How to get rid of powdery mildew on roses using only folk remedies

The appearance of a characteristic whitish coating on rose bush leaves is a sign of powdery mildew, which can quickly significantly degrade the appearance of a rose garden, interfere with flowering, and even cause the death of the plants. The disease progresses quickly, and gardeners have no more than a week to stop the infestation with minimal impact on the rose plantation.

Causes of powdery mildew

The disease is caused by a group of fungi, various species of which parasitize garden, cereal, fruit, and ornamental crops. In roses, the disease is caused by the species Sphaerotheca pannosa.

The fungus overwinters in cracks in the bark or in the buds of rose bushes, and in the summer it spreads to other plants by spores or conidia, which are carried by wind, water, or indirect contact with an infected plant (through hands, garden tools).

Factors contributing to the disease:

• growing in low light conditions;
• sudden temperature changes;
• high humidity (sometimes 65% is enough to activate the fungus);
• warm weather (the pathogen requires an air temperature of 22°C);
• dense planting of rose bushes;
• excess nitrogen in the soil;
• deficiency of phosphorus, potassium and calcium in plants;
• oxygen starvation of roots.

The most vulnerable to powdery mildew are remontant roses and their descendants – hybrid tea varieties.

Symptoms and consequences of the disease

In the central zone, symptoms of the disease on rose bushes are most likely to be detected between mid-July and early September, but cases of fungal awakening have often been noted as early as the end of May.

Fungal infestation usually begins on the lower leaves and gradually spreads to the upper tiers of the bush. A powdery, grayish-white coating appears on the leaves, shoots, thorns, and sometimes even on the rosebuds. This is a cluster of fungi that feed on the sap of the upper tissues of the plant. Over time, droplets of liquid appear on the coated leaves, and the coating turns brown.

The fungus not only damages the surface tissues of the affected areas of the bush, but the coating on the leaves also disrupts photosynthesis, which, if the infestation is extensive, affects the overall health of the plant. Leaves become deformed, eventually turning black, drying up, and falling off. Damaged buds fall off without opening. Rose bushes lose their decorative appearance especially quickly if the fungus attacks the shoots.

Control measures

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Treating roses for powdery mildew should begin at the first sign of the disease. First, remove and burn any damaged leaves, buds, flower stalks, and shoots, then treat the bushes with an antifungal agent. In the early stages of the disease, folk remedies are quite effective, but later, only chemical treatments can save the rose plantation.

Folk remedies for treating roses

Spray the bushes until the symptoms of the disease disappear, but at least twice. This should be done in the evening to prevent droplets on the leaves from causing sunburn, but before dark. When treating the plants, don't spray them; instead, thoroughly wet the leaves (including the undersides) and branches to ensure water runs off the bush.

The best remedies for powdery mildew on roses:

• Copper sulfate. A powerful fungicide. First, prepare a solution of 5 g of copper sulfate and 250 ml of water (the substance dissolves best in water at about 40-50°C). In another container, dissolve 50 g of finely ground laundry soap in 5 liters of water. The solution will be more effective if you use green soap, but you will need more – about 600-900 g. Pour both solutions into one container and mix thoroughly. It is recommended to spray the bushes once a week for two months.
• Wood ash. Pour 1 kg of ash into a bucket of warm water and let it steep for 1 week. Strain the resulting infusion; for better adhesion to the leaves, it is recommended to add a little soap to the solution. Apply the ash infusion to rose bushes once a week until the problem has healed. For preventative purposes, the product can be applied every 2 weeks for an indefinite period.
• Baking soda. Dissolve 20-25 grams of baking soda in 5 liters of hot water and add 20 grams of laundry soap to the solution. You can use baking soda, but washing soda will produce better results. After the solution has cooled, you can spray the bushes with it. Spray three times, every 10 days.

• Garlic. Crush or chop 80 g of garlic cloves, pour 10 liters of cold water over them, and let sit for 24 hours. Spray the strained solution once a week until the plants recover, or throughout the summer (as a preventative measure).
• Milk whey. To treat rose bushes, dilute the whey with water 1:10. It is recommended to add 1 drop of iodine per liter of solution. Apply the whey three times over a period of 7 days, but do not add iodine to the solution prepared for the final treatment.
• Potassium permanganate. You'll need a 0.025% solution (2.5 g of potassium permanganate per bucket). Spray three times, with five-day intervals between applications.
• Mustard. Add 2 tablespoons of mustard powder to a bucket of warm water and stir thoroughly until dissolved. Apply the solution to rose bushes every two weeks during the summer. While spraying the above-ground parts with the mustard solution, you can water the plants at the same frequency.
• Manure. Fill a bucket one-third full with rotted cow manure and top it up with water. Let it sit for three days, then strain and dilute with water 1:2. Fresh manure can be used, but in this case, dilute the product with water 1:10. Leave 14 days between sprays.
• Horsetail decoction. To prepare the remedy, take fresh green parts of the plant, chop them, add water (1 liter per 100 g of raw material), and let steep for 24 hours. Then, boil the infusion for 1.5-2 hours. After cooling, strain the liquid. Immediately before use, dilute one part of the decoction with 5 parts water. Spray the affected bushes with the decoction 3-4 times, every 5 days.
• Onion peel. Pour 200 g of the peel into 10 liters of water and let it steep for 24 hours, then strain. It's best to dissolve soap in the finished product at a rate of 1 g per liter of the infusion. Spray the roses three times, 10 days apart.
• Green infusion. Pour 10 liters of hot water over half a bucket of freshly chopped herbs (nettle, celandine, plantain, dandelion) and stir. Let steep for 2 days, strain before using.

All products should not be stored; they must be prepared before use.

Tips on agricultural practices to combat powdery mildew

In addition to treatments, it is necessary to adjust plant care to create conditions unfavorable for the fungus.

During treatment it is recommended:

• promptly cut off diseased leaves (shoots, buds) from the bush and burn them;
• remove all old leaves from the lower tier, especially those that touch the ground;
• reduce the number of waterings – give water only after the top layer of soil has dried out;
• do not irrigate plants using the sprinkler method;
• do not feed roses;
• replace the top layer of soil in the flower bed.

Prevention

 

Regular preventative measures can help prevent rose bushes from becoming infected with powdery mildew and some other fungi. Proper agricultural practices and preventative treatments can help prevent the disease.

Rules for growing roses:

1. Avoid planting too densely. The distance between rose bushes should correspond to the variety's requirements.
2. Choose sunny areas with daytime light for planting roses.
3. When growing on heavy clay soils, loosen the soil before planting (add sand, sawdust) to improve its aeration qualities.
4. Regularly loosen the soil to provide the roots with oxygen.
5. Do not allow the flower bed to become overgrown with weeds.
6. Don't neglect autumn cleaning: collect and burn fallen leaves, dig deep into the soil under the roses.
7. Provide plants with the necessary fertilizers, but do not allow excess nitrogen fertilizers.
8. Disinfect garden tools. A 1% copper sulfate solution works well for this purpose.
9. Inspect roses regularly, detecting fungus or pests early on. Pay particular attention to the lower parts of the bushes.

Selecting a variety

There are rose varieties that are resistant to powdery mildew and a number of other common fungal diseases:

• "Sommersonne";
• William Shakespeare 2000;
• Westminster;
• "Rosarium Utersen";
• "Germany";
• New Dawn;
• "Hot chocolate";
• "Aphrodite";
• "Rozaman Janon";
• Schloss Ippenburg;
• "Wedding Bells";
• Cadillac;
• Purple Tiger;
• "Leonardo da Vinci";
• "Rozaman Janon";
• "Halle".

Preventive spraying

Any folk remedies can be used for preventative treatment against powdery mildew. Copper sulfate is considered the most effective. Additionally, in the spring (before flowering) and fall (after leaf fall), it is recommended to treat rose bushes with Fundazol (10 g per 10 liters) or Zineb (40 g per 10 liters).

To support plants during difficult periods when they are most vulnerable to fungus (after flowering, replanting, and after winter), foliar feeding with phosphorus and calcium is recommended. For this, the bushes are sprayed with solutions of superphosphate and calcium nitrate. Prepare and apply both solutions separately, without mixing (30 g of each per 10 liters).

Like other fungi, powdery mildew primarily appears in weakened plants that are not properly cared for. Risk factors include unsuccessful overwintering or transplanting, pest infestations, and other diseases. The fungus very rarely attacks strong, healthy plants. Therefore, the most effective preventative measure is establishing an optimal care regimen for the crop, taking into account the needs of the specific variety.