Content
A white coating on the leaves of a rose indicates damage by pests or diseases. The symptom is characteristic of all varieties - climbing, hybrid, park, peony, bush. To restore the plant, it is necessary to make a diagnosis and choose the right medicine. Therefore, it is worth considering each case separately.
Why do rose leaves turn white?
A common reason why rose leaves suddenly turn white is decreased immunity. In turn, this leads to the spread of fungal infections and rot, the symptoms of which are expressed in the appearance of a whitish coating.
Powdery mildew
The disease affects the stems, flowers and leaves of roses. The fungus multiplies in spring or summer. It may appear in the fall due to violation of agrotechnical standards: uneven watering, dense planting, lack of minerals.
The disease affects roses when the soil is poorly loosened, which is a common problem among beginners.
Powdery mildew is spread by insects, animals and wind. Outdoor plants often suffer from this. When processing indoor plantings, you cannot work with equipment located outside the house. It may also contain fungal spores. Therefore, it is advisable to store garden tools indoors or regularly disinfect them.
The fungus overwinters in the bark of plants, under the shoots. When external conditions become favorable again, microorganisms become active and begin searching for a viable plant. As a result of the lesion, a white coating appears.
It can be easily removed with your finger, like dust. Owners are accustomed to not paying attention to the symptom. Because of this, photosynthesis processes slow down and roses stop developing. The white coating gradually grows, moving to new shoots. Nearby plantings also suffer.
Downy mildew
Downy mildew appears as a white coating on the leaves and buds of roses. The fungus that causes it prefers hot weather with high humidity levels. Occurs after summer rains.
More often, plaque on the leaves due to downy mildew has a yellowish tint.
Unlike “true” powdery mildew, the white powder is more difficult to notice because it is located on the back of the leaves. If the plant is outdoors, it makes sense to conduct a daily inspection. Subsequently, the rose shoots lose chlorophyll and become brown or red.
Gray rot
It is a microscopic fungus. To survive the cold season, it hides in green vegetation. Gray mold occurs in areas with a high nitrogen content.
Favorable conditions are cloudy weather, dense planting, high humidity
Symptoms indicating damage: white plaque on leaves, flowers, stems. It has a velvety texture.
Pests
Insects pose a threat to many crops. They cause the formation of brown, gray or white plaque on the leaves and stems of roses. Pests eat the plant, leaving behind only veins. Because of this, immunity decreases, and fungi are given complete “carte blanche.”
Most pests become active during the growing season, that is, in the spring. Some prefer green vegetation, others prefer roots. The appearance of a brown coating indicates infestation with thrips, a winged insect about 13 mm in size. Thrips are agile and difficult to catch.
The adult parasite is black in color, the body of the young one is covered with greenish or brown color.
It is difficult to distinguish the larvae, especially with the naked eye. They are very small and well hidden by the parent. They don't have wings. Otherwise the signs are similar to those of adults.
The parasite is dangerous because it feeds on plant sap. It contains all the elements necessary for life. The leaves of the rose become covered with spots, and in some places you can discern the cobwebs left by the pest after mating.
The second dangerous insect, after which a white coating appears on the leaves, is the scale insect. It can affect both outdoor and indoor roses.Externally, the scale insect resembles a simple beetle.
The parasite has an elongated body 5 mm long, painted white or brown.
The first symptom of scale insects is a decrease in growth rates. Then a slimy coating and red spots appear on the roses.
What to do if rose leaves are covered with a white coating
You need to choose a treatment method based on the cause of the appearance of white plaque. There are several methods of struggle. The most popular were folk and chemical ones.
Folk remedies
In the early stages of powdery mildew, you can use folk remedies. To do this, infected areas are sprayed with Bordeaux mixture. The lower leaves in contact with the ground are removed to avoid damage. In case of dense planting, try to ventilate the plants more often. Watering is also carefully controlled; there should not be excess moisture.
The recovery process takes some time. At the same time, the culture is under stress. In order not to bring the bush to this state, it is recommended to follow preventive measures. These include regular pruning of the lower leaves and weeding.
Downy mildew is difficult to treat. The easiest way is to burn the affected part of the bush. If the rose is completely infected, it is sprayed with chemicals. In case of a small lesion, treat with Bordeaux mixture.
Copper sulfate, used twice a week, shows good results.
Gray rot is not dangerous in the early stages.To restore roses from white coating on the leaves, it is enough to reconsider agricultural practices. It is necessary to create a high-quality drainage system, monitor moisture levels and control lighting. Abundant watering is carried out in case of prolonged drying of the soil. In other situations, they rarely moisturize.
They start using chemical drugs only if folk remedies have not helped. Infusions are prepared from horsetail with the addition of soap. Baking soda has an excellent effect.
To combat pests, prepare a bucket of water and 100 g of laundry soap. The solution is applied to each sheet, even if there is no white coating on it. Complex fertilizers are not applied so as not to attract other parasites. Nitrogen is the first thing to be eliminated.
Chemicals
Chemistry gives quick results, but is toxic. This is the only drawback of the method. To treat white plaque, the drug Topaz and Skor are used. They are effective against powdery mildew.
In order not to harm the roses, follow the instructions; each preparation is individual.
Fundazol will help restore the crop from downy mildew.
Fundazol has a complex effect, strengthens the immune system, kills fungi and harmful bacteria
Attention! It is better to alternate chemistry with traditional recipes. This way the owner will ensure a speedy recovery of the roses.
Thrips are controlled using the drug Decis.
If the store does not have Decis, Actellik or Karbofos should be nearby on the counter - they are no less effective
The substances are combined to prevent the insect from developing immunity. The white coating on the leaves caused by scale insects is removed with the chemical Actellik.
Prevention of white plaque on roses
By adhering to preventive measures, you reduce the risk of white plaque appearing on rose leaves. If the disease occurs in the initial stages, they will help restore the plant. Such measures include:
- Moderate application of fertilizers, regular watering. Such procedures strengthen the immune system. It becomes easier for roses to survive insect attacks; they cease to be afraid of fungi. Even when infected, the bush resists, buying time for the gardener.
- Check daily for symptoms. It is easier to cope with diseases in the early stages, when microorganisms have not had time to settle. When a white coating appears, act immediately. Plantings are treated with folk and chemical means.
- Removal of hazardous vegetation in the autumn season. With the onset of cold weather, parasites begin to look for places for the upcoming winter. They are leaves, bark, weeds and all living things that lie on the ground. When the temperature becomes favorable again, the larvae and spores will wake up with an insatiable hunger.
Conclusion
White bloom on rose leaves poses a threat to further development. The owner needs to determine the cause of the disease and take immediate action. The problem is dealt with using folk or chemical drugs. However, experienced gardeners recommend using all available methods.
