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Black spots on the leaves of a rose, like other lesions, cause weakening and reduce the budding of the plant. If measures are not taken in time to eliminate the disease, the flower may die. It can be very problematic to combat spotting, it often happens that it spreads to all bushes. Experienced gardeners argue that it is much more effective and easier not to treat already infected roses, but to prevent this disease annually.
What does black spot look like and what is dangerous?
Brown spot on rose bushes is caused by the fungus Marssonina rosae, which is transmitted by rain or dew drops and has a detrimental effect on the crop.
The disease does not appear immediately, the leaves of roses begin to become covered with black spots 30 days after the development of the fungus. The only exception to this rule is humid, warm weather. At temperatures around 30 degrees, spotting can become noticeable as early as the tenth day. But usually it manifests itself fully closer to July.
The first symptoms appear at the bottom of the plant and gradually spread to the top of the bush. Shoots and leaves are covered with dark brown spots with a yellow border. Over time, other symptoms appear:
- the spots begin to grow, acquire a black color;
- the leaves turn yellow and curl, a little later they begin to crumble;
- shoots grow slowly or stop developing altogether;
- buds become inconspicuous in appearance or completely cease to form on the bushes.
Black spot is difficult to treat and can completely kill the plant.
Why did black spots appear on the leaves of a rose, and they fall
In order for the treatment of the disease to give a positive result, it is important to correctly determine the reason why black spots appeared on the roses, and they shed their leaves. There are several reasons contributing to the defeat of the bushes:
- Damp and warm weather. Leads to the activation of fungal spores, as a result of which the leaves of the roses begin to become covered with brown spots and fall off.
- Inappropriate landing site. A thickened area or lowland contributes to the slow evaporation of moisture, reproduction and spread of spotting.
- Improper care. Untimely detection of provoking factors can also be the cause of the onset of the disease.
- Using too little or too little fertilizer. Lack or excess of nutrients leads to the development of the disease.
What to do and how to treat black spots on rose leaves
Timely and correctly selected treatment of black spot on roses (see the photo of the lesion below) will help get rid of the disease. There are several ways to combat the disease, but the first thing to do is cut and burn all diseased leaves. If this procedure is neglected, then in the new season the rose will get sick again.
In addition to destroying the diseased elements of the plant, gardeners often resort to the use of various means, which are also considered very effective in the fight against black spot. Preparations can be of both chemical and biological nature, some use folk methods.
The foliage of a rose with black spots must be cut off and burned
Chemicals
If the leaves of the rose turn yellow, become covered with black spots, then they should be treated with chemicals, which contain mancozeb and zinc. The most effective among them are:
- Oksihom.
- Profit M (Profit M).
- Copper chloroxide (Cloroxed cuprum).
- Ridomil gold.
- Strobe.
Treatment should be carried out every 14 days, constantly changing the drug. This is done so that the fungus does not develop strong immunity to it.
Treatment of the disease should be carried out until the dark spots stop growing and spreading.
Biological agents
If yellow leaves with black spots are found on a rose, you can use not only chemical, but also biological agents to eliminate the problem. The drug Fitosporin-M with the addition of Zircon or Siliplant has proven itself as a cure for black spot. Before processing, all diseased specimens should be destroyed, then the soil should be fed with copper-containing compounds and the bushes should be sprayed with a solution. The procedure should be carried out every 5 days, preferably at least four times. In the intervals between treatments with "Fitosporin", you should also shed the soil around the plants.
Folk methods of struggle
You can also fight dark spots on the leaves of a rose with the help of improvised means. Spraying seedlings with iodine solution is considered a good folk method against infection. In this case, you should use the product carefully so that it does not fall on the ground. Prepare the drug by mixing 1.5 ml of iodine and half a liter of water.
Another popular antifungal agent is a decoction of onion peels. They can both spray and water a diseased plant. To prepare the medicine, take the husk of two onions and boil it in 500 ml of water.
Cow dung is no less effective against spotting. Mullein is bred in a ratio of 1 to 20 and the culture is watered with the resulting infusion.
Many gardeners report good results after using infusions of dandelion, nettle or horsetail.
Alternative methods of dealing with black spot are less effective and more suitable as preventive measures.
How to treat roses from black spot in spring
To avoid the appearance of black spots on the leaves of roses, they should be sprayed in the spring, before bud break. Copper sulphate is considered by many gardeners to be the most common and proven primary treatment. It is a very powerful fungicide and is only allowed to be used once a season. Diluted in a proportion of 50 g per 1000 ml.
Towards the end of spring, in May, you can additionally spray roses with Strobi. This should be done 2-3 times with an interval of 10 days.
How to treat roses from black spot in summer
A cheap remedy "Fitosporin M" can help to avoid black spot on roses. Regularity is considered only the main rule when using it. Biofungicide will give results if it is used throughout the summer period, every week (especially in August). Its combination with Gumi paste can increase the effectiveness of Fitosporin.
How to treat roses from black spot in autumn
For successful wintering, rose bushes are also important to treat with anti-infection agents. You can improve them both with folk methods (onion broth, iodine solution) and with purchased preparations (fungicides).
In autumn, the treatment of roses from black spot consists in the use of "Fitosporin" (if the plant is not diseased). Spraying should be carried out with the onset of cold nights, fog and dew. The frequency of actions is up to 4 times, every 5 days.
At the slightest suspicion of black spot infection, rose leaves should be sprayed with stronger drugs, such as:
- Topaz (topazius).
- Speed (skor).
- Bayleton
If the disease covers the entire bush, then it is better to use "Hom" or "Oxyhom".
Prevention of the onset of the disease
As preventive measures to combat black spot, gardeners use the same means as in the treatment of an ailment. The only difference between the procedure is the frequency of use of the drugs.
Timely processing of the plant
Spraying must be carried out even before the appearance of black spots on the leaves and on the rose bush, at the time of the onset of warm weather, after the snow melts. At this time, the mushrooms do not have time to get stronger and spread. For prevention, fungicides, biofungicides and formulations with copper are usually used:
- Glyocladin or Mikosan-I (100 ml per 10 liters of water).
- Copper sulfate.
- Bayleton.
The first spraying of roses from black spot should be carried out in early spring.
Planting Disease Resistant Varieties
There are no varieties that are 100% immune to rose disease - black spot. But as practice shows, the species with glossy leaves are considered the most resistant to damage:
- Grand Amore (Grande Amore).
- Quadra.
- Leonardo da Vinci (Leonardo de Vinci).
- Resonance (Resonanz).
- Nostalgie.
- Baroness (Baronesse).
Climbing varieties, as well as tea and polyanthus varieties, are more prone to infection with black spot. It is worth refraining from planting such roses if the growing conditions are conducive to the onset of the disease.
Recommendations
So that brown spots on the leaves of roses never appear, it is advisable to follow these recommendations:
- Change drugs constantly... Both the treatment of roses and the measures for the prevention of black spot should be carried out with different substances. The fungus is good at adapting to life and can develop resistance to fungicides.
- Consider the harmfulness of the composition... When purchasing a drug, you should pay attention to its hazard class and strictly follow the recommendations for the preparation of solutions.
- Burn affected leaves... The fungus is completely destroyed only after exposure to fire, no other methods have any effect on it.
- Carry out prevention... Every spring, you should well spray the leaves and bushes of roses with antifungal drugs, monitor the evaporation of moisture from the ground, observe the interval between plants when planting.
- Plant only healthy seedlings... You need to buy cuttings of roses strong and uninfected, preferably in specialized stores. Before planting new bushes, it is better to try to keep them in quarantine for 1-2 months.
Conclusion
Black spots on the leaves of a rose can not always provoke the death of a plant. To avoid sad consequences, it is important to diagnose the disease in time and take urgent measures to eliminate it. And it is better not to neglect preventive measures, regularly provide the shrub with proper care and not allow the development of black spot at all. If infection occurs, treatment will take a long time.
