In summer, most ornamental plants are subject to fungal infection - powdery mildew; On roses and other flowers, the disease manifests itself as a white coating on the leaves. With further spread, the fungus affects the stems and buds. To protect plants, you should find out the cause of the disease, and also choose the most suitable control method.
Causes of the disease
Powdery mildew manifests itself most clearly on roses; measures to combat the disease depend on the reasons that provoked the fungal infection. Risk factors include:
- increased air humidity;
- over- or under-watering;
- a large amount of precipitation;
- high concentration of nitrogen in the soil;
- insufficient exposure to sunlight;
- the bushes are too close to each other.
Infection of roses occurs when a favorable environment for the growth of the fungus is created, and this is, first of all, dampness. Therefore, for effective treatment and prevention of re-infection, care should be adjusted and comfortable conditions for the life of the plant should be provided.
Signs of disease
It is quite easy to recognize the disease. It is not like other types of fungal infections. Its characteristic features include:
- The appearance of plaque on the leaf plate. Young shoots on which the fungus settles in the form of a white powder are more susceptible to infection.
- Spots on leaves. Reddish-purple spots and ulcers may appear on the leaf blade.
- Pustules on the stem. The mycelium of the fungus is localized on the stem of the rose in the form of small growths. As the disease develops, the pustules increase in area and density.
- Plant growth stops.
- Deformation and falling of leaves.
The leaves closest to the ground are affected first. In advanced forms of the disease, plaque spreads to the stems and buds. The leaves become deformed and do not return to their shape even after treatment with drugs.
A white coating covers the leaf blade, thereby creating an obstacle to photosynthesis. As a result, the plant does not receive the necessary nutrients and looks lifeless.
An equally common disease of roses, which has similar symptoms, is downy mildew. But there are some differences in its manifestation. Instead of a white coating, red-brown or purple spots appear on young leaves, and mature leaves lighten and acquire a gray tint. In this case, a dense layer similar to a cobweb is formed on the back side of the plate. These symptoms are often associated with acid rain or sunburn. This disease should be treated with a solution of boric acid (5 grams per 5 liters of water).
Methods for treating powdery mildew on flowers
You can get rid of powdery mildew on roses using special chemicals and folk remedies. It should be noted that the disease develops rapidly. Within two weeks, the plant may be completely covered with powdery mildew. Therefore, at the first signs of infection, it is necessary to take disinfection measures.
Chemicals
Fungicides are presented in a wide variety of contact and systemic agents. Contact fungicides are characterized by the destruction of fungus upon external contact with it. Systemic drugs penetrate the plant tissue and poison the sap, which has a detrimental effect on the causative agent of the disease.
Many gardeners use antibiotics such as streptomycin and penicillin to treat powdery mildew on roses. But experts do not consider this method effective, since antibiotics are not able to destroy the fungus. Their action is more effective in fighting viruses.
Treatment with chemicals involves a certain procedure:
- Remove all affected parts of the stem from the rose. Remove fallen leaves from the ground.
- Spraying should be done in calm weather, in the morning or evening.
- Carefully treat the bush with the preparation, wetting the leaves on both the top and bottom sides.
- Indoor roses can be completely dipped into the prepared solution. You should also treat the walls of the pot and tray.
- To improve the effect, systemic and contact fungicides should be alternated.
- When spraying, be sure to cultivate the ground around the bush.
This algorithm of actions is also applicable to indoor roses. They are treated with the same drugs that are used for street bushes.
Fundazol
The drug must be diluted in the proportion of 5 grams of product per 5 liters of water. When processing, 1.5 liters of solution are consumed per 10 square meters of planting area. Fundazol is used at the first signs of damage to roses. Repeated treatment should be carried out after 2 weeks.
Topaz
Systemic fungicide Topaz should be diluted at the rate of 1 milliliter of the drug per 2.5 liters of water. The solution consumption during treatment is 1.5 liters per 10 square meters. Roses are re-treated after 2 weeks. Topaz can also be used for preventative spraying.
Score
The fungicide has both contact and systemic effects. To prepare the solution, you need to dilute 1 milliliter of the product in 5 liters of warm water. The prepared solution is distributed at the rate of 1 liter per 10 square meters of plantings. If necessary, treatment should be repeated after 10-14 days. Suitable for treatment and prevention.
Important! To prevent the fungus from becoming accustomed to the drug, you should not use one fungicide more than three times in a row.
Folk remedies
In addition to chemical exposure, powdery mildew can be eliminated using folk remedies.
Whey solution
Add 10 drops of iodine to the serum diluted with water (1:10). Roses are processed before noon. You can repeat the procedure after 10 days. In addition to disinfection, the serum helps saturate the plant with micronutrients.
Soap and soda solution
The spraying composition is made based on baking soda and laundry soap. Dissolve 2 tablespoons of soda in 5 liters of water. Add 1 tablespoon of soap shavings to the resulting composition. For prophylaxis, the solution is used once every 2 weeks. To treat roses, the frequency of treatments increases to 3 times a month.
You can also use soda ash. For the solution you will need to dilute 50 grams in 10 liters of water. Add 40 grams of laundry soap. Treat no more than 2 times with an interval of 7 days.
Mustard solution
Dissolve 1 tablespoon of mustard powder in 5 liters of hot water. The solution is used after cooling for surface spraying and watering.
Garlic infusion
To prepare the solution, add 25 grams of chopped garlic to 1 liter of water. The composition should infuse for 24 hours. After which it is filtered and used for its intended purpose.
Infusion of fresh manure
Fresh manure in the amount of 1/3 of a bucket is poured with 10 liters of water. They insist for 3 days. The settled water is drained, and the concentrated sediment is diluted, observing the proportions of 1:10.
Important! When using fresh manure, the proportions must be strictly observed. High concentrations may cause burns.
Prevention of the disease
To prevent roses from being affected by powdery mildew, you should follow the rules of agricultural technology.
To keep your plants healthy, you need to:
- adhere to the rules of planting and pruning;
- regularly inspect roses;
- remove weeds and fallen leaves that become a source of disease;
- keep instruments sterile when pruning roses;
- control the dosage of nitrogen-containing fertilizers;
- provide sufficient calcium and phosphorus for the plant;
- carry out preventive treatment with fungicides;
- In the fall, carefully remove the leaves around the bush and dig up the soil.
For more likely protection, it is better to choose varieties of roses that are resistant to this fungal disease.
Rose varieties resistant to powdery mildew
When purchasing roses, you should pay special attention to varieties that are resistant to powdery mildew. Thanks to the efforts of breeders, the choice of such roses is quite wide. The most popular among them:
- Purple Tiger;
- Cadillac;
- Hot chocolate;
- Rosoman Janon;
- Crocus Rose;
- Westminster;
- Gloria Day;
- Halle;
- Aphrodite.
These varieties take root well in damp climates and are suitable for both home and greenhouse cultivation.
The appearance of powdery mildew on roses is most often the result of improper care and unsuitable climate. If preventive measures are taken, the plant will delight its owner with long flowering and a healthy appearance.
