Powdery mildew on roses and its treatment is a question that worries all gardeners. This is a dangerous fungal disease. It affects both fruit and ornamental crops. Roses are also no exception. They are very often affected by powdery mildew, and as a result the entire rose garden may die.
Treating powdery mildew on roses is not easy and requires certain knowledge. Experienced gardeners know what to do to remove white plaque on roses at home. First of all, you need to choose a suitable remedy for powdery mildew on roses.
Why is powdery mildew dangerous?
This is a rather insidious fungal disease. It appears suddenly and develops rapidly. If measures are not taken in time, the plant may die altogether. Many novice flower growers do not understand why a white coating appears on roses, and what danger it conceals. But a little time passes, and the flower can no longer be saved.
Therefore, it is very important to know what powdery mildew looks like and regularly inspect the plants in the garden, so that in case of damage, you have time to take action. And even if you have avoided this scourge, you definitely need to know in advance how to get rid of powdery mildew on roses.
Signs of defeat
The very first sign is a white coating on the leaves of the rose. Outwardly, it resembles as if the leaves were sprinkled with flour. A little later, as the fungal spores mature, transparent droplets form on the leaves. This is where the name came from - powdery mildew. A white coating also appears on the stems of roses, most often in the spring.
At the first stage, plaque is easily removed from the leaf. Then it kind of grows into it. In the advanced stage, brown inclusions appear. The leaf curls and dries.
In fact, the appearance of a white coating on roses does not always indicate powdery mildew. There is another insidious disease that has very similar symptoms - gray rot. It is quite difficult to distinguish them from each other. However, this is very important, since they have different pathogens and require different treatments.
Sometimes it is much easier to identify diseases by external factors. In general, both powdery mildew and rot are formed due to improper care:
- thickened plantings;
- excess nitrogen in the soil;
- rare, or conversely, too frequent watering;
- no loosening.
But powdery mildew requires high temperatures to develop. More often, the disease affects flowers in the spring or at the very beginning of summer.
For rot to develop, a low temperature of 12–15 degrees and high humidity are required. Therefore, if the weather is rainy and cool, then this disease can be assumed.
The nature of the damaged parts also differs. With powdery mildew, a white coating appears on the stems and buds of roses, as well as on both sides of the leaves. When rot occurs, plaque appears on the rose leaves from the underside.
Preventive measures
A plant that has recovered from the disease, even if it was cured in time, suffers from reduced immunity. This means that it will be unstable to other diseases. There may be difficulties with wintering. Flowering will be sparse.
To avoid such consequences, you need to take prevention seriously. What can you do to prevent a white coating from appearing on rose leaves? What do you need to know so that you don’t have to look for the answer to the question of how to treat powdery mildew on roses?
It is important to maintain regular watering. The soil should not dry out or be too wet for a long time. It is imperative to regularly loosen to ensure air circulation around the root system.
The main thing you need to know about powdery mildew is how it spreads. It is transmitted in many ways:
- by the wind;
- with water;
- from hand
If you have touched an infected plant, you should wash your hands thoroughly. Do not use water in which you have washed your hands. If one rose gets sick, the neighboring ones will also become infected with powdery mildew. They also need to be processed.
Folk remedies
If you have suffered from powdery mildew on roses, control measures must be taken immediately. But often, there is no store nearby, and home remedies are always at hand. Moreover, many gardeners say that they are no less effective than special means.
One of the simplest and effective means is a soap-soda solution. To prepare it you need to take 4 liters of water, dissolve a tablespoon in it baking soda and a teaspoon of laundry soap. You need to spray the plant three times, with an interval of one week.
You can use mustard powder. Two tablespoons should be dissolved in 10 liters of water, and the plant should be sprayed with the solution. Just as in the previous recipe, the procedure is repeated three times.
Effective in the fight against fungus and ash. A kilogram of ash is dissolved in a bucket of water. The solution is sprayed on the plants every other day and the soil is watered.
It is important that before starting treatment, you need to remove all affected leaves and flowers. If the fungus has already damaged them, then the treatment will not have an effect. Everything that has been removed must be burned.
Chemical attack
For moderate to severe rose disease, it is necessary to combat powdery mildew. chemicals. They can be divided into two types: ready-made industrial mixtures, and solutions prepared independently.
The first type includes “Fitosporin”, “Bayleton”, “Fundazol”. They can be purchased in specialized stores and used in accordance with the instructions. As a rule, the treatment is repeated until the symptoms disappear completely.
The second type includes Bordeaux mixture - a 3% solution is prepared from it. Copper sulfate dissolved in water, in the same 3% ratio. And also a half percent solution of copper oxychloride.
Rose varieties resistant to disease
Breeders, when developing new varieties of roses, of course, pay attention to their resistance to diseases. Have the greatest resistance hybrid tea roses, florinbunda and scrubs.
When choosing varieties that are less likely than others to develop powdery mildew, you should pay attention to the following:
- William Shakespeare 2000.
- Westminster.
- Cadillac.
- Crocus Rose.
- Rosaman Janon.
- Gloria Day.
- Halle.
- Hot chocolate.
And although new varieties are considered the most resistant, some bred in the last century also have high resistance to the disease.
Fungal Diseases of Roses:
White coating on the leaves and buds of roses is the first and main sign of an unpleasant fungal disease, called powdery mildew. It spreads extremely quickly and, if control measures are not taken, can literally destroy the plant.
Is there a reliable remedy for powdery mildew on roses? There is even more than one - and we will tell you about them in detail.
Signs and dangers of powdery mildew
At the end of spring, summer and even autumn, a white powdery coating may appear seemingly out of nowhere on previously healthy rose plants (both outdoor and indoor). All above-ground parts of the plant are covered with it - leaves and shoots (primarily young ones), buds and even thorns.
This “powder” can be easily wiped off even with a finger, so inexperienced flower growers may not attach any significance to an incomprehensible phenomenon. But in vain - after a few days, the plaque will appear in the same place again, greatly increasing in size and capturing more and more areas, because this is a sign of powdery mildew, which can quickly destroy both the infected plant itself and neighboring crops.
Not only roses suffer from this disease. The fungus also actively affects many other garden and vegetable plants - pear and apple trees, zucchini and beets, currants and gooseberries, grapes and strawberries, cabbage and cucumbers.
The most vulnerable to the fungus that causes powdery mildew are hybrid tea and remontant roses.
Fungal white plaque on roses most often develops in conditions of poor lighting and dense rose bushes, poor soil aeration, sharp fluctuations in temperature and humidity of air and soil, excess nitrogen fertilizers and lack of calcium in the substrate. All this leads to impaired immunity, weakening of plants and, as a consequence, to the appearance of powdery mildew.
How to get rid of powdery mildew on roses
The fight against powdery mildew on roses begins with prevention - it is easier to prevent any disease than to get rid of it for a long time and painfully.
As you already know, the development of fungus is facilitated by dense plantings, excessive dampness, excess nitrogen and calcium deficiency in the soil. Therefore, your plants initially need to create suitable conditions:
- Choose rose varieties that are resistant to powdery mildew ( Cadillac, Rosoman Janon, Westminster, Gloria Day, Aphrodite, Crocus Rose, Halle, Summerson, Hot Chocolate, Purple Tiger, Four You's Love etc.).
- Plant roses in well-drained soil and in areas with adequate light.
- Do not allow plantings to thicken.
- Remove and destroy plant debris and litter in a timely manner.
- Water the bushes only in the morning (this helps the water on the leaves dry out during the day) and only after the top layer of soil has dried.
- Apply the recommended rates mineral fertilizers, especially nitrogen ones - it is better to underfeed the plant than to overfeed it. An acceptable option is to replace mineral fertilizers with organic ones (compost, diluted chicken manure).
- Dust roses with ash two or three times a season.
- For preventive purposes, spray rose bushes with Fitosporin.
But what to do if you neglected prevention, didn’t take care of the plants, and a white coating has already appeared on the roses?
First, trim and destroy absolutely all affected parts of the plant. It is also advisable to tear off the old large leaves below that touch the ground, and thin out the shrub roses.
Second, adjust your watering schedule to get rid of excess moisture. In a greenhouse, for example, ventilation and heating systems need to be optimized.
Thirdly, if possible, you should replace the top layer of soil in the container (for indoor roses) or under the plant in the area to get rid of accumulations of mushroom mycelium.
How to treat roses against powdery mildew? At the first signs of disease, treat the bushes with 1% Bordeaux mixture or 0.4% copper oxychloride solution. In case of severe infection, carry out abundant therapeutic spraying of plants and the soil under them with a fungicide (Topaz, Fundazol, Acrobat MC, Previkur, Skor, Bravo, Racurs) two or three times with an interval of 7-10 days.
While fighting powdery mildew, avoid using any fertilizers.
Folk remedies for powdery mildew on roses
If you fundamentally do not want to “poison” your garden with “chemicals,” you can try treating roses against powdery mildew with folk remedies. Just remember that the vast majority of them are effective only as a preventive measure or in the initial stages of the spread of the disease. If the fungus “operates” on the bushes for more than a week, fighting powdery mildew in this way is practically useless. It may be possible to stop the development of the disease, but not completely eliminate it.
So, how to treat roses from white plaque? Folk remedies from powdery mildew:
- Soda solution. 1 tbsp. baking soda or soda ash and 1/2 tsp. liquid soap is diluted in 4 liters of warm water. The solution is cooled and used for spraying roses (2-3 times in dry weather at intervals of a week).
- Ash infusion. 1 kg of ash is poured into 10 liters of warm water, left for 3-5 days, stirring regularly, filtered, added 1/2 tsp. liquid soap and used to spray roses. You can add another 10 liters of water to the ash sludge and use this solution for irrigation.
- Mustard solution. 2 tbsp. dry mustard diluted in 10 liters hot water, cool and use both for spraying roses and for watering them.
- Garlic infusion. 30 g of chopped garlic is poured into 1 liter of water and left for 24 hours. Then filter and use for spraying.
- Potassium permanganate solution. 3 g of potassium permanganate powder is diluted in 10 liters of water. The solution is used both for spraying roses and for watering them.
- Whey solution. 1 liter of whey is diluted in 10 liters of water. The solution is used for spraying.
- Infusion of rotted manure. Rotted cow manure is diluted with water in a ratio of 1:3 and left for 3 days. Dilute the resulting concentrate twice with water and spray the bushes.
- Horsetail decoction. 100 g of crushed fresh plant is poured into 1 liter of water, left for 24 hours, and then boiled for 1 hour. The broth is filtered, cooled, diluted with water in a concentration of 1:5 and sprayed on rose bushes. This concentrate can be stored for no more than a week in a cool, dry place.
Downy mildew (peronosporosis) on roses
In addition to powdery mildew itself, rose gardeners may also encounter so-called downy mildew, which is caused by completely different fungi. This disease is scientifically called downy mildew and appears as discolored spots (yellowish, red-brown or purple) on the upper side of the leaves. At the same time, brownish-grayish spots with a powdery coating may form on their lower side. Then a yellow border appears at the spots, after which the leaves darken, dry out and fall off. Usually, downy mildew damage to a rose begins from the top of the bush.
Among roses, flowers of hybrid tea varieties are most susceptible to downy mildew. Among ornamental plants Gloxinia, carnation, viola, forget-me-not, zinnia, chrysanthemum, hydrangea, etc. are at risk.
Fungal spores of the pathogen overwinter in plant debris and soil. And in spring, summer and autumn, spores are helped to spread by wind, heavy dew, precipitation, insects, as well as contaminated garden tools. The most favorable conditions for the development of peronosporosis are cool, damp weather with drizzling rains, as well as heavy acidic soils.
Prevention and treatment of downy mildew are identical to those in the case of rose disease with powdery mildew (see above).
Proper agricultural technology and timely preventive measures - important conditions in the fight against powdery mildew of roses. Do not forget to give your plants enough time so that they delight you with lush blooms year after year.
When beautiful flowers bloom in the garden, you must agree, it’s nice, but if something happens to the flowers, your mood deteriorates. Often a white coating appears on rose leaves or buds and you don’t always understand what to do, how to treat, what to treat. And in this article I will try to answer in as much detail as possible all the exciting questions about this unpleasant matter.
Why does a white coating appear on the leaves and buds of roses?
There may be several reasons for the appearance of white plaque on roses:
- Powdery mildew (downy mildew);
- Gray rot;
- Pests (spider mites, roseate scale insects, roseate leafhoppers, etc.)
Most often, roses are affected by powdery mildew. Powdery mildew can be real or false. Next we will talk about how they differ and what symptoms they have.
Causes of powdery mildew:
- Excess nitrogen fertilizers;
- High humidity;
- Dry soil around roots;
- Dense planting of rose seedlings;
- High air temperature.
Symptoms of powdery mildew
At the initial stage, a grayish (closer to white) coating appears on the leaves in the form of spots on both sides of the leaf (bottom and top). Gradually the leaves curl, dry out and fall off. The shoots take on a curved shape, flowering stops, and the plant begins to lag in growth. As a result, the rose loses its attractive appearance.
Unfortunately, powdery mildew is quite difficult to treat, therefore, it is better to carry out prevention and choose resistant varieties. Resistant varieties include roses with hard, shiny foliage, but roses with soft, matte leaves are more susceptible to this disease.
How to treat roses for powdery mildew
If a white coating on the leaves of roses appears due to this disease, then the sooner you start the fight, the greater the chance of saving the plant. In the initial stages, you need to remove all diseased leaves, shoots, or buds and burn them.
Next, spray the plant with horsetail infusion: pour 1 kg. fresh herbs or 150 grams of dry water in a bucket and let it brew for a day. After a day, the infusion should be boiled for 30 minutes, allowed to cool and strain. Store the prepared solution in a plastic container. Before use, it is diluted with water 1:5.
You can treat a sick plant with nettle infusion. The infusion is prepared from 1 kg. fresh nettle (or 200 grams of dried) and 5 liters of water. Leave to infuse for 2 weeks, stirring the solution daily. When fermentation begins, add a little drill flour to the solution (to reduce the smell). The finished infusion is filtered and diluted in water 1:10.
You can also prepare a solution of 2 parts ground sulfur and 1 part lime. Pollinate roses with this solution in warm, dry weather. Before treatment, the rose is sprayed with warm, clean water.
A copper-soap solution, prepared from 300 grams of laundry soap (grate) and 9 liters of hot water, helps to cope with powdery mildew. Soap is dissolved in water. Copper sulfate is diluted with water in a separate container (30 g per 9 liters of soap solution). copper sulfate). When copper sulfate is diluted in a small amount of water, it is poured into the soap solution in a thin stream, stirring constantly.
The finished solution is allowed to cool and the roses are sprayed.
You can also treat the rose with colloidal sulfur (dilute 100 grams of sulfur in 10 liters of water).
Downy mildew
Symptoms of downy mildew
Unlike true powdery mildew, with this disease a white coating appears on the leaves of the rose from the bottom of the leaf. This plaque looks more like mold. Over time, the white coating changes color to brown or red, and the leaves become deformed.
What to do
It is important to see the disease at the initial stage, since at the beginning of the disease the plant can still be saved by removing the affected parts of the plant and burning them.
If the disease was not noticed immediately and it has spread to most of the rose, then the plant must be destroyed.
If you can’t bring yourself to destroy your favorite rose, you can try to save it. To do this, you can use preparations that contain copper (Bordeaux mixture, copper sulfate, copper soap solution, etc.). Spray the plant at least three times at intervals of 10 days. For prevention, you can spray other roses that are nearby.
The causative agent of gray rot is fungi that appear in winter on the remains of the plant (if you do not completely remove the foliage from the roses before covering them).
Conditions for the occurrence of gray rot:
- Excess nitrogen in the soil;
- Wet and cool weather;
- Dense landing.
Symptoms of gray rot
Light appears on the rose (leaves, buds and shoots). gray plaque along with brown, rotting spots. After some time, the affected leaves turn yellow and fall off.
What to do
As always, the best control measure is prevention. Try to regularly loosen the soil around the roses and apply fertilizers that enhance oxidative processes that prevent the development of fungi (these are manganese-containing fertilizers).
- If the disease does appear, then in the initial stages remove all diseased parts of the plant and try to create drier conditions (do not overwater the roses)
- Traditional medicine suggests using horsetail infusion in the fight against gray mold (I mentioned above how to prepare it).
- If the disease has already spread to most of the plant, then it is treated with a solution of foundationazole.
- If the disease is advanced, you can use a solution of Bordeaux mixture.
The rose scale insect is a small brown sucking insect covered with a white shield. Affects leaves and old branches.
Symptoms
Scale insects live in colonies. When a plant is infected with scale insects, small white plaques similar to dandruff appear on the leaves (on the underside). With severe damage, the plant is completely covered with a white coating and over time the affected areas turn yellow and die.
What to do
The scale insects themselves are not dangerous and can be easily gotten rid of, but they can cause more serious fungal diseases. Therefore, it is necessary to immediately take measures to combat these insects.
- At the initial stage, insects are simply removed from the affected parts of the plant using a cloth or toothbrush. After the scale insects have been removed, the affected areas are lubricated with a solution of garlic, soap and water (1:1:3) and left for a day, and then washed off. In this way, the plant is treated until the scale insects completely disappear (the interval between treatments is 7 - 10 days).
- You can also spray the plant with a solution of soap and kerosene (40 grams of laundry soap are dissolved in 1 liter of water and 5 drops of kerosene are added).
- The affected areas can also be lubricated with alcohol or vodka.
“Unfortunately, if the plant is severely affected, then it is almost impossible to fight the scale insects”
Spider mites also love roses, but when they appear on the leaves and buds of the rose, it is not a white coating that appears, but a cobweb. I won’t talk about spider mites here, since I wrote about them in more detail earlier ().
To protect roses from various diseases, you can plant plants next to them that repel harmful insects. It is also advisable to do everything possible to attract beneficial insects, amphibians and birds that feed on harmful insects to your garden.
For example, the ladybug and its larvae, which eat pests, help to cope with scale insects and spider mites. Ladybug lays larvae near pest colonies. When voracious babies emerge from the larvae, they happily eat their enemies.
To attract beneficial insects to your roses, try to plant plants with nectar (mustard, dill, etc.) nearby.
White spots on rose bushes can appear for various reasons. In order to understand what to do with the plants, you need to find out the root cause of the anomaly. Very often it lies in the defeat of the bush various diseases and insects:
Rose leafhopper or scale insects, spider mites, etc. can also be associated with white spots.
Of all the possible diseases, roses often suffer from powdery mildew. This disease has two forms: real and false. The present form of the disease develops as a result of improper care:
- rare watering;
- high humidity;
- excessive fertilization of bushes with nitrogen fertilizers;
- dense planting of plants;
- high temperature.
In addition to powdery mildew, roses become covered with white spots when they are affected by gray rot. Plaque appears as a result of the activity of a fungal pathogen. For the development of this pathology, cool and humid weather is needed, as well as a high nitrogen content in the soil. Dense planting of rose seedlings also leads to the appearance of gray rot.
Main symptoms and dangers
Stains white cover the leaves, stems and rosettes of plants, giving them an unaesthetic appearance. Regardless of the reason why the white coating appears, the plants will suffer. If you don’t start treating them and normalize them proper care, roses may die. Therefore, if your beauty is covered with a white coating, you need to act immediately. And the type of action depends on the cause that caused the pathology. To effectively cure plants, you need to identify the disease by its symptoms. To do this, you need to familiarize yourself with the white coating in more detail in order to identify the differences between gray rot and powdery mildew.
Powdery mildew has the following symptoms:
- the plaque that appears on the bush develops on the leaves, stems and buds;
- at first it has a grayish tint;
- after a while, the infected leaves begin to curl, the shoots become deformed, and flowering stops;
- spots appear on both sides of the sheet;
- pathology develops in late summer or early spring.
Downy mildew has the following symptoms:
- spots appear on the bottom of the leaf;
- outwardly they look like mold;
- over time they become red or brown;
- leaf deformation occurs.
With gray rot, the entire bush is also covered with spots. Here the color of the lesion has a gray tint. Over time, the stains begin to rot. At the next stage, the affected leaves begin to fall off.
Once the disease has been identified, you need to figure out how to treat infected roses.
Plant treatment
To cure plants affected by fungi, they should be treated with special solutions. Moreover, the choice of remedy depends on the pathogen.
If the bushes are affected by powdery mildew, they can only be saved if the treatment is carried out at an early stage of the disease. First, remove all infected shoots, leaves and flowers. All plant debris must be burned to prevent the pathogen from spreading to other garden crops. After this, the bushes are sprayed with horsetail infusion. You can also use nettle to prepare the solution. Often, to combat powdery mildew, a solution of ground sulfur diluted in lime (2:1 ratio) is used. A copper-soap solution is also quite effective.
Remember: in order for the use of a healing solution to give the desired result, you must strictly follow the instructions for its preparation, otherwise the disease will not be defeated.
When bushes are affected by downy mildew, it is also necessary to first remove all infected areas from the plants. If the disease was not identified immediately and has already affected the entire bush, all that remains is to destroy the rose. Such plants can no longer be treated even with the use of strong remedies.
In case of minor damage to bushes by powdery mildew, an effective means of combating the disease will be spraying with preparations that contain copper. In this case, roses can be treated with Bordeaux mixture, soap-copper solution, copper sulfate, etc. For 100% destruction of pathogenic microflora, plants should be sprayed at least three times. 10 days should pass between treatments. For preventive purposes, it is recommended to spray all plants that are adjacent to the affected roses.
Some gardeners note the effectiveness of a solution of potassium permanganate for the destruction of downy mildew.
In case of infection of bushes with gray mold, horsetail tincture is often effective. In case of severe damage, you should use a solution of Fundazol or Bordeaux mixture.
To prevent the disease from appearing in the future, the bushes are periodically sprayed with agents that prevent the development of the diseases described above. Additionally, as a preventive measure, you should periodically loosen the soil, as well as use fertilizers that inhibit the development of fungi.
Knowing what the white coating on the stems and leaves of a rose is, you can quickly and effectively cure the bush from the scourge that has struck it.
Bordeaux mixture is used on roses for various spots and rust.
Powdery mildew on roses is a common fungal disease that covers plants with a white coating, causing deformation and drying out of the buds. Initially, the coating appears delicate and cobwebby, and then it becomes powdery. The appearance of the plaque varies depending on the characteristics of the rose variety and climate (a mosaic color or thickness may appear on the leaves). With severe damage, rose leaves curl, turn brown, dry out, and fall off prematurely. The bare branches of roses are completely covered with a brownish felt coating. Rose shoots stop growing, bend, thicken, turn red and die. By autumn, the mycelium turns brown and becomes covered with small black dots.
The reasons for the appearance and spread of powdery mildew are: diseased seedlings (the mycelium of the fungus overwinters in the buds), inconsistency of existing growing conditions with the requirements of roses, as well as the lack of prevention and timely measures to protect plants at the first signs of the disease. Roses are especially susceptible to powdery mildew when high humidity air in warm and hot weather.
To prevent the appearance of powdery mildew, weeds in the rose garden are destroyed, plant residues are carefully collected around the rose bushes and their subsequent destruction, and the soil is dug deep in the fall.
Traditionally, rose bushes affected by powdery mildew are sprayed with foundationazole or colloidsulfur. Mullein infusion also helps. The soil around diseased bushes can be treated with the preparations “Maxim”, “Fitosporin-M”, and foundationol.
In autumn, rose bushes are sprayed with a 0.3% solution of copper oxychloride; in the spring - a 0.5% solution of copper oxychloride or a solution of copper sulfate with soap and soda (15 g of copper sulfate, 200-300 g of green soap, 50 g of soda ash).
