Powdery mildew on roses how to get rid of

Powdery mildew on roses

Powdery mildew, popularly known as ashstone for a long time, is a widespread disease that affects a wide variety of plant crops. If the first signs of infection are ignored, the plant can suffer serious damage, expressed in the loss of its flowering and productive qualities. In severe cases, this disease can lead to the death of the affected plant.

Roses are among the crops at risk of powdery mildew infection. A dangerous ailment can destroy the exquisite beauty of these popular gardening plants, which are present in almost every summer cottage and in rural front gardens. In order to protect the "queen of flowers" from infection with ashtrays, it is necessary to take certain preventive measures, as well as follow agrotechnical recommendations for caring for it. In this article, we will talk about how to diagnose powdery mildew disease in a timely manner, what measures to take to cure it, and how to protect roses from this danger.

Powdery mildew on roses: short

Powdery mildew on roses

The most popular opinion is that the disease with powdery mildew was first recorded in Europe at the very beginning of the 20th century, more precisely in 1907, and penetrated the continent in the 19th century, being brought from America. However, there is reason to believe that this disease has a much older history and has already visited European coastal areas. It happened back in ancient times, in the 4th century. BC. Ancient Roman sources mention a plant ailment whose symptoms are remarkably similar to those of powdery mildew. One way or another, this disease is not only dangerous, but also extremely common, capable of affecting vast territories.

A variety of plant crops fall into the risk group: it can be vegetables, cereals, fruit trees and shrubs, ornamental plants.

The source of powdery mildew infection is erysiphoid fungi, also called powdery mildew. These include various species that affect, respectively, a particular culture. As for roses, the fungus Sphaerotheca pannosa Lew.var.rosae Voron is dangerous for them - it is he who is the causative agent of powdery mildew that affects representatives of the Pink family.

Infection with powdery mildew leads to the loss of their decorative qualities by roses: the growth and development of all parts of the plant slows down, the buds and leaves are deformed. Flowering may not start at all, or with a noticeable delay, the flowers will be very few in number and also deformed. Fruiting on such plants will also be threatened. The foliage also bears a sign of the disease - it gradually turns black and dries up, later the leaves fall off. The end result may be the death of the plant, since the disease with powdery mildew lowers its immunity. Weakened plants are unable to resist other diseases, adverse weather conditions and can become easy prey for pests. Winter cold, as a rule, they cannot withstand.

Of all the varieties of roses, the varieties of the remontant and tea-hybrid groups are most at risk of being affected by powdery mildew.

Powdery mildew on roses: causes and symptoms of the disease

Powdery mildew on roses

There are many reasons for infection with this dangerous fungal disease.The most common are the following:

- non-fulfillment or incorrect implementation of agrotechnical recommendations regarding a given plant crop;

- planting low-quality material that already carries the spores of the fungus;

- too dense arrangement of rose bushes on the site;

- too frequent and plentiful application of nitrogenous fertilizing;

- lack of nutrition against the background of a deficiency of such vital elements as potassium and phosphorus;

- lack of preventive measures;

- the presence of weeds in the territory allocated for the rosearium;

- lack of air circulation in the soil, which may be due to its density and the refusal to loosen the soil around the rose bushes.

The factors that increase the risk of powdery mildew infection are high temperatures and high humidity. Already at 22-24 degrees of heat and humidity above 60%, favorable conditions are created for the development of a fungal infection. The daily temperature drops characteristic of the Russian middle zone also contribute to the spread of the disease.

Spores of the fungus are carried by wind and water, roaming from one rose bush to another - which is why it is important to observe the recommended interval between planting holes. With direct contact of an infected plant with a healthy specimen, infection is almost inevitable. Spores of the fungus persist in the winter on plant debris and weeds - therefore, rare weeding and the lack of measures for cleaning the site at the end of the season directly affects the risk of powdery mildew infection. With the arrival of spring, the overwintered pathogens move to rose bushes weakened after the winter cold.

The process of infection most often starts at the beginning of June - the spores of the fungus begin to act in full force, first capture the lower leaves of the plant, gradually rising up and affecting all its parts.

Powdery mildew on roses has rather vivid symptoms that distinguish it from other fungal diseases of plant crops. First of all, they include a whitish bloom, which in fact is nothing more than a spider web. Its similarity in color to flour was the reason why the disease began to be called powdery mildew. In the process of maturation of the spores, the surface of the foliage begins to be covered with droplets of liquid, similar to morning dew - this also explains the origin of the name of the disease. Towards the end of August, these "dewdrops" darken, acquiring a brown tint. The leaves and stems of plants are covered with dark beads - this means that a new generation of spores has formed and will continue to spread the disease over time.

Prevention of powdery mildew disease

Of course, it is much easier and safer for a plant to prevent infection and the development of a disease than to subsequently fight it using chemicals. Therefore, timely and competent measures to prevent powdery mildew damage play an important role in growing roses. There are quite a few ways to protect rose bushes from a dangerous fungal disease:

- first of all, it is necessary to regularly inspect the plants in order to detect the first signs of the disease in time;

- recommendations for planting rose seedlings in the ground are also of great importance - these are drainage work, and the observance of the intervals between planting holes, and the correct lighting regime on the site, and its sufficient openness, provided that it is well protected from blowing through the wind;

- regular weeding will remove possible spore carriers from the site - weeds;

- the necessary agrotechnical procedures include systematic watering of the beds;

- we should also not forget about the rules for fertilization - an excess of nitrogen, coupled with a deficiency of potassium-phosphorus fertilizers, can significantly increase the risk of the disease;

- when choosing fertilizers, it is recommended to give preference to organic matter - yeast solutions, compost, manure and poultry droppings, herbal infusions, solutions based on wood ash;

- spraying with protective mixtures will also protect roses from fungus;

- at the end of the season, it is necessary to clear the area with rose bushes from plant residues in which spores of the fungus can hibernate;

- in the autumn period, it is shown digging the earth around the rose bushes.

It should also be borne in mind that there are a number of varieties of roses specially bred by breeding that have increased resistance to powdery mildew disease. Such persistent varieties are present in different groups of roses, whether it is climbing roses, scrubs, ground covers or floribundas.

Here we will name the varieties that are recognized as the most resistant to infection with this dangerous disease. So, the top 5 varieties that most successfully resist fungal disease:

- Variety "Leonardo da Vinci" is known for its luxurious double flowers of deep pink color and unpretentious character, which allows it to withstand not only fungal attacks, but also adverse weather conditions;

- “Wedding Bells” hybrid tea pearlescent pink flowers are an enviable exception among their group products, especially those suffering from powdery mildew;

- “New Dawn” is another persistent variety, distinguished by its versatility and enjoying the well-deserved fame of the “rose of the world” due to its wonderful silvery pink flowers and unpretentious character;

- Velvet roses of the "William Shakespeare 2000" variety are regarded by many growers as favorites among red roses;

- The variety of climbing roses "Rosarium Uetersen" has recently received well-deserved recognition, although it was bred back in 1977 - at the moment it is the most resistant climber to diseases.

Spraying of rose bushes is of great importance in the prevention of powdery mildew - usually they are carried out in spring and autumn. For this purpose, copper-based preparations are used, such as Bordeaux liquid, copper sulfate solution. Their effectiveness is significantly increased by adding soap to them - as a rule, ordinary household soap. One of the recommended recipes for such a mixture includes 15 g of copper sulfate, 200-300 g of shavings of laundry soap or liquid green, 50 g of soda.

Ready-made preparations are also suitable for spraying: 0.25% Benomil solution, 0.4% Cineba solution and 0.1% Fundazol solution. It is recommended to spray the rose bushes in the spring before the leaves appear or in the fall after they have fallen off. The procedure can be repeated every 2 weeks.

Another preventive measure is the introduction of foliar-type dressings in the period on the eve of the opening of the buds. A good choice would be a mixture of 0.3% superphosphate solution with 0.3% potassium nitrate solution.

Fighting powdery mildew on roses using folk methods

With the appearance of the first symptoms of powdery mildew damage to the rose, it is recommended not to rush to the use of chemicals. It is highly likely that folk remedies that do not harm the plant will help to defeat the disease. Below we list the most popular remedies:

- Mix 1 liter of whey with 10 liters of water and add 10 drops of iodine solution. Spray rose bushes twice with a break for a week, maximum - 10 days.

- Dissolve 50 g of baking soda and 40 g of soap shavings in 10 liters of water. Treat the bushes twice with an interval of 7 days.

- Pour 1/3 of a bucket of fresh manure with 10 liters of water and leave for 3 days, stirring regularly. Dilute the mixture filtered through gauze with water in a ratio of 1:10.

- Pour ½ bucket of finely chopped garden weed with hot water (1 bucket), leave for 2 days, stirring. Strain through cheesecloth before use. The use of coltsfoot, dandelion, celandine, plantain is recommended as raw materials.

- 80 g of chopped garlic, pour 10 liters of water, bring to a boil. The solution can be used for spraying only cold and strained.

The spraying procedure requires compliance with certain rules:

- it is recommended to take care of personal protective equipment in advance, since even herbal infusions, if they get on the mucous membranes of the eyes and respiratory tract, can cause allergic reactions;

- the ideal time for spraying is the evening, when the risk of burning roses is minimal;

- only fresh solutions and infusions are suitable for spraying, they cannot be stored;

- the minimum is double spraying, then - until the symptoms of the disease disappear completely;

- before starting spraying, it is necessary to cut off all leaves, buds and flowers affected by powdery mildew from the bush, and then burn them.

The use of chemicals during treatment

In especially difficult cases, when folk remedies have not had a sufficient effect, it is inevitable to turn to chemicals. These include fungicides specially formulated to kill fungal pathogens and treat the effects of fungal infections.

Today, specialized stores have a wide range of environmentally friendly biofungicides and systemic drugs.

The latter include "Fundazol", "Quadris", "Skor", which are the most popular among gardeners. No less effective are Fundazim, Baktofit, Maxim and Topaz.

The use of biofungicides is becoming more and more widespread, since these preparations are based on natural materials and do not harm the plants themselves and the environment. Their disadvantage is a short duration of action and lower efficiency in comparison with chemical agents. Therefore, they will have to be used more often, the consumption of such drugs will be higher. Biofungicides include Fitosporin-M, Planriz, Alirin-M and Gamair. All recommendations for use indicated on the packaging with biofungicides or chemical fungicides must be observed. General recommendations are as follows:

- the interval between spraying should be at least 2 weeks;

- the best time for processing is evening;

- it is not recommended to use the same drug all the time - mushrooms develop immunity to its action and then do not react to processing, therefore, fungicides must be applied alternately;

- personal protective equipment is especially important when working with chemicals - you will need a protective suit, goggles and a mask, or a respirator;

- for spraying, it is best to choose a dry, windless day - this eliminates the possibility of chemicals getting into the human respiratory tract, and also guarantees a longer action of the product, since rain can wash off the treatment coating.

Powdery mildew infection is a serious problem faced by many summer residents and gardeners. Owners of rose bushes are no exception, because powdery mildew can cause irreparable damage to the decorative qualities of flowers and even destroy the entire plant. The recommendations listed in this article for the protection, prevention and treatment of this dangerous disease will help prevent the infection of roses, or cure the affected plants as effectively as possible. For these purposes, both ready-made preparations, which can be purchased in specialized stores, and folk methods of dealing with powdery mildew are suitable. The most popular recipes and drugs have also been listed above.