufficient moisture in the soil for the plant. For irrigation, it is recommended to use only soft water collected after rain. To get rid of such manifestations on the leaves, it is necessary to transplant or shade the plant by planting higher crops. If these measures are taken in a timely manner, the spots will gradually disappear, and the hydrangea will return to its former beautiful appearance. nine0003

    Dark spots on leaves due to white and gray rot

    A dark coating that gradually becomes mottled forms on hydrangea leaves due to a fungal infection. Such ailments usually begin in the root system, resulting in a decrease in nutrients in the plant itself. The infection enters the soil along with garbage or passes from neighboring crops. Outdoors, gray and white rot are rare. Plants that are grown in greenhouses and greenhouses are more likely to be infected. nine0003

    Find out also why the hydrangea blooms green.

    White rot

    The symptoms of this disease are:

    1. Browning on shoots.
    2. Rotting of stems at the base.
    3. White coating on leaves.

    If timely measures to eliminate the disease are not taken, then a gray coating first begins to appear on the leaves. When a white coating forms on the shoots, they can no longer be saved. We'll have to immediately dig up the plant and burn it. Otherwise, the disease can spread to neighboring crops. nine0003

    Important! Rot due to fungal attack can only be cured at the initial stage of infection.

    It is necessary to treat the disease in several steps. First, all infected shoots are removed. Then sprayed with fungicides. The cut points must be treated with a weak solution of potassium permanganate. As chemicals, experienced gardeners recommend using mixtures that include copper. It can be common copper sulfate or Bordeaux liquid. nine0003

    Gray mold

    Hydrangea young shoots and leaves are at risk. The main reason for the appearance is considered to be an excess of moisture in the ground. This happens due to excessive watering or a dense, not thinned crown. It is the increased level of humidity that leads to the spread of fungal infections. The main symptom by which gray rot can be identified is a soft coating. Upon contact with an infected leaf area, characteristic dark spots appear. Over time, they completely dry out, turning the surface into dust. nine0003

    It may be useful for you to know why the hydrangea paniculata does not bloom.

    The disease is treated in the following way:

    1. After removing damaged shoots and leaves, the cut points are treated with a weak solution of potassium permanganate. If the stage of infection is too late, then the hydrangea is best dug up and burned to avoid infection of neighboring plants.
    2. A diseased plant is sprayed with chemicals. It can be a 1% solution of Bordeaux liquid or "Fundazol". nine0008

    Gray mold is just as contagious as white mold. If it is not eliminated in a timely manner, then other crops in the garden may suffer.

    One of the reasons for the formation of dark spots on the leaves is downy mildew. This fungus appears as a result of temperature changes in the environment. Especially dangerous is the period when warm, humid weather with a temperature of + 18 ... + 20 ° С is kept. Fat spots appear on the foliage. With the development of the disease, they begin to darken. To eliminate this fungus, a solution based on 150 g of soap, 10 liters of water and 15 g of copper sulfate is used. nine0003

    Dry and wet black spots on leaves

    Hydrangea has black leaves due to a combination of negative factors. Flower growers divide this manifestation into dry and wet blackening. In the first case, brown spots are observed on the leaves of the bush. If timely measures are not taken, the plant will gradually dry out and may disappear. The main reason why the disease begins to form is too hard water used for irrigation. To avoid this situation, the liquid is settled for at least 24 hours in a container. Also, such formations can appear due to excessive direct sunlight. Burns can be avoided by planting the hydrangea under the cover of other plants or under buildings. nine0003

    Read also what to do if there are brown spots on hydrangea flowers.

    Wet black leaf is characterized by wilting and subsequent darkening. The reasons for its appearance are:

    • sudden changes in temperature or drafts;
    • too frequent watering with subsequent stagnation of water on the surface of the earth under the bush;
    • heavy soil that does not allow moisture to pass through and does not allow the roots to receive the necessary oxygen.

    To prevent wet blackening from spreading throughout the site, it is recommended to water in accordance with the recommendations of flower growers. If the season turned out to be rainy, then the plant should be given less water. You should not plant a shrub in a place that is constantly under sunlight or in drafts. Heavy soil must be constantly loosened and only then watered.

    Yellow spots on leaves

    The yellowness of the leaves may appear not only due to an infectious disease. Many novice gardeners do not even suspect that the problem may lie in poorly selected seedlings, so when buying a hydrangea, you should carefully examine the plant. The best option would be to purchase only from trusted suppliers. nine0003

    But even an uninfected seedling can turn yellow. The reason for this phenomenon lies in improper care, due to which a disease called chlorosis is formed. The plant has a metabolic disorder. The initially yellowing leaf becomes dark and dry over time. First, yellow appears, then crimson in neoplasms. Over time, it turns brown. The sheet dries up completely.

    Among the main causes of chlorosis:

    1. Moisture accumulated excessively on the ground. Although hydrangea loves moist soil, it should not be over-watered. Accumulated water at the roots leads to the formation of rot and other fungal infections.
    2. Lack of normal soil acidity. If the soil is too alkaline, then the hydrangea will not be able to grow and develop normally. To avoid this situation, it is recommended to add a little citric acid to the water for irrigation.
    3. Direct sunlight. Like most crops, the flower does not tolerate excess ultraviolet radiation, so for planting, you should choose the most suitable place in the garden where partial shade will reign. nine0008
    4. Lack of mineral fertilizers. Yellowness and spots on the leaves of the plant may appear due to lack of top dressing.
    5. Too much organic fertilizer and lime. Experienced flower growers recommend using these substances within the normal range, avoiding their excessive use.

    The method of dealing with such a phenomenon as yellow spots or chlorosis is very simple. It is enough to adhere to the optimal and established norms, to perform proper care. It is recommended to regularly apply a small amount of iron-containing chemicals as a top dressing. nine0003

    The normal pH level for hydrangeas is 4-6. To determine it, use litmus paper. If it is placed in a humid environment, then in the absence of acidity, it will turn yellow. When its shade acquires a green or green-blue color, this means that the soil has a normal pH level.

    Treatment with preparations containing iron will help to remove yellowness from the leaves. In the domestic market, these are Ferovit and Antichlorosis preparations. To increase the acidity of the soil, you can prepare a special solution for watering or spraying at home. To do this, it is necessary to dissolve 4 g of citric acid and 3 g of ferrous sulfate in one liter of water. nine0003

    We recommend to find out why the hydrangea does not bloom.

    Spots can be not only yellow, but also green in the formation of a disease such as powdery mildew. A characteristic feature of this disease is the formation of a gray coating under the foliage. Over time, the shoots curl up and die. Hydrangea may disappear completely. To cure it, it is recommended to use one of the modern drugs: Fitosporin-B, Topaz, Skor.

    Hydrangea rust

    A rusty or red coating on hydrangea leaves, which eventually causes them to wither, is most often due to a fungal infection. The reason for its formation is an excess of water and the absence of nitrogen supplements. The main symptom is the initial yellowness on the leaves. Subsequently, it turns into a rich burgundy color. Over time, the leaves begin to turn brown and rust, dry spots appear in these places, causing them to fall off. nine0003 In these neoplasms, a specific plaque is often formed, which, upon contact with it, turns into dust. It is she who is the spores of a fungus that parasitizes on a plant. They easily fly around from the leaves, thereby being picked up by gusts of wind and infecting other crops.

    Hydrangea rust is treated using several proven and effective methods:

    • removal of infected shoots;
    • treatment with chemicals.

    Domestic fungicides are often used as the latter. It can be "Topaz" or "Falcon".

    Hydrangea ring spot

    Ring spot, which appears on hydrangea foliage, is one of the most common diseases of this crop. Initially, it manifests itself in the form of irregularly shaped rings. Their diameter usually does not exceed 2 cm.

    Since there are a large number of them, the leaf begins to change its shape. nine0070 Over time, it completely shrinks and dies. One of the most dangerous symptoms is damage to the buds. They either disappear altogether or decrease in size. The flowers will be small and sluggish.

    Unfortunately, at the moment there is no cure for this disease. The only preventive measure is the choice of healthy seedlings. This disease spreads through seedlings. If the breeding method is used by dividing the bush, then the mother bush must be completely healthy. nine0003

    All the above types of spots sometimes cause irreparable harm to the plant. That is why it is important to follow all the rules for the care, planting and transplanting of hydrangeas. Only a timely response to diseases, spraying with chemicals and prevention will help keep the shrub beautiful and flourishing.

    Tags: Ornamental shrubs

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    Hydrangea diseases: description, photo, treatment

    Hydrangeas are strong and beautiful plants, but many problems can arise in the process of growing them. One of these problems is various diseases. Unfortunately, hydrangeas have a wide list of threats that can harm them. nine0003

    The most common fungal diseases affecting mainly leaves. The next threat is bacteria, which is a serious problem for gardeners. Another nasty enemy is viruses. This is a separate group of microorganisms with which it is useless to fight. And finally, the disease is caused by anatomical changes or a lack of trace elements in the soil.

    nine0281 Treatment nine0281 It is impossible to cure, buy healthy plants, remove infected ones.
    Disease name (pathogen) Symptoms
    Cercospora Hydrangeae brown dots Remove infected leaves, spray with fungicide.
    Anthracnose (Colletotrichum gloeosporioides, Colletotrichum dematium) Red-brown spots Prophylactic spraying with fungicides.
    Gray mold (Botryotinia fuckeliana) Black spots in gray mold in the center Avoid planting in too shaded areas, use biological fungicides.
    Powdery mildew (Erysiphe friesii var. friesii) White coating Neem oil, fungicides.
    Rust (Pucciniastrum Hydrangaeae) Red spots Remove diseased leaves, spray with fungicide.
    Verticillium wilt (Verticillium dahliae, V. albo-atrum) Leaves turn yellow and wither Remove affected leaves and twigs, use high phosphorus fertilizer.
    Bacterial wilt (Ralstonia solanacearum) Leaves wither Buy healthy plants, use clean soil.
    Bacterial leaf spot (Xanthomonas campestris) Small spots on leaves that exude moisture
    Hydrangea ringspot virus (HRSV) Yellow circles Plant only healthy hydrangeas, remove infected ones.
    Hydrangea mosaic virus (HydMV) Yellow patterns Cuttings should only be taken from healthy plants.
    Impatiens Necrotic Spot Virus (INSV) Leaf circles Kill disease vectors.
    Chlorosis Leaves turn yellow Add iron to the soil, create drainage.
    Virescence Flowers turn green Spray with all disease preventatives.

    Fungal diseases

    Powdery mildew (Golovinomyces orontii)

    A common disease affecting the large-leaved hydrangea (H. macrophylla) in greenhouses, nurseries and in warm and humid conditions. The disease also affects H. serrata, H. arborescens, H. macrophylla, and H. paniculata.

    Symptoms. Early signs of powdery mildew on hydrangeas are round, light gray spots of mycelium and spores on both sides of the leaf surface. Pustules of fungal tissue will eventually turn into yellow or purple spots on the leaf. As the disease progresses, the fungus develops on the surface of the leaves, occupying a vast area. On heavily infested plants, premature leaf drop may occur. Plant growth may suffer due to reduced active leaf area and shoot elongation directly reducing photosynthesis. Powdery mildew is rarely fatal to plants in landscape conditions. The main damage is a decrease in the aesthetic qualities and viability of plants. nine0003

    Biology and epidemiology. Hydrangea macrophylla powdery mildew is caused by G. orontii (formerly Erysiphe polygoni) AND Erysiphe poeltii. Powdery mildew caused by Oidium hortensiae (Hydrangea powdery mildew) on H. macrophylla was first reported in Korea in 2012. The causative agent is an obligate parasitic fungus that inhabits the leaf surface of the plant. Dry conditions, high humidity, and warm day/cool night temperatures favor the disease. The pathogen receives its nourishment from epidermal cells infected with root-like structures called haustoria. The fungus overwinters as hyphae or spores in the buds of previously infected plants in the landscape and living plants in greenhouses. nine0003

    Treatment

    Prevention. Propagation should be done from cuttings of healthy plants. Lower the relative humidity in the greenhouse and increase the distance between plants to improve air circulation will suppress powdery mildew. Placing plants in sunny locations and avoiding rain watering will help reduce the incidence. Growers should remove infected plants and debris from previous crops to reduce the source of infection.

    Chemicals. Fungicides are available for controlling hydrangea powdery mildew. Applications should be started when the initial symptoms of the disease are observed or conditions are favorable for the development of the disease. Fungicide applications should be repeated at 7-14 day intervals or as directed on the label. Some fungicides include azoxystrobin, fenarimol, paraffin oil, and thiophanate-methyl. Crop rotation with fungicides should be practiced to minimize the development of fungicide resistance. Fungicides from different fungicide groups (FRAC groups) should be used, which act using different mechanisms of action. nine0003

    Biorational preparations. The use of biorational products is also effective in controlling powdery mildew. However, when the first symptoms of powdery mildew appear, the drugs should be used prophylactically. Thorough coverage of the upper and lower sides of the leaves is recommended. Sodium bicarbonate (baking soda), sold as Armicarb™ (potassium bicarbonate (MilStop)), and fatty acids from Neem seed oil, are designed to control powdery mildew.

    Biocontrol. nine0070 Bacillus subtilis QST 713 is noted as a biological control agent for powdery mildew in hydrangea.

    Resistant varieties. Varieties belonging to H. serrata are more resistant than H. macrophylla. Of the 90 H. macrophylla cultivars that were evaluated for powdery mildew resistance over a 3-year period, three cultivars, 'Amagi Amacha', 'Shirofuji' and 'Veitchii', were ranked among the most powdery mildew resistant cultivars each year. The cultivars, 'Diadem', 'Komachi' and 'Omacha', were highly resistant in 2006 and 2008, and moderately resistant in 2007. Large-leaved hydrangea 'Veitchii' showed higher resistance to powdery mildew in in vitro tests. nine0003

    Cercospora hydrangea (Cercospora hydrangea)

    The disease usually affects large-leaved and tree-like hydrangea, also oak-leaved hydrangea. The disease is especially true in warmer regions. Hydrangea cercosporus, which causes leaf spot, almost never kills the plant, but can cause significant premature leaf drop, reduced plant viability and flower bud set.

    Symptoms. nine0070 Symptoms of leaf spot vary depending on the type of infected hydrangea. Older leaves at the bottom of the plant usually show the first visible symptoms, then spread upward towards the top of the plant. Initially, the leaf spots are purple and small, round in shape, then the spots increase, become angular or irregular in shape and acquire a yellow-brown or gray center surrounded by a purple or brown border. Hydrangea oakleaf leaf spots are angular, dark brown to purple and may turn yellow-green. nine0069 Leaf spot often begins in mid-summer and becomes noticeable by early autumn.

    Biology and epidemiology. The main source of the disease are hydrangea cercosporosis conidia overwintering in leaf debris. The spores are spread to the healthy underside of the foliage through heavy rain or ground watering, also by wind. Periodic summer heavy rains can greatly accelerate the spread of diseases, increase levels of spotting and defoliation (leaf fall). On the other hand, suppression of the development and spread of the disease can be prolonged by periods of drought and prolonged exposure to the sun. nine0003

    Treatment

    Prevention. Applying enough nitrogen will help ensure good plant growth. Drip irrigation or the use of irrigation hoses and wide spacing between plants to allow air movement and reduce leaf moisture have been reported to reduce the incidence of cercosporosis on leaves. The correct choice of location is a must. The use of well-drained sites and partial shade with direct exposure to morning sunlight promotes better hydrangea growth and reduces leaf disease. nine0070 A good sanitation strategy requires the removal and destruction of diseased leaf debris that serves as a source of infection for new plants.

    Chemicals. The use of protective fungicides is recommended for valuable landscape plants that show noticeable damage annually. Fungicide treatment should be started at the first symptoms of leaf spot and continued as needed. Preparations containing chlorothalonil, myclobutanil, or thiophanate-methyl are very effective when used early in the disease. nine0070 Prophylactic use of chlorthalonil or mancozeb has been found to significantly reduce the severity of Hydrangea large-leaved cercosporosis. The use of protective fungicides is recommended for plants that show noticeable damage annually.

    Gray rot, or Botrytis cinerea

    Botrytis, or gray rot, is a serious problem in the cultivation of flower crops. Gray mold (Botrytis cinerea) has a wide range of hosts, including many annual and perennial herbaceous plants. The fungus is considered an opportunistic pathogen that infects weakened or damaged leaves and flowers, especially in cloudy, wet and rainy weather. nine0069 All types of hydrangea are susceptible to this disease, but large-leaved hydrangea is the most susceptible .

    Symptoms. When flowers are infected, the first symptoms are watery spots on the petals, which form reddish-brown spots of irregular shape, which can eventually cover the entire flower. Affected flowers quickly turn brown and dry. An indistinct gray growth (spores and conidiophores of a fungal pathogen), a characteristic symptom of gray mold, is usually seen on affected flowers under humid or very humid environmental conditions. Leaves can become infected when diseased petals or other infected debris fall on them, and brown, irregularly shaped necrotic lesions appear on the leaves. nine0003

    Biology and epidemiology. Gray mold can survive in plant debris as a saprophyte or pathogen on a wide range of host plants. The fungus also overwinters as black dormant structures (sclerotia) on dead plant tissue or in the soil. The pathogen can be transmitted by wind, water spray, insects, and human activity from affected plants. Spore germination requires high relative humidity or water films on plant surfaces. Gray mold infestation requires a 5-8 hour wet period. Germinated spores penetrate directly into healthy flowers and leaves, and also penetrate through natural openings and wounds. nine0069 Favorable conditions for the development of the disease are unbalanced nutrition, low light intensity, cool temperature and high humidity, especially in conditions of several days in a row in cloudy, humid, rainy weather. The optimum temperature for botrytis infection to occur in a greenhouse is approximately 15 °C. All types of hydrangea are susceptible to gray rot, but most often the lesion is observed on large-leaved hydrangea.

    Treatment

    Prevention. Ventilation and simultaneous heating of greenhouses at night can remove moisture. Avoiding watering from above will help keep the canopy dry and lower the relative humidity, which can quell the disease. It will also help to increase the distance between plants and trim loose leaves from the underside of plants to improve air circulation and encourage rapid evaporation of moisture from plants and soil surfaces, avoiding leaf or shoot wounds that can further spread the disease. It is recommended to water the plants in the morning to ensure the rapid evaporation of excess moisture from the surface of the plants. nine0003

    Sanitation. Proper sanitation is critical to the control of gray mold. But sanitary measures should not be carried out if the plants are wet from dew or rain, because they will spread fungal spores in the air. In the fight against the disease, removing infected leaves and damaged flower heads from plants and destroying them to reduce microbes in greenhouses helps.

    Fungicides. Plant protection against infection is easily managed with fungicides. The first application of the fungicide should be done in the spring when consistently cool and wet weather is expected or when there has been a problem with gray mold in the past year. The choice of fungicides depends on the location and type of plants being treated. Some recommended effective fungicides include iprodione, mancozeb, and thiophanate-methyl . To prevent the development of fungicide resistance, always alternate fungicide applications between chemicals with different mechanisms of action. Resistance to thiophanate methyl and iprodione has been reported.

    Biological. Some biofungicides, such as Mycostop (Streptomyces griseoviridis strain K61), actinate (Streptomyces lydicus), are effective against gray mold.

    Resistant varieties. The use of resistant varieties is most effective, however, no major Botrytis resistance gene has been identified in hydrangeas.

    Rust (Pucciniastrum hydrangea)

    In nurseries and gardens, hydrangea rust is more common on Hydrangea arborescens. The pathogen can affect hemlock, but is more common on hydrangeas.

    Symptoms. Hydrangea leaves show symptoms as small yellow or orange spots which then develop into necrotic angular lesions as fungal growth is usually restricted to large veins. Orange dust (urediniospores) forms on the underside of infected leaves when the fungal bodies (uredinia) mature. As the disease progresses, symptoms become noticeable throughout the plant. nine0003

    Biology and epidemiology. The hydrangea rust fungus requires two genetically distinct hosts, hemlock and hydrangea, to complete its life cycle, including Tsuga canadensis (oriental hemlock), Tsuga caroliniana (caroline hemlock), H. arborescens (tree hydrangea) and H. paniculata (paniculata hydrangea) . Urediniospores produced on hydrangea leaves repeat several cycles of hydrangea infection during the season. Flat, reddish-brown telia develop inside epidermal cells on both sides of the hydrangea's leaf surface in late summer and autumn. Teliospores germinate and produce basidiospores, which infect hemlock leaves in spring. In late spring - early summer, on the lower surface of the hemlock leaves, cylindrical aetsia of a light cream color are formed. When the aetia mature, orange-yellow aeciospores are released, which infect hydrangea leaves in spring. nine0003

    Treatment

    Prevention. Reducing the relative humidity and the duration of wetting of plant tissues are critical for disease control.

    Fungicides. Chlorothalonil 720 SC and Daconil Weatherstik are designed to control hydrangea rust. The first fungicide application should be made in the spring to protect the leaves. Doses and re-applications of fungicides should be as recommended on the label.

    Resistant varieties. Significant differences in hydrangea rust resistance have been reported among Hydrangea arborescens cultivars. Among the seven cultivars tested, 'Frosty' was highly resistant, 'Green Dragon' was highly susceptible, and the other five cultivars, 'Ryan Gainey', 'Pink Pincushion', 'White Dome', 'Mayes Starbust' and 'Annabelle,' were intermediate.

    Hydrangea anthracnose (Colletotrichum gloeosporioides)

    Hydrangea anthracnose is caused by the fungus Colletotrichum gloeosporioides and is periodically found in landscape and field plantings of landscape and field hydrangeas. Anthracnose affects the leaves and flowers of hydrangea. nine0003

    Symptoms. Hydrangea leaves initially develop round or slightly irregular brown spots , the center of which reaches 2.5 cm or more in diameter and becomes light brown to brown in color. Subsequently, alternating dark and slightly lighter rings of dead tissue appear, forming a "bull's-eye" or "target spot" appearance. Large, irregularly shaped, dark brown spots may spread over the petals and leaves of flowers when environmental conditions are favorable for the development of the disease. nine0003

    Biology and epidemiology. Anthracnose has a wide host range among woody shrubs and trees. The causative agent hibernates in the affected fallen leaves of hydrangea and other plant debris. The disease is favored by hot, humid weather. Masses of spores ooze from fruiting bodies (acervuli) covered with leaf debris. With constant leaf moisture, the spores spread to other leaves and flower petals by splashing water. The pathogen is able to quickly penetrate into host tissues and colonize them at high temperatures of 24-32 °C. The rate of infection of the disease and the appearance of symptoms are increased due to prolonged periods of heavy fog, frequent rainfall and dew. nine0069 Hydrangeas that are heavily fertilized may be more susceptible to anthracnose infestation.

    Treatment

    Prevention. The use of disease/symptom free plant clippings can greatly reduce the chance of spreading the disease. Removing and destroying diseased leaf debris or diseased flowers eliminates and reduces the spread of anthracnose .

    Chemicals. The use of protective fungicides is a viable way to protect susceptible hydrangeas from anthracnose. Application should be carried out at 10-14 day intervals during the summer to achieve good efficacy. Some of the recommended fungicides include chlorothalonil and thiophanate-methyl, and should be used according to the manufacturer's instructions. nine0003

    Target spot (Corynespora cassiicola)

    The disease affects the leaves, stems and petals of flowers and causes irregularly shaped brown necrotic lesions. The disease can spread rapidly in hot and humid weather and can lead to the death of small plants and a serious reduction in the aesthetic value of plants.

    Symptoms. Symptoms of the disease appear as brown spots of various sizes on hydrangea leaves, which are similar to spots caused by cercosporosis. Target spot is favored by a similar environment that is described for cercosporosis and is often isolated as part of a disease complex. nine0003

    Biology and epidemiology. Target spot has been found on over 300 plant species. The pathogen survives in infected plant debris and on the stems of previously infected plants.

    Treatment

    Prevention. Removal and destruction of diseased leaf debris that serve as a source of infection for new plants. Avoid rainfall and crowding of plants.

    Chemicals. Cercospora and Corynespora leaf spot diseases tend to have annual outbreaks when the pathogens have established themselves in an area. Protective fungicides are recommended for valuable landscape plants that show noticeable damage every year. Fungicide treatment should be started at the first symptoms of leaf spot and continued as needed. nine0003

    Resistant varieties. Selecting disease-resistant and disease-free varieties for new crops is important to prevent the introduction of the disease into new areas. Varieties "Ami Pasquier", "Ayesha", "Blue Bird", "Forever Pink", "Fuji Waterfall" ("Fujinotaki"), "Miyama-yae-Murasaki", "Seafoam", "Taube", "Tricolor", and 'Veitchii' have been rated as resistant to moderately resistant to many pathogens including Corynespora leaf spot in full sun.

    Phomosis (phoma rot) (Phoma)

    The disease can sometimes cause spots on hydrangea leaves. Phoma exigua has been reported to cause leaf spots in hydrangeas in various parts of the US and central Italy.

    Symptoms. Phoma leaf spot is characterized by small necrotic spots surrounded by chlorotic halos on the upper side of infected leaves. Leaf spot color may vary slightly by cultivar, H. macrophylla 'Lady in Red' cultivar developed small reddish brown lesions, 'Seafoam' cultivar developed large light brown lesions during pathogenicity tests with Phoma exigua. nine0003

    Biology and epidemiology. The development of phomosis is favored by relatively low temperatures (24 ± 3 °C). Severely infected leaves become chlorotic and fall off, leading to premature defoliation. Infected plants rarely die, but the presence of lesions on mature plants reduces the aesthetic quality and subsequent market value.

    Treatment

    Prevention. Cleaning and removing diseased leaf debris helps eliminate the source of the infection. nine0003

    Myrothecium leaf spot (Myrothecium roridum)

    Symptoms. In H. macrophylla, brown necrotic lesions with concentric rings and ash-colored centers characterize this disease and are similar to the symptoms of M. roridum in other ornamental plants such as sage, gardenia, begonia, and Hawker's balsam. The pathogen causes damage to the stems, mainly starting from the soil line, yellowish-brown concentric spots on the leaves, yellowing and wilting of the foliage. nine0003

    Biology and epidemiology. M. roridum lives primarily in the soil and has a wide host range consisting of several vegetable, agronomic and ornamental crops. Infected plant materials and contaminated soil spread M. roridum spores, fungal spores can remain viable for 2–3 months in field soil at 20°C.

    Treatment

    Prevention. Soil disinfection with fumigants or steam and soil solarization to kill pathogens. Preventive measures focus on sanitary procedures to reduce the incidence. nine0003

    Resistant varieties. Disease resistance is the best method for controlling hydrangea leaf spot. Of 88 H. macrophylla cultivars exposed to natural leaf spot pathogens in McMinnville, Tennessee, USA, ten cultivars: 'Ami Pasquier', 'Ayesha', 'Blue Bird', 'Forever Pink', 'Fuji Waterfall' ('Fujinotaki ”), 'Miyama-yae-Murasaki', 'Seafoam', 'Taube', 'Tricolor' and 'Veitchii' were rated hardy or moderately hardy in full shade, full sun and partial shade. nine0069 These cultivars can be considered to have multiple resistance to pathogens including Cercospora spp., C. cassicola, C. gloeosporioides, M. roridum and P. exigua.

    Alternaria leaf spot

    Hydrangea blight can be caused by several Alternaria species reported in Italy and the USA. Infected plants rarely die, but the presence of damage reduces the aesthetic quality and commercial value.

    Symptoms. nine0070 The initial symptoms of Alternaria are small brown spots with yellow halos that appear on the upper surface of affected leaves. The lesions then turn dark brown or black and often coalesce into large necrotic areas. Symptoms are usually observed on the edges of the leaves and near the petioles. Severely affected plants undergo defoliation (falling off).

    Biology and epidemiology. Two species, A. alternate and A. compacta, have been identified on Hydrangea largeleaf and Hydrangea petiole, respectively, in Italy. Alternaria blotch pathogens can survive as mycelium or spores in plant debris. In humid conditions, the spores of the pathogen are spread by wind, rain or irrigation, causing disease epidemics in landscapes and nurseries. Therefore, periods of wet conditions due to rain and overhead irrigation are favorable for disease development. nine0003

    Treatment

    Prevention. Increase planting distance to improve air circulation. Avoid overhead watering, water the plants in the morning so that the water from the surface of the leaves evaporates quickly. Properly heat and ventilate greenhouses to reduce humidity.

    Sanitation. Remove infected leaves from infected plants and destroy or discard.

    Fungicides. The use of fungicides is part of comprehensive disease control programs. Since most fungicides are preventive, the first application should be started when the disease is detected in nurseries or landscapes. The application interval should be in accordance with the recommendations on the label. nine0003

    Bacterial diseases

    Xanthomonas campestris

    Bacterial leaf blotch caused by the pathogen X. campestris is a common problem for large-leaved hydrangea, oak-leaved hydrangea and hydrangea. The disease was reported in the United States (1996).

    Symptoms. In Hydrangea oakifolia, the first symptoms of the disease are watery spots on the underside of the leaves, then develop into angular purple lesions, as the lesions are usually confined to the veins of the leaf. The disease usually starts in the lower leaves and spreads up the plant. On Hydrangea macrophylla and Hydrangea arborescens, symptoms appear as small, purple, angular spots. In the late stage of lesion development, necrosis develops in the center of the lesion, which dries up, turns brown, and can often fall out, giving the appearance of a hole. nine0003

    Biology and epidemiology. Humid to moderately humid conditions favor disease development in greenhouses, nurseries and landscapes. Infection begins on lower leaves, then spreads to upper leaves and neighboring plants as the pathogen is carried by splashing water. Small watery spots appear on leaves within 3-5 days of infection, typical purple spots appear within 7 days.

    Treatment

    Prevention. Avoid overhead watering to prevent spread of infection through splashing water. Place plants in sufficient numbers to improve air circulation. Water the plants in the morning and do not touch wet plants. nine0003

    Sanitization. Immediately remove and discard severely infected leaves during the growing season. At the end of the season, remove and destroy fallen leaves.

    Fungicides and biological control. Kaolin clay (Surround) and Neem Oil (Neem Gold) have been reported in field experiments to reduce the severity of bacterial leaf spot disease. Copper-containing fungicides may provide some control when applied in late spring, but will not be effective on plants grown in disease-friendly conditions. nine0003

    Bacterial wilt (Ralstonia solanacearum)

    Viral diseases

    Hydrangea mosaic virus (HdMV)

    The virus can be mechanically transmitted by grafting, contact with leaves or tools, but not by aphids or seeds. Control of HdMV includes the use of virus-free transplants and cuttings from healthy plants. nine0003

    Hydrangea ringspot virus (HRSV)

    Early symptoms of HRSV on hydrangea leaves are brown spots or rings, followed by leaf distortion, leaf curl and stunting. The virus can be transmitted mechanically through juices, but aphids or seeds do not transmit HRSV. Cultural control of HRSV includes the purchase of clean plants and the disinfection of pruning tools.

    Tomato ringspot virus (ToRSV)

    ToRSV has a wide host range including woody and herbaceous plants. On hydrangea, the virus causes leaf deformation, chlorosis and stunting of plants. The virus can be transmitted by nematodes, but not by pruning tools. Control strategies for ToRSV are weed control and the use of a nematode-free potting mix for container growing. nine0003

    Tobacco ring spot virus (TRSV)

    TRSV is widespread in trees and herbaceous plants in North America, and also occurs in Europe, Asia and Australia. Various symptoms can be found on infected plants, including leaf malformation, leaf chlorosis, and stunted plant growth. Nematodes of the genus Xiphinema are the main carriers of the virus. TRSV control strategies include planting clean stocks in containers in soilless environments and controlling weeds that can be reservoirs for virus and nematode vectors. nine0003

    Tomato spotted wilt virus (TSWV)

    TSWV infects more than 1000 plant species. The virus is transmitted by thrips. Prevention is the first step in disease control and can be achieved by purchasing virus-free plant material. In greenhouses, control of TSWV can be achieved by killing infected plants and by killing thrips.

    Cherry leaf rasp virus (CLRV)

    CLRV is widespread in Eurasia and North America, also found in Australia and New Zealand. Symptoms of CLRV in hydrangeas are leaf distortion, chlorosis, and necrotic spots. The virus can be transmitted through seeds and pollen, through vaccination. Because CLRV is a relatively new disease in hydrangea and no effective control methods have been reported, the use of clean and virus-free plant materials is effective in preventing the introduction of the virus into nurseries and landscapes. nine0003

    Alfalfa mosaic virus (AMV)

    AMV has a wider host range, including 150 plant species, and is widely distributed throughout the world.

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