Combat powdery mildew on roses

There are a variety of measures that help to remove the white coating on the rose petals. However, it is also helpful to ensure in advance that this plant disease does not break out in the first place.

Different types of powdery mildew

Anyone who notices powdery mildew on their roses should definitely take a close look. Because there are two different types of this fungal infestation, which is also called fair weather fungus. However, both variants spread via spores, which form a dense network of very fine fibers on the plant. Experts also call this mycelium.

Both the so-called "powdery mildew" and the "

downy mildew“ A white to gray fur forms on the roses, which is particularly visible on the upper side of the leaves. This can simply be wiped off with a damp cloth. However, if the infestation is already more pronounced, the buds and the shoot tips are usually also affected and crippled. The leaves of affected rose plants appear bumpy and brown at the tips. This stops the growth of the roses.

Rapid spread under special climatic conditions

Powdery mildew on roses is particularly evident in phases of fine, dry weather, which is accompanied by nightly dew. It is therefore clear that sunny days in spring and autumn in particular create the ideal living conditions for this fungal infestation. If nothing is done to control this pest until late autumn, dark winter fruiting bodies will form, which can hibernate in leaves and plant debris on the ground.

Downy mildew is not always clearly recognizable

In contrast to the whitish coating of powdery mildew, downy mildew mainly forms reddish-purple spots on the upper side of rose leaves. There may be yellow and brown spots on the leaves, bordered by leaf veins. On the other hand, a gray fungal coating forms on the underside of the leaves, which is soft to the touch. Infestation with downy mildew can go so far that rose buds and shoots are also attacked.

In contrast to the warm and dry conditions that powdery mildew needs to grow, downy mildew spreads primarily in humid and only moderately warm climates. Excessive nitrogen content in the soil of the plant also contributes to infestation with this pest. If you want to protect yourself against powdery mildew when you buy your rose plants, you should make sure that the plant is declared “against breeds 1 – 26”. This means that the roses are immune to certain subspecies of the fungus, which are constantly developing new resistances.

Combat mildew with simple home remedies

It is important to many garden owners and plant lovers to protect their garden from chemicals in pesticides. If you then worry because your roses are infected with mildew, you can use simple home remedies to counteract this:

• Above all, milk has proven itself here, with fresh milk being used in particular.
• You simply mix one part milk with nine parts water and spray this mixture on the infested plants at close range.
• The microorganisms contained in the milk are usually very successful in fighting the fungal infestation, which also makes it clear why it has to be fresh milk and why UHT milk is not suitable for use.
• The lecithin contained in the milk works against mildew and the sodium phosphate strengthens the rose plant's defenses.
• This achieves two important results with a relatively simple measure that should be carried out about two to three times a week if necessary.

Further precautions are recommended

In general, the natural resistance of the rose plant offers the best protection against fungal attack. There are already many varieties that show a low susceptibility to pests such as powdery mildew, especially in bed and shrub roses, but also in ground-covering varieties. Those who prefer hybrid teas and hybrid teas should know that these genera Resistance breeding is still in its infancy and the garden owner is therefore entitled to individual measures are meeting Generally recommended:

• regular removal of plant debris
• Separation of infested plant parts and safe disposal
• Clean garden tools or growth aids meticulously, preferably with an antiseptic
• always wear gloves when treating diseased roses
• only apply chemical pesticides directly to the diseased rose

Prevention is better than treat

As in many other areas, the principle that prevention is more effective than the best pesticide afterwards applies to the healthy and beautiful growth of roses in the garden. You can already take precautions when choosing the plants by carefully considering the soil and sun conditions at the planting site.

In addition to regular care and fertilization, the plants should also be pruned regularly, as this is a promotional measure for the health and growth of the plant and does not look nearly as radical as a plant cut that removes diseased or infested parts of the plant should. The rose, in particular, recovers only very slowly and with great difficulty.

Harmful infestations such as powdery mildew can be prevented with individual care tips and by observing rose growth and blossom development. This not only saves time and money for fighting, but also enables the rose to have a long, healthy life, which is rewarded with magnificent flowers in all their blaze of colour.

Worth knowing about rose powdery mildew shortly

• Powdery mildew is a collective term for various plant diseases caused by fungi.
• It usually occurs through a white coating, the so-called mushroom lawn, on the leaf surfaces.

A distinction is made between the genuine and the false mildew: The powdery mildew pathogen belongs to the sac fungi and mainly affects leaves. First, the leaves are covered with a mealy coating and later turn brown until they dry up and fall off. The downy mildew belongs to the monofungi and penetrates into the plant. It is indicated by a white coating on the underside of the leaves.

• In agriculture and horticulture, fungicides with a chemical structure are used to combat the various types of powdery mildew.
• The powdery mildew is usually associated with a crop protection products based on sulphur.

For example, while powdery mildew is harmful to plants, an intact ecosystem needs powdery mildew for some ladybug species. The sixteen-spotted, twenty-two-spotted, and sixteen-spotted ladybirds feed exclusively on powdery mildew, making this plant disease vital to these species.

In German gardens, roses in particular are affected by powdery mildew. Very sensitive varieties of roses can be severely weakened by this disease. The fungal spores are spread by the wind and need moist leaves to germinate. The formation of dew at night is usually sufficient for this.

• To prevent mildew infestation, one should roses only plant in a moist and nutrient-rich soil in a sunny position.
• The soil should be particularly rich in potassium, as this strengthens the immune system roses.
• Furthermore, susceptible roses should be as bright as possible and watered little.
• You should support them plants with fertilizer strengthen and repot into a fresh container.
• The leaves should be kept dry and thus protected from rain.

An old home remedy for powdery mildew is baking soda and oil mixed together and dusted on the plant. Mix three packs of baking soda with 50ml of cooking oil and add a few dashes of washing-up liquid as an emulsifier and spray endangered plants with it every ten to fourteen days in the evening. The mealy coating quickly disappears and what still looks damaged after a few days can simply be cut out.

Basically you need a lot of patience to fight powdery mildew, although you shouldn't wait too long in the event of an infestation, because the rose will quickly weaken and wither.

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