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Petunia is a flower with a huge variety of varieties and bright colors. Many gardeners willingly plant this unpretentious and ornamental plant in flower beds, and decorate balconies and verandas with hanging flower pots. The flower's immunity is very good, but it is not completely immune from diseases. Powdery mildew on petunia is one of the most typical diseases for the plant.
What does powdery mildew look like on petunias?
As you can easily understand from the photo of powdery mildew on petunia, the name of the disease quite accurately characterizes how the flower looks shortly after infection. First, a powdery whitish or grayish coating, reminiscent of spilled flour or powdered sugar, appears on the leaves. Then it spreads to the stems, buds, flowers, covering the entire plant. The plaque gradually turns into drops of cloudy mucus, reminiscent of dewdrops.
Powdery mildew is a pathogen that can attack most garden crops.
The pathogenic fungus that causes powdery mildew parasitizes petunia, penetrating the cells and feeding on its juices.This disrupts the processes of photosynthesis and metabolism; after only 3-4 days, if nothing is done, the tissues affected by it turn yellow, the leaves dry out and fall off. The growth rate of the flower slows down sharply. Very few new buds appear; they are small and deformed. Without the necessary treatment, the plant completely dries out and dies in 1.5-2 weeks.
There is another pathogen with similar external signs of infection - downy mildew. It can be distinguished by a more fluffy coating, similar not to powder, but to lint. It appears only on leaves and stems, without affecting buds and flowers.
Downy mildew on petunia is no less dangerous than real powdery mildew
Reasons for appearance
Of the petunia diseases, powdery mildew is one of the most common. Pathogenic fungi that provoke its development most often live in the soil. Under unsuitable conditions, they do not manifest themselves in any way, but if the air temperature drops to 16-18 ºС and the humidity rises to 60-80%, they become more active. Other factors contributing to the development of powdery mildew:
- planting in deep shade (lack of sunlight);
- excessive use of nitrogen-containing fertilizers;
- dense plantings in the flowerbed (as a consequence - the impossibility of ventilation);
- non-compliance with the recommended schedule and watering norms (the substrate is moistened too often and/or abundantly).
The pathogen enters the flower tissue through the lowest leaves, often lying on the ground. Also, spores of the pathogenic fungus are carried by rainwater, wind, and insects; the infection is transmitted from infected plants to healthy ones through direct contact.The gardener himself can “participate” in this, transferring pathogens on his hands and/or clothes, equipment in the process of caring for the flowerbed.
Neglecting disinfection of garden tools and tools is a big mistake.
How to deal with powdery mildew on petunia
There is a large arsenal of products that help get rid of powdery mildew on petunias. These are both traditional methods and chemicals. To stop the spread of the fungus, you need to use a clean, disinfected tool to cut off all parts of the plant that show symptoms, capturing an additional 3-5 mm of healthy tissue, and remove the top 2-3 cm of soil from the flowerbed, replacing it with fresh, disinfected substrate.
Treatment with drugs
Chemicals are the “heavy artillery” for treating powdery mildew on petunias. They are used if the disease was not noticed at an early stage, and the process of its development has already gone quite far.
Fundazol
A universal fungicide that helps to cope with most pathogenic fungi that affect garden crops. Treatment is effective even if the infection process has already progressed. The drug remains in the tissues of petunia for another 2-3 weeks, this is an effective prevention of re-infection for a plant with a weakened immune system.
To prepare a working solution, 1 g of Fundazol is diluted in a teaspoon of water at room temperature. When the fungicide is completely dissolved, add more water, bringing the total volume to a liter. Thoroughly spray the petunias with the prepared product and spill the soil in the flowerbed.
To completely destroy powdery mildew, carry out 2-3 treatments every 3-4 days.
Amistar-Extra
A remedy that allows you not only to get rid of powdery mildew, but also to help petunia recover from the disease. The drug stimulates metabolism at the cellular level, prolongs the growing season, and increases the flower's resistance to adverse weather and climatic conditions.
The working solution is prepared by diluting the chemical with water in a ratio of 1:10. It begins to act within an hour after treatment.
After a single spraying of petunias and soil, the protective effect lasts for 15-20 days
Topsin-M
A complex drug that helps get rid of many pathogenic fungi. To treat petunias, 1 ml of fungicide is diluted in a liter of water. The solution begins to act on the same day.
The drug supports plant immunity, stimulates photosynthesis
Score
A contact universal preparation suitable for preventing the appearance of powdery mildew on petunias and for combating the disease. Its effect begins within 2-2.5 hours after spraying and watering the plants; the chemical prevents the mycelium of the pathogenic fungus from spreading in the tissues and receiving the necessary nutrition. The working solution is 2 ml of the product diluted in 10 liters of water.
Carry out 2-3 treatments with an interval of 15-20 days
Folk methods of struggle
Folk remedies give the desired effect only if the disease is noticed at the initial stage of development. They can also be used for prevention.
What gardeners use:
- Copper sulfate. Proportion – 1 g per liter of water. Treatments are carried out 2-3 times every 7-10 days.
- Potassium permanganate. Petunias are sprayed with a dark pink solution (2-3 g per 10 liters of water) every 4-5 days. Enough 3-4 times.
- Baking or soda ashA. 10 g per liter of hot water is enough. Stir the soda well. Petunias are treated with a solution cooled to 37 degrees 3-4 times weekly.
- Whey or kefir. Dilute with water 1:10. Plants are sprayed 4-5 times with an interval of 1.5 weeks.
- Garlic (teeth or arrows). “Raw materials” (about 50 g) are finely chopped, poured with a liter of water, and left for 24 hours. Strain before use. Petunias are sprayed 4-5 times weekly.
- Mustard powder. Proportion – 50 g per 10 liters of hot water. The infusion is ready for use after 4-5 hours. 2-3 treatments every 4-6 days are enough.
Potassium permanganate is an affordable disinfectant whose effectiveness has long been tested and proven.
Prevention
Instead of treating powdery mildew on petunias, it is better to take preventive measures. They are quite simple, first of all, this is compliance with agricultural technology:
- Planting plants according to the recommended scheme. The dimensions of petunia bushes vary depending on the variety, the minimum interval between them is 25 cm.
- Timely and correct watering. The soil should be allowed to dry 5-7 cm deep.
- Application of nitrogen fertilizers at the beginning of the active growing season, when petunias are increasing their green mass, and in the required proportions. Excess nitrogen negatively affects the plant's immunity.
- Regular removal of faded buds and dry leaves.
If petunias are planted too densely, powdery mildew spreads very quickly.
Also, to prevent powdery mildew, you can spray petunias with biofungicides (Fitosporin, Fitolavin) or infusions every 15-20 days:
- Wood ash (3 liters) is poured into 10 liters of boiling water and left for 5-7 days. Strain before use.
- Onion peel. For 10 liters of water take 200 g of raw materials. The infusion is ready in 2-3 days.
Conclusion
Powdery mildew on petunia is a disease that affects almost all garden crops. The best prevention in this case is proper care. If, upon discovering a problem, nothing is done, a harmless whitish coating can quickly destroy the plantings in the flowerbed.
