The appearance of black spots on rose leaves is an alarming signal. If the plant is not treated, it may completely lose its decorative properties, and in severe cases, die.
Causes of black spots on roses
Rose is very whimsical. If there are errors in care, its leaves, and sometimes shoots, are affected by the fungus Marssonina rosae - the pathogen black spot(PE). After powdery mildew, this is the most common problem with roses. It is easy to determine the emergency: first, brown round spots with a yellow border form on the lower leaves, then they turn black, their shape spreads out like a blot on a blotter.
Black spotting is a dangerous disease that requires immediate treatment.
The disease most often develops after the end of the first wave of flowering against the background of:
- damp, windless weather;
- unsuccessful planting of a rose in the shade;
- the presence of last year's foliage on the soil;
- the density of the bush itself and the plantings around it;
- excessive watering;
- overfeeding with nitrogen fertilizers.
Over time, the disease takes hold and upper tier, the affected leaves turn yellow and fall off. A rose that is sick with an emergency becomes so weakened that it can freeze out in winter.
With heavy rainfall and lower night temperatures, roses are affected by a variety of fungal diseases
Black spot treatment
Urgent measures will help save the plant. First, diseased, drying leaves are removed from the rose, green ones are left, they are necessary for photosynthesis. Fallen leaves are removed, the ground under the bush is sprinkled with ash. Plant residues are burned, they cannot be put into compost, as fungal spores remain on them.
In case of severe damage, when the emergency affected half the bush, apply chemicals containing copper: Bordeaux mixture, HOM or Oxychom.
Treatments are carried out in the evening every 14 days in the absence of precipitation and once every 7 days in rainy weather until the plant is healthy. The top and bottom sides of the leaf are sprayed.
Many experienced rose growers use the drug HOM for the treatment and prevention of any rose diseases On early stages
- Drugs containing triazole are effective in emergency situations:
- Bayleton;
- Speed;
- Topaz;
Fungicides penetrate fungi and disrupt their growth, but they are powerless against germinating spores. Therefore, the listed drugs are alternated with chemicals containing mancozeb, which inhibits the maturation of spores:
- Ridomil Gold;
- Metaxyl;
- Ordan;
- Profit.
Spray the plants with the above products alternately once a week. Usually 3-4 treatments are enough to suppress the emergency.
Fungicide Ridomil Gold is often used for diseases of roses, grapes, fruit trees and tomatoes
At mild form In an emergency, when only 2–4 leaves are affected, you can limit yourself to Fitosporin: 4 treatments every 5 days.
If at least one rose in the flowerbed is sick, you need to spray all the other bushes too.
How specialists treat emergencies - video
Prevention of fungal diseases
Victory over a state of emergency is a temporary phenomenon. The fungal spores are carried by the wind and will again try to settle on the roses. It is realistic to only reduce the likelihood of disease by increasing the immunity of plants with the help of proper care.
- plant varieties of roses that are immune to emergency situations, for example, modern hybrids from Kordes;
- treat new seedlings before planting with beneficial bacteria, for example, the biological product Fitosporin-M;
- add three-year-old humus or compost to the soil to improve the microflora around the bush;
- lime if necessary, too acidic soils promote the development of fungal diseases;
- maintain sufficient distance between bushes for good ventilation;
- promptly prune weak shoots that thicken the bush;
- in the spring, spray with copper or iron sulfate before the buds open, and in the fall - before covering the roses for the winter;
- for prevention, treat roses with biological products or fungicides against spotting during the summer;
- feed the bushes with potassium in early June and potassium-phosphorus fertilizers in August;
- Trim and burn rose foliage completely before winter covering.
Gradually, rose growers are moving away from mono-plantings of roses and planting plants in the neighborhood that are resistant to fungal diseases: lavender, sage, marigolds.
In the second year after planting the rose garden, many of my bushes became infected with black spot. As it turned out, there is no need to feed roses with nitrogen fertilizers in the spring if they were introduced into the planting hole at autumn planting. Overfed roses will always develop fungus.
Very good results This year I got it by hilling roses with old compost for the winter. This procedure significantly increased their immunity. In May and June I carried out preventive maintenance: I sprayed the roses with the fungicide HOM, and in July with Skor. There are almost no diseases, despite the rains. I remove all the leaves from both sick and healthy roses in the fall.
Varieties of roses resistant to black spot - photo gallery
Variety Sympathie - winter-hardy rose, often grown as climbing variety Augusta Louise - profusely blooming hybrid tea rose Westerland variety is the best bush rose Yankee Doodle variety - hybrid tea rose with flowers that change shade
More often weakened or improperly planted plants suffer. In addition, neglect of care will inevitably lead to the occurrence of diseases and developmental problems.
For good growth For roses to bloom beautifully, they need constant attention from the gardener. Preventative examinations and the ability to immediately identify the first warning signs make it possible to quickly prevent almost any illness.
Quite often, the “queen of the flower garden” gets sick due to:
- weather conditions (for example, high humidity or prolonged heat);
- poor lighting, insufficient air access;
- crowded conditions in the rose garden;
- mechanical damage to stems and root collars.
Causes the most damage infectious diseases, the causative agents of which are fungi, viruses, and bacteria. But there are also functional diseases: they appear when there is a deficiency of any element in the soil.
What are the diseases of roses?
Powdery mildew
In summer, powdery spots of a whitish-gray coating are often found on roses, which later acquire a grayish-brown color. Buds and shoots die, leaves curl. This is how powdery mildew manifests itself: its causative agent is Sphaerotheca pannosa. The fungus overwinters on stems and plant debris. The appearance of plaque - sure sign the fact that the flower is overfed with nitrogen fertilizers, but is deficient in potassium.
In addition, it is not recommended to irrigate by sprinkling in the evening: such procedures are more useful in the morning or afternoon. Bushes planted in a dense pattern, and even in a poorly lit place, are more susceptible to attacks by pathogens. Powdery mildew is easier to prevent, because then you will have to fight with it for several seasons.
So what to do:
- for preventive purposes, the rose garden, including the ground around it, is pollinated with ash, and also sprayed once a week with mullein infusion in the usual proportion of 1:10;
- affected branches and buds are cut to a healthy place and burned. The plantings and soil are treated with Bordeaux mixture (usually 1%) three times every ten days;
- of systemic fungicides are suitable for spraying Topaz, Skor, Vectra.
Gray rot
Fungal spores Botrytis cinerea suppress the growth point of young shoots, affect buds and buds, which rot without even opening. On the petals you can see characteristic brown sores, the leaves turn yellow. Wet weather promotes the development of a gray fluffy coating on the stems.
The fungus is activated by thickened plantings, high humidity, and also due to a lack of potassium and phosphorus in the soil. Multi-petalled varieties, predominantly white, cream, and yellow in color, are severely affected by gray rot.
What to do:
- pink solution of potassium permanganate is the best prophylactic: You can spray or water bushes with it;
- cut out infected parts and remove from the area;
- try to create the maximum possible dryness in the rose garden, feed with phosphorus and calcium 2:1;
- effective spraying with drugs Vectra, Fundazol, iron sulfate.
Black spot
Fungus infection Marssonina rosae occurs in late spring, and the first symptoms appear only closer to August. Brown or black spots form on the leaves; they quickly enlarge, spreading over the surface. A weakened bush sheds its leaves and blooms very poorly. Black spotting begins to progress when high humidity.
It is quite difficult to get rid of the disease, since the fungus survives well on fallen leaves. Therefore intense spring pruning, cleaning up last year's plant debris and mulching are extraordinary methods of treatment. By the way, yellow varieties are more prone to black spotting.
Fighting methods:
- Be sure to pick off diseased leaves;
- in sunny weather, the bushes are doused with a soda solution (half a glass per 3.5 liters of clean water);
- next folk way- dilute a glass of milk in 12 liters of water and give the “victims” a shower;
- processing of plantings Zineb, Benlat, Topaz, Skor, Fundazol. Bordeaux mixture can also help, as well as copper sulfate.
Rust
Particularly strong rust fungus of the genus Phragmidium Remontant, park varieties, and rose hips are affected. In spring, bright red pustules with spores appear on the root collar, shoots, and at the bottom of the leaf blade. Already in July they turn black, the leaves fall off, the shoots become deformed and dry out. Fighting rust is very difficult, especially in rainy summer. If a rose is severely damaged, it cannot be treated: such specimens are destroyed.
Treatment methods:
- do it for prevention foliar feeding extract of superphosphate (0.3%), potassium nitrate (0.3%);
- the affected parts must be cut out, the fallen remains raked and burned. After each trimming, the instrument is treated with denatured alcohol;
- planting, the ground around is sprayed with copper-containing preparations, as well as Topaz, Profit.
Viral mosaic
Characteristic signs of viral mosaic are the appearance on leaf blades yellow stains. In addition to the marbled pattern, the leaves often become wrinkled, very narrow, and curly. Plants weaken, their growth slows down, and they quickly die. The spread of viral mosaic is often caused by aphids, mites, and rose grafting.
The disease is easily transmitted through tools, hands, and gloves. Sick specimens are not used for reproduction. Some gardeners are in no hurry to dig up diseased bushes if they are still quite strong: they are fed with fertilizers containing a full composition of microelements. Plants that are too affected are, of course, destroyed.
Leaf spotting is not typical for ornamental plants who are bursting with health. If you notice spots of black, yellow, red or rust on your roses, most likely they are kept in unfavorable conditions or are under stress. Discoloration of leaves may also be a sign of disease. How to find out why spots appeared on your pets and what measures to take to revive the plant?
The appearance of brown spots may be a sign of brown spot (cercospora). With this disease they also have a black border. The causes of fungal disease are associated with high temperature and air humidity. The presence of dark brown spots may also indicate fungal infections such as septoria, pestalocin, and phyllisticosis.
The signs of all these diseases are similar to each other, so making a final diagnosis will not be easy. In this case, you should not puzzle yourself, it is enough to carry out the processing chemicals to combat fungal diseases.
Black spots on roses
If June is cool and rainy, dark spots may form on the roses, which soon merge and turn black. Where they occur, swellings (round or oblong) can be observed. A disease of this type is called black spotting. The causative agent in this case is the fungus Marssonina rosae. Soon the leaves fall off, the plant weakens and refuses to bloom. Black spot can be confused with false spot powdery mildew. However, the latter is characterized by spots different color(they can be black, red-brown, purple).
Description
Fungal disease caused by a fungus Marssonina rosae. It overwinters as conidia on fallen leaves and shoots. At the beginning of spring wet weather Its fruiting bodies develop on necrotic tissue or weakened plants. Then, at high humidity (about 86%) and at a temperature of about +8°C, spores are spread with drops of moisture - mainly by dew, rain, or when watering the leaves. Young leaves and shoots, less often sepals, are affected. Signs of the disease appear closer to July. Then it becomes obvious why the disease received such a name.
5 to 10 days after infection, the foliage becomes covered with uneven, rapidly expanding black-brown spots about 5-15 mm in size, sometimes with yellowish edges. The same spots can be found on young shoots. Affected leaves turn yellow and fall off. Severely affected bushes shed their leaves almost completely and stand, as they say, bald. Sporulation occurs throughout the growing season, so repeated “outbreaks” of the disease are possible.
It is especially dangerous for young plants, which, having lost their leaves, are greatly weakened and stunted in growth, as a result they can freeze out or be severely damaged in winter.
Factors
The severity of the disease, as well as the ability to resist it, depends not least on the chosen variety. Most manufacturers indicate in the description of the variety its susceptibility to black spot. For example, in the catalogs of the German company Kordes, three stars will be drawn next to the word “sternrusstau”. How many of them are completely painted over is the stability of the variety, according to the breeders. For example, varieties "Romanze", "Schneewittchen", Maiden's Blush","Bernstein Rose", "Leonardo da Vinci" classified as weakly resistant. Modern hybrids are generally more resilient than antique roses (according to collectors, many Bourbon roses and fetida rose hybrids ( r.foetida) are blacklisted).
The planting location also has an effect - in heavily dense plantings, where moisture from the leaves does not evaporate well, the disease spreads faster.
A factor that does not depend in any way on the gardener is the weather. If it is warm and damp, then black spot is especially active.
Prevention
Do not leave foliage on roses under winter shelters - pathogens overwinter on shoots and in plant debris.
Before laying roses for the winter, the soil must be treated with a copper-containing preparation.
After pruning, the affected shoots must be burned; they cannot be used for compost. Fertilizing also affects the resistance of plants to diseases - they must be balanced and include the entire complex of microelements, without bias towards nitrogen. Regular, once a week spraying with a weak solution of mullein or horsetail infusion (1:20), dusting young plants with ash helps.
Do not buy container plants with signs of disease, as well as unstable varieties.
Control measures
Varieties susceptible to the disease must be treated for preventive purposes according to the following scheme. The first time - at the beginning of leaf dissolution and a week later (in the phase of 2-3 pairs of open leaves) and before flowering with a solution copper sulfate(you can use "Oxychom"). Before the second wave of flowering, the treatment must be repeated. At the first signs of disease, spray roses with preparations containing mancozeb (Profit, Ridomil Gold) and penconazole or triazole (Skor, Topaz). You can try "Fitosporin" or "Tiovit Jet". In case of deterioration climatic conditions It is useful to support plants with immunostimulants (Zircon, Epin - Extra).
In order not to cause the plants to become addictive, especially in collection monoplants, the preparations need to be alternated. If the weather is rainy and it is not possible to treat the roses in a timely manner, frame arches can be installed over especially valuable varieties, over which a plastic film is stretched like a roof so that the preparation is not washed away by precipitation.
Agree, having a beautiful and healthy flower garden in your garden is very nice. It’s especially nice when queens of flowers are fragrant in the garden all summer long. But, unfortunately, this joy can quickly be overshadowed by various fungi, viruses and insect pests. Frequent disease roses - black spotting, when black spots appear on the leaves of roses and you need to know how to treat them. In this article you will learn how to solve this problem and what methods help to get rid of the disease.
Unfortunately, black spot on roses is considered almost the most dangerous disease, which is not so easy to get rid of; in some cases, even the best drugs may be useless.
First of all, black spot affects diseased and young shoots. Spring favorable time for the development of fungus, since at this time the humidity is high. If the infection occurred in the spring, then signs of the disease may not be visible immediately, at least after a month.
If the weather is warmer (up to 30C), then the fungus develops rapidly and after 10 days you can see the first signs. The fungus does not like dry and hot weather, therefore, it dies at a temperature of 35C.
Black spotting can also occur in roses due to lack of nutrition, especially if the plant lacks potassium.
Favorable conditions for the development of black spotting
- Insufficiently lit place;
- Heavy, clay soil;
- Weeds (need to be removed regularly);
- Dense planting of bushes;
- Lack of nutrients;
- Excessive watering;
- Improper pruning (using dirty, untreated tools;
- Unfavorable weather(rain, dampness).
Symptoms of black spotting
As I wrote above, the first signs of the disease do not appear immediately. You can only find out that the plant is sick in the second half of summer. But when the first signs appear, the disease spreads very quickly.
First, dark brown spots with yellow edges appear on the leaves of roses. Gradually the leaves turn yellow and die. Dark spots also appear on the stems. Flowering stops. As a result, the rose stops growing, loses its foliage and takes on an ugly appearance.
Unfortunately, black spots on roses are difficult to treat, and sometimes any action may be in vain. Therefore, it is easier to prevent a disease than to treat it.
“The best fight against black spot on roses is prevention”
Treatment of black spots on roses should begin, as they say in advance, before planting the rose in open ground and even before purchasing it. Therefore, we will start by buying roses.
- You need to buy roses only in a special store, or a gardening farm, where the likelihood of a disease occurring can be equated to zero.
- Give preference to varieties in which the risk of spotting is minimized. Fortunately, most modern varieties have this feature.
- After purchasing a rose, choose a suitable area for planting so that everything meets the needs of the queen of flowers.
- Do not plant roses in places where roses grew less than 5 years ago, or other plants that suffer from the same diseases as roses.
- Try to follow the proper care rules based on the plant variety.
- Be sure to inspect the plant regularly for suspicious symptoms. This will help you on early stages identify the disease and immediately take appropriate measures.
If you regularly inspect the plant for disease, the disease can be detected in the early stages before it has spread and infected the entire plant. If you notice the first signs of the disease, be sure to remove all damaged parts (leaves, shoots, flowers), sparingly.
- At the initial stages, the plant can be sprayed with horsetail infusion (pour 1 kg of fresh grass, or 150 grams of dry bucket of water and leave for 24 hours, then boil the infusion for 30 minutes, let cool and strain. Dilute the infusion with water 1:10).
- Every 10 days, spray the rose with sulfur-containing preparations.
- It is also recommended to spray roses with preparations containing copper (at any time of the year copper - soap solution, and in the fall 5% copper sulfate).
- If no measures help, then resort to a last resort - we treat the plant with Bordeaux mixture every 7 - 10 days. We water the soil around the bush with the same solution. This drug is very toxic, both for humans and for environment Therefore, we take all precautions.
“For preventive purposes, you can add fungicides to the soil while loosening the soil.”
You can buy other drugs in a specialized store that contain substances such as triazole and mancozeb. For the first seven days, roses are treated with preparations that contain mincozeb, and after a week they are treated with preparations containing triazole.
Plants should be treated in dry weather to avoid dew on the leaves. Before treatment, the plant must be watered and sprayed with a solution.
When the black spots on the plant disappear, still be vigilant and inspect the plant more carefully and more often than before the disease. If symptoms recur, the diseased leaves are removed and burned, and the rose is again treated with drugs.
Well, now you know why black spots appear on rose leaves, what to do about it and how to treat the plant. I also told why roses suffer from black spot, what control measures exist, what drugs can be used for treatment. I hope these recommendations were useful to you and you found answers to your questions.
I will be glad to see your feedback and comments. If you tell us about your experience and how you treat your plants, I would be very grateful.