Roses are one of the most popular garden plants and are called the queens of flowers for a reason. You've probably invested a lot of time and effort into caring for it, so it's all the more annoying if you suddenly notice some kind of problem with your beloved plant. In addition to aphids, a particular fungal disease is a common plague - powdery mildew on roses. Do you suspect that your rose bush has just been infected? We explain how you can recognize the fungal infection and what you can do about it to save your plant - without any harmful chemicals!
Powdery mildew or downy mildew on roses – what’s the difference?
With boththese are fungal diseases, however, they differ in their characteristics and the causes for their development are also different.
Powdery mildewforms a coating on the leaves that is silvery to gray in color. The fungus also deforms the tips of the shoots. It occurs primarily when there are larger temperature fluctuations and, more precisely, when temperatures are warm during the day but fall more sharply at night, which creates dew. And it is precisely this moisture that the fungus likes. ThePowdery mildewis also the one most likely to attack roses.
Downy mildewOn the other hand, it is characterized by yellow-colored leaves, and a grayish coating appears on the underside, which is reminiscent of mold (not to be confused with another disease - gray mold). This variant is also caused by the combination of warm and humid, but these two conditions occur at the same time. So if it's nice and warm outside and there's rain on top of that, those are the perfect conditions. This also happens quickly in greenhouses.
What helps preventatively?
It is therefore only logical that the best preventive measure is to avoid the environments described above. That starts with thatcorrect location, which should meet the requirements of the rose. Oneoptimal ventilationAllowing moisture to dry quickly is another important factor. When it comes to roses, it is important to avoid mulching with bark mulch, as this promotes fungal growth. Planting under other, lower plants is the better choice here, as this also guarantees good ventilation. When fertilizing, do not overuse the nitrogen. It promotes the formation of many new leaves, which in turn also increases the susceptibility to powdery mildew.
But what if it's already too late? What helps with powdery mildew on roses and can save the bushes as quickly as possible? This mainly depends on the type:
Fight powdery mildew fungus
As already mentioned, the actual fungal infection is on the shoot tips and buds. The fungus can also overwinter there without any problems, so the low winter temperatures will not help you. Instead, it comes to youPruning the rosesHelp in the spring by disposing of the cut shoots (in the trash or burned). But you should take action against even the slightest infestation before it spreads further. Home remedies are then effective. If these don't work, resort to commercial remedies. There is also a sufficient selection there that is not harmful to the environment.
Fight downy mildew fungus
In this case, the fungus attacks the leaves. As soon as the rose bush has shed its leaves in autumn/early winter, you take action. You should dispose of this immediately (in the trash or burn it) to prevent the fungal spores from spreading further and to rid the already infected plant of them. If you notice a fungal infestation again in the coming year, you can resort to home remedies. If these do not have the desired effect, use environmentally friendly products from retailers.
Home remedies for mildew on roses
Natural remedies for mildew on roses are not 100 percent effective, but can be a good method for mild infestations, i.e. in the initial phase and as a preventive measure. The following might be helpful:
- Milchis effective both for existing powdery mildew and as a preventive measure. Mix raw milk or whole milk with water in a ratio of 1:8 and spray the rose bushes with this solution. It is important that you do not take long-life milk, as it no longer contains the lactic acid bacteria required and would therefore not be effective.
- Loosen a packagebaking powderin two liters of water and add 20 ml of rapeseed oil. Spray sick plants as well as healthy ones for prevention. The treatment should be repeated especially after rain, as this washes the product off. The alkaline reaction that disrupts the fungus is effective in this home remedy. Remember here too that the effect is relatively weak and only works for light infestations.
- Algae limehas a high pH that prevents spores from multiplying. So if you are looking for a remedy for fungal diseases that is harmless, this is ideal. A powder sprayer is best suited to finely distribute the lime onto all leaves and plant parts. However, before you diligently use the product on all your plants, keep in mind that plants that require acidic soil and are sensitive to too much lime cannot tolerate it.
