If we have a rose bush in our garden, it is possible that it is attacked by some pests or diseases. Powdery mildew is one of the most frequent and serious diseases that can attack your rose. It is usually recognized by the naked eye as a white powder that appears on the leaves, stems and flower buds. The powdery mildew of the rose bush must be stopped in time so that it does not destroy the entire plant. It is often called ash or white because of its symptoms. The cause of this disease are fungi of the genus Podosphaera that begin to settle on plants and cause considerable damage.
For this reason, we are going to dedicate this article to tell you everything you need to know about roseate powdery mildew, what its main symptoms are and how to eliminate it.
Symptoms of rosebush powdery mildew
The first symptoms of rose bush powdery mildew are almost imperceptible red blisters on the surface of rose leaves, followed by powdery white spots on the ground of the plant. The fungus can infect any part of the plant, but it prefers young tissues, and it is the most tender buds and flower buds that usually show the first signs of disease.
When the fungus occupies the bushes, the leaves are deformed and the ability of the plant to photosynthesize is reduced. The buds are not open and the growth of the rose bush is affected. Serious infections can prevent the growth of leaves that fall early and reduce flowering. If allowed to develop, the fungus will continue to spread and cover the entire plant until all of its leaves die.
A variant of Sphaerotheca pannosa . The rose, also known as Podosphaera pannosa , is the most common rose powdery mildew species and the cause of this disease in rose bushes . The spores germinate on the surface of the leaf, where the mycelium grows and branches into plant cells for nourishment. On the surface, the formation of new spores continues, invading other areas of the plant.
The spores are spread to new plants by wind currents. When bad weather arrives, to survive in adverse conditions, the fungus can remain dormant in the soil on the buds or under the bushes. The most active period of powdery mildew of the rose bush begins in spring, when the weather begins to warm, and lasts all summer and even part of autumn . Like almost all mushrooms, poor ventilation and high humidity promote growth.
Control of powdery mildew on rosebush
This fungus usually exists in the substrate, waiting for favorable conditions to infect the garden plants. To prevent and combat it, proper hygiene must be followed. We are going to see some good practices to be able to reduce and control powdery mildew on the rose bush:
- Clean and dispose of fallen leaves and other debris around the base of the plant.
- Prune the infected part of the plant and dispose of it properly.
- Provide enough water and nutrients to the rose bushes to maintain their defense capabilities.
- Keep rugs to prevent moisture loss.
- Leave enough room for the rose bushes to provide good air circulation.
- Prune and clean the center of the shrub so it is well ventilated indoors.
- Water the roses in the morning to quickly dry the leaves and prevent infection by pathogenic fungi.
- You can use some fungicides that serve as a preventive measure . During the conditions of the year where they are more optimal for the growth of powdery mildew on the rose bush (this is usually spring and autumn since rainfall and warmer temperatures join) you can read the product label and follow the instructions to prevent the appearance of powdery mildew. .
Some natural treatments against powdery mildew of the rose bush
There are some unconventional chemical control methods that provide alternative modes of action for commercial synthetic fungicides. The most effective household methods for controlling rose powdery mildew are Epson’s milk, sulfur, potassium bicarbonate, salt, and oil.
- The Epson salt must be used regularly during the season.
- Sulfur can prevent spores from germinating, so it must be applied before disease occurs.
- Copper sulfate is an effective fungicide allowed in organic agriculture.
- The neem oil effectively neutralizes powdery mildew in many plants to interfere with the metabolism of fungi and spore production stop.
- Mixing sulfur with fish oil and / or sesame oil is also effective.
- Milk is a very popular fungicide, diluted with water and sprayed on sensitive plants at the first signs of infection. The exact mechanism of action is unclear, but the known effect is that ferroglobulin (a type of whey protein) generates free oxygen radicals when exposed to sunlight, and contact with these free radicals is harmful to fungi. .
- Baking soda and water-soluble mineral or vegetable oil sprays are also recommended to control powdery mildew, although these mixtures have limited and inconsistent effects. The high concentration of sodium is harmful to plants.
Environmental conditions
To keep these types of diseases at bay and take good care of the rose bush, we are going to recommend some environmental factors to take into account:
- When planting, it should be remembered that most rose bushes prefer sunny, well-ventilated places, but not affected by strong winds. Only for certain varieties and very hot climates, semi-shade is recommended.
- Rose bushes grow best in slightly acidic soils rich in clay and silt. If the substrate has these characteristics, you can avoid plant defects and health problems in the future.
- The soil must have a good drainage to avoid suffocation of the roots, the rose bushes are very sensitive to the roots. However, the earth must always maintain a certain humidity. This is especially important for potted rose bushes.
- It should be watered on the substrate , not on the leaves to avoid the appearance of fungi.
I hope that with this information you can learn more about rose powdery mildew and how to eliminate it.
