How to treat spot on rose leaves?

How to treat spot on rose leaves?

Roses are undoubtedly an adornment of any garden, but in order for them to grow well and please with their appearance, they need quality care. One of the main problems that a gardener may face will be black leaf spot.... This disease belongs to fungal and very quickly destroys the plant. Let's talk about preventive measures and how to treat this disease.

Reasons for the appearance of black spots

In order to carry out effective treatment of any disease, it is necessary to know the cause of its appearance, which must be eliminated as soon as possible.

There are several reasons why black spot appears on the leaves of a rose.:

  1. If as the landing site for the rose was chosen low or a very thickened area, the evaporation of moisture will be greatly slowed down, as a result of which the fungus will multiply and spread as quickly as possible;
  2. In warm and damp weather mushroom spores become active, and the roses begin to become covered with spots;
  3. Incorrect feeding (lack or excess) can also cause the development of the disease;
  4. It is also very important take good care of flowers and stop any provoking factors in time.

Black spot is caused by a fungus called Marssonina rosae, it has a detrimental effect on the leaves of the plant and is transmitted through dew or rain.

Favorable conditions

The development of black spot on the leaves of a rose can be facilitated by factors that do not depend on a person, for example, wet weather or a large amount of rainfall. Also the reproduction of the fungus is affected by the lack of air circulation and the strong thickening of the shrub.

Also, experienced gardeners recommend finding out in advance full information about the acquired variety, including resistance to black spot. If the plant is immune to the disease, then the risk of infection will be minimized, otherwise the fungus can comfortably multiply on the leaves of the rose.

Symptoms

Usually, the disease begins to manifest itself in the second half of summer, it is also possible that several outbreaks of spotting occur in one season. The parasitic fungus attacks the soft, green part of the rose, namely the leaves and young shoots.

Most often, polyanthus, tea or climbing varieties are affected by the fungus.

Experts identify the following signs of black spot:

  • bush stops growing and develop;
  • dark spots on the leaves can reach 15 centimeters in diameter;
  • shape of spots resembles the sun;
  • disease develops from the bottom up;
  • gradually a few small spots combine into one;
  • affected leaves turn yellowroll up and fall off;
  • bushes thin out sharply, the colors are formed much less.

Black spot is very similar to powdery mildew, you can distinguish them by the sign that the spot rises from the bottom up, gradually gaze at the whole plant.

Treatment

There are several ways in which you can get rid of the disease, but the initial method will be to cut and burn the affected foliage. Many amateur gardeners are very mistaken, thinking that if the rose sheds its leaves in the fall and overwinters, the disease will disappear.... Unfortunately, this is not the case, the spores of the fungus survive well in the soil and again infect the plant.

Chemicals

Immediately after the detection of the disease, the rose must be treated with fugicides, the active ingredients of which are zinc and mancozeb. The procedure is repeated every 2 weeks., while it is recommended to spray the bush with various preparations in order to avoid the addiction of the fungus. The most effective remedies are considered:

  • Profit;
  • Ridomil Gold;
  • Speed;
  • Strobe;
  • Oxyhom;
  • Copper chloroxide.

You can also use Brodsky liquid, with the help of which not only the plant is processed, but also the soil. Similar procedures are repeated until the spotting stops growing.

Biological preparations and folk methods

In addition to chemicals, you can use biologically active drugs that are less harmful to the environment, but in some cases are less effective. That is, they will be useful in the initial stages of the disease, when the growth of spotting can be quickly stopped.

The drug Fitosporin-m has proven itself well, with which it is necessary to spray the plant and water the soil every 5-7 days... The number of procedures is not limited, only the minimum number is indicated - 3 treatments.

Traditional methods are the most accessible, they can be used upon the first detection of spotting:

  1. Infusion prepared onion peel-based;
  2. Dandelion infusion, nettle or horsetail;
  3. Also helps well infused cow dungdiluted with water;
  4. Many gardeners insist on ordinary grass;
  5. Another way would be applying crushed ash to the plant.

To prevent the growth of fungi, the best and cheapest method is an infusion of horsetail or nettle.

Other rose diseases characterized by leaf spot

In addition to black leaf spot, the rose can suffer from the following diseases that affect its foliage:

Cercosporosis

Infection with the cercospora fungus is provoked. This disease manifests itself in the form of small, round spots of brown color.appearing on foliage and young shoots of shrubs. An interesting feature is that the shade of the border of the spot is darker than its middle. After a certain time, white mushroom bloom can be seen in the infected areas.

Schaceloma

The causative agent of the disease is the fungus of the same name. On the upper side of the leaf there are purple spots, the framing of which is painted black, and the presence of dark crimson stripes is also characteristic. Gradually, the purple color changes to gray, which is due to the formation of spores. On the underside, brown solid formations can be seen. The color of the spots on the stem is similar to the spots on the foliage.... The only difference will be that the shape changes from round to oblong. In this case, the formations become convex.

Peronosporosis

The second name of the disease is downy mildew. Initially, purple or dark red spots of arbitrary shape are formed on the leaves, upon closer examination, you can see a thin cobweb on them. Then the leaves roll up into a tube and die off. The stems become cracked, the buds also lose their vitality.

Having considered several diseases, we can come to the conclusion that rose spot is caused by a fungal pathogen, a favorable condition for which will be humidity, warmth, shade, stagnant air, etc.

Prophylaxis

As a preventive measure, it is necessary to properly care for the shrubs and perform the following actions:

  1. First of all, it is necessary keep the flower garden clean and remove weeds in time;
  2. Held in spring and autumn sanitary pruning, during which all dry and damaged branches are removed, it is also necessary to discharge the crown of the bush so that the air can move calmly;
  1. Plants should be planted this wayso that when one shrub is infected, the spread of the disease throughout the garden can be avoided;
  2. The acidic environment is favorable for the fungus, therefore the soil must be limed or add dolomite flour;
  3. Roses need timely application of phosphorus, potash and complex mineral fertilizers, and nitrogen fertilizers obtained in large quantities can harm the plant. Therefore, it is very important to observe all proportions during feeding;
  4. It is recommended to loosen the soil before wintering.so that the mushroom spores rise up, and come under the influence of cold temperatures, and as a result of which they die;
  5. When preparing shrubs for winter, it is necessary collect and burn diseased foliage, cover roses only in the complete absence of leaves.

Preventive treatments

  1. When preparing a rose for winter and immediately after the snow has melted the soil is treated with copper or iron sulfate, while drugs are recommended to alternate;
  2. Well proven treatment with growth stimulants and drugs to improve the immunity of the rose;
  1. When the first foliage appears the plant is sprayed with chemical (1 procedure) or biological (2 procedures with an interval of 5-7 days) preparationsabove.

During processing, the air temperature must be at least 15 degrees.

Another preventive method will be the correct neighborhood, that is lavender can be planted next to roses, calendula or sage. Every gardener should remember that disease is easier to prevent than to cure.

The leaf spot of a rose is caused by the presence of a fungus, the danger of the disease is that it spreads very quickly and it is quite difficult to protect healthy plants from it. In order to avoid the appearance of spotting, it is necessary to provide proper care for the shrub.... But if the infection does occur, the treatment will take a fairly long amount of time.


Pests and diseases of roses

The defeat of roses by diseases and pests can significantly reduce their decorative effect, and in some cases lead to the death of plants [1].

Pathogenic mycoflora of roses has about 270 species [2]. In the conditions of Moscow and the Moscow region, there are about 49 species of phytophagous insects, including 32 leaf-eating, 13 sucking, 2 mining and 2 gall-forming. The most harmful species in all groups and varieties of roses are the rosaceous downward sawfly (Ardis brunniventris Htg.), Rose aphid (Macrosiphum rosae L.) and common spider mite (Tetranychus urticae Koch.) [3].

The work of rose breeders is aimed at breeding varieties that are resistant to fungal diseases [2].


What is black spot of roses: reasons, when and how it manifests itself

This disease causes a fungus. Marssonina rosae.

The fungus hibernates on leaves and shoots, as well as in the soil, more precisely, in plant debris (in the same fallen leaves). In spring, spores spread through the garden along with winds and rains (+ fogs).

As a rule, fungal spores infect the plant at the beginning of the season, i.e. in spring and early summer (under favorable conditions), however, the first signs of the disease appear only in the second half of summer (July-August).

Marsonia (Marssonina) = black spot (many are used synonymously).

What does the lesion of the leaves of a rose with black spot look like?

  • As a rule, leaves that are closer to the soil (i.e. below) are affected first. Round or "blot-like" (with wavy edges) black spots appear on them, and these spots can be observed both from the outside and from the inside of the sheet. Over time, black spots begin to appear on the upper leaves.
  • Then they gradually merge and turn yellow, dry and fly around.

Favorable conditions for the development of the disease:

  • wet rainy weather
  • cold nights (strong fluctuations in night and day temperatures) and morning dew
  • evening watering, when the roses do not have time to dry.

In other words, if summer is wet and cold (it often rains and the nights are cool), then black spots will surely appear on the leaves of your roses, if you do not take preventive measures to protect them.

Also, the site of planting, more precisely, an unfavorable microclimate, also affects the defeat of black spot and other fungal diseases. So, in lowlands and poorly ventilated areas of the garden, dew is more often formed at night.

Remember! Roses need to be planted in sunny and well-ventilated places, while not too close, so that there is no thickening. It is also very desirable that the place be illuminated in the morning by the sun, which will dry out the morning dew.

What is the danger of black spot for roses?

  • Slightest touch to infected leaves causes them sinking.
  • If there is a strong infection of the bushes, then by the end of summer the plant is completely bare, i.e. will be left without leaves.
  • As a result, the rose will not only lose any decorative effect, but due to the weakening of immunity (due to the absence of leaves) the plant may simply freeze out in winter (or at least it is bad to endure the winter, grow poorly and bloom in spring).


Spots appeared on the leaves of the rose - what to do and how to treat the plants

Leaf spot is a common ailment of many ornamental plants. In this article, we will tell you why yellow, black, white, brown, rusty and red spots appear on the leaves of a rose.

If your roses are stained, then the flowers are sick or stressed because they are growing in the wrong conditions. Let's figure out what to do with it.

Brown and brown spots on roses

Brown spots on the leaves of a rose often indicate brown spot (cercospora)... Moreover, they usually have a black border. This fungal disease is provoked by high temperature and humidity.

Dark brown spots can also signal other fungal diseases of roses: septoria, pestalotia, phyllostictosis... According to the external signs of spots, these ailments are very similar, so it makes no sense for beginners to puzzle what kind of disease attacked the rose, but it is better to stock up on fungicides.

Black spots on roses

In early summer, especially if it is cool and rainy, dark spots may form on the leaves of roses, which gradually merge and turn black. In these places, swellings of a round or oblong shape often appear.

This disease is called black spot... Its causative agent is the mushroom Marssonina rosae. Over time, the affected leaves fall off, the plant's immunity decreases, flowering does not occur.

Symptoms are very similar to black spot. downy mildew... But with the last illness, the spots on the leaves of the rose can be not only black, but also reddish-brown, purple or purple.

Roses with glossy and leathery leaves are less susceptible to mottling.

White spots on roses

The most common cause of white spots on rose leaves is the fungus Sphaerotheca pannosa, which causes powdery mildew... It affects not only leaves, but also buds, shoots, fruits of plants.

First, a white spider or mealy bloom appears on the affected roses. Later it becomes brownish gray. The spores of the fungus form throughout the summer and are carried by the wind over long distances. The leaves of diseased roses curl, the plants weaken and risk dying during the winter. Dampness, thickening of plantings, excess nitrogen, calcium deficiency in the soil contribute to the development of the disease.

If small white spots and specks appear on the upper side of the rose leaves, then the reason for this may be rose leafhopper... This yellow insect (up to 4 mm long) is easy to spot. It hides on the back of the leaf along the veins, and if the plant is shaken, the leafhopper quickly jumps off or flies away.

The leafhoppers eat away the pulp of the leaves and suck the juice out of them. They usually appear in very dry and hot weather. Systemic insecticides (for example, Aktara) will help get rid of the pest.

Yellow spots on roses

Yellowing of the leaves is most often due to potassium and / or iron deficiency... In this case, the edges of the leaves turn yellow, and the veins remain green. Over time, the young leaves turn reddish purple. Most of the elements are lacking in roses growing on sandy and peaty soils.

To save the flowers, they need to be fed with potassium fertilizers (for example, potassium sulfate or potassium magnesium) at the rate of 1 tbsp.for 10 liters of water and 2-Z times per season to carry out foliar dressing with iron-containing preparations or Kemira Universal's complex fertilizer (1 tablespoon per 10 liters of water).

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Yellow-green mottling, which appears mainly on the lower leaves, is a sign rose mosaic virus... As a result, the leaves fall off prematurely, the number of shoots decreases.

It is impossible to save a diseased plant. It will be possible to avoid the disease if you carefully choose high-quality seedlings, and when pruning and grafting, disinfect the tool with a pink solution of potassium permanganate.

Red spots on roses

Bright purple and cherry leaves often appear in "sunbathing" roses. Plants that do not like bright light or are simply not used to it become covered with red spots - sunburn.

Such roses need to be shaded or transplanted to a new place.

Also, red spots on the leaves of a rose may appear due to a lack of such important elements as phosphorus, magnesium, nitrogen.

With a deficiency of phosphorus, the plants must be fed with superphosphate (1 tablespoon per 10 liters of water), magnesium sulfate or ash should be added to the soil to replenish magnesium, and spraying on the leaves with nitrogen-containing fertilizers will help to cope with a lack of nitrogen.

Rusty stains on roses

The most common cause of orange spots on rose leaves is a fungal disease called rust... First, in the spring, yellow-orange tubercles appear on the back of the leaves - places of accumulation of spores. Over time, infected leaves turn yellow and fall off. In summer and early September, more dark (rusty-brown) spots are formed.

High humidity contributes to the development of the disease, while dry weather, on the contrary, inhibits the spread of fungal spores.

How to treat fungal diseases of roses?

All leaves (including fallen leaves) and stems with spots must be removed and burned, and it is advisable to cut off the shoots at the level of 2-3 buds from the base.

Alternately (with an interval of 7-10 days), treat the bushes with preparations containing mancoceb (Ridomil Gold, Profit) and penconazole (Topaz) or difenoconazole (Skor).

Also, these funds can be used in early spring for the prevention of fungal diseases.

You need to process the bushes in the evening. Before disinfection, it is worth watering the plant at the root. Even when the spots on the leaves of the rose have disappeared, you should continue to inspect the plants regularly, as there is a good chance that symptoms may return.

In case of severe damage, the plants cannot be treated. They need to be dug up and burned until the infection spreads to healthy specimens.

To prevent rose diseases, the soil in the rose garden should be mulched with mowed chopped grass, and before each flowering, foliar dressing should be carried out with a 0.3% solution of superphosphate extract and a 0.3% solution of potassium nitrate - until the leaves are completely wetted. And in the spring, the bushes and the soil under them need to be sprayed with 3% iron sulfate.

A copper-soap solution also helps a lot: 200 g of soap and 20 g of copper sulfate per 10 liters of water. Also, do not forget about regular pruning of roses, thinning bushes and timely removal of all old and dry shoots.

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Take care of your roses properly! Then your favorite flowers will not change the color of the leaves and will delight you with lush flowering.


White spots on roses

The most common reason for the appearance of white spots on the leaves of a rose is a mushroom. Sphaerotheca pannosawhich calls powdery mildew... It affects not only leaves, but also buds, shoots, fruits of plants.

First, a white spider or mealy bloom appears on the affected roses. Later it becomes brownish gray. The spores of the fungus form throughout the summer and are carried by the wind over long distances. The leaves of diseased roses curl, the plants weaken and risk dying during the winter. Dampness, thickening of plantings, excess nitrogen, calcium deficiency in the soil contribute to the development of the disease.

If small white spots and specks appear on the upper side of the rose leaves, then the reason for this may be rose leafhopper... This yellow insect (up to 4 mm long) is easy to spot. It hides on the back of the leaf along the veins, and if the plant is shaken, the leafhopper quickly jumps off or flies away.

The leafhoppers eat away the pulp of the leaves and suck the juice out of them. They usually appear in very dry and hot weather. Systemic insecticides (for example, Aktara) will help get rid of the pest.


What is the danger for the plant

Black spot on roses is a dangerous disease. As you know, any ailment is much easier to prevent than to deal with its possible consequences later, but, as they say, anything happens in life. They did not carry out the timely prevention of diseases of the decorative culture or did not pay attention to the black and brown spots on the lower leaves - now we have to deal with what is already there.

Remember, the disease will not go away on its own. If you do not take emergency measures for treatment, then first the rose will drop the lower leaves, which already have dark spots, then all the remaining foliage will turn yellow and crumble. The disease gradually covers the entire plant, after one or two seasons, the rose will die.

Black spot is a fungal disease of Marssonina rosae that spreads through dewdrops or rain. Having found dark traces on the leaves of one ornamental crop and having not taken any methods to combat the disease, you should not be surprised when, after a while, you see similar symptoms on other plants of your rose garden.


How to treat roses for diseases: effective remedies

Without exception, all flower growers are interested in how to treat roses from diseases. The most effective remedies for rose diseases include the following drugs.

"Alirin-B" - a biological preparation based on beneficial microorganisms isolated from natural sources. Effective against powdery mildew of ornamental and other plants.

"Glyocladin" - an analogue of the well-known drug "Trichodermin". It is effective against a wide range of fungal diseases such as fusarium, white and gray rot, late blight, root and stem rot, black leg and cabbage keel.

"Gamair" - a drug designed to protect against a wide range of bacterial diseases: bacterial leaf spots, fire blight, bacterial cancer.

"Topaz" - systemic fungicide to protect ornamental, pome, stone fruit, berry, vegetable crops and vines from powdery mildew. This preparation for the treatment of roses against diseases can be used as a protective, therapeutic and exterminating agent also against rust. The drug is available in the form of an emulsion concentrate.

As a destructive agent with a high degree of damage by powdery mildew, "Topaz" is used in increased concentrations (up to 10 ml), after 2 sprays with an interval of 7 days.

The drug provides reliable protection against powdery mildew, even against a high infectious background. Topaz is not phytotoxic, does not stain the treated leaves and fruits. As a prophylactic agent, it reduces the number of treatments, as it lasts for 40 days. The drug meets modern safety requirements for humans and the environment. It is quickly absorbed by plants, which reduces the risk of the preparation being washed off by rain.

In order to avoid the appearance of resistance of pathogens of powdery mildew, "Topaz" is recommended to alternate with contact copper-containing preparations and colloidal gray and not to use on the same culture more than 4 times per season.

"Topaz" compatible with most of the drugs used in gardens for diseases and pests. The exposure rate is 2-3 hours after spraying.

And how else to treat roses from diseases and to prevent infections in the backyard?

"Pure color" - a new drug for the protection of flower and ornamental crops from diseases (fungicide).

Method of application: the required rate of the drug in a special container is dissolved in a small volume of water. Then, with constant stirring, the volume of the working solution is brought to 5 or 10 liters. The working fluid is prepared immediately before use and used completely on the same day. The deadline for the safe exit of people for manual work is in 7 days. The rate of action of the drug: 2 hours after treatment.

The period of protective action: with preventive treatments - 7-15 days, in conditions of intensive development of diseases - 7 days.

The therapeutic effect of the drug: within 4 days from the moment of infection. It is not recommended for amateur gardeners to mix this drug with other remedies when spraying plants.

"Pure color" is an analogue of the drug "Raek".

Fundazol - a systemic preparation and a seed dressing agent for protection against a complex of diseases.

When using the drug, fill the container for etching the planting material with 1/3 of water, then add the required amount of the drug, mix thoroughly and add the remaining amount of water.

Spray the plants with a freshly prepared solution in dry, calm weather, preferably in the morning (before 10:00) or in the evening (18-22 hours), evenly wetting the leaves. The working solution is not subject to storage!

"Fast for the protection of roses" from black spot, ornamental and fruit crops from a complex of diseases. It is a prophylactic and curative systemic fungicide. The contents of the ampoule must be diluted in water.

Spray with a freshly prepared solution in dry, calm weather, evenly wetting the plants.

Working fluid consumption: on a rose - up to 1 liter per plant; on flowering plants and ornamental shrubs - up to 10 liters per 100 m2.

Do not store the working solution! Exit time for Handicrafts: 3 days. Compatibility with other pesticides is impractical. The period of protective action is 7-14 days. Exposure time: two hours after treatment. Not phytotoxic. The cultures are tolerant to the drug. No resistance occurs. Low hazard for bees (class 3). Toxic to fish, do not enter water bodies.

"Copper oxychloride" (wettable powder) - one of the copper-containing preparations for the fight against diseases of vegetable and fruit crops.

When using the contents of the package (40 g), dilute with 10 liters of water. It is necessary to spray the plants with a freshly prepared solution in dry, calm weather, preferably in the morning (before 10:00) or in the evening (18-22 hours), evenly wetting the leaves. In the recommended doses, the drug is not phytotoxic. The period of protective action is 7-10 days.

The drug is dangerous for bees and fish, do not carry out processing during flowering. Do not allow to enter bodies of water.

These photos show effective remedies for the treatment of rose diseases:


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