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Roses are among the eternal favorites in the garden and in your own four walls. Their characteristic flower shape, the scent, even the thorns are a real treat for anyone who takes a look at the plants. So it is not surprising that rose lovers are alarmed when suddenly a floury coating affects the leaves and the rose weakens. This is the dreaded powdery mildew, which is not to be trifled with.
mildew
powdery mildew on the leaves
When the first rose buds and leaves finally stretch out towards the light in the spring sunshine, the fear of the notorious mildew growth also increases. This forms a weakening layer on every type of rose, whether outdoors or indoors, and causes the wonderful plant to perish more and more. So that you do not lose the fight against the fungi, you should eliminate them with home remedies. It is important to know how to effectively prevent and combat the two types of mildew.
- powdery mildew
- Wrong mildew
powdery mildew
What is powdery mildew?
Powdery mildew is a disease of roses and various types of stone fruit, particularly peaches, caused by a fungus called Podosphaera pannosa. These molds have specialized in the numerous types of roses and are therefore also called the real rose dew fungus. This pathogen is one of the best-known types of mildew in the world and has been known for centuries, which is what makes treatment with a suitable home remedy so successful. Once the roses have been infected with the mycelium, it spreads like a carpet over the plants and the following symptoms appear.
powdery mildew on plant leaves
- white, mealy coating on the upper side of the leaf
- if the infestation is severe, it spreads to the underside of the leaves, shoot tips, buds and flowers
- Leaves curl up
- Flowers remain closed or do not develop due to dried up buds
- Coating can turn brownish in extreme dimensions
- Growth is curbed
- rose perished
The fungus impedes the metabolism of the roses by attaching itself to the upper side of the leaves and penetrating the cells of the plant through special suction organs. The fungus can then multiply there without any problems as long as you do not fight it. "Podosphaera pannosa" is a fair-weather fungus. As the name suggests, spore flight is more effective here as soon as it is warm and dry. Although the infestation can begin as early as spring, the powdery mildew needs temperatures of at least 20°C and alternating high humidity to become particularly dangerous. In addition, he overwinters as follows.
- forms fruiting bodies in late autumn
- these black globules contain spores
- settle on the shoot tips and buds of the rose, also in the garden foliage that has not been disposed of
- in spring the spores are distributed again when the plant sprout
This is why this fungus is so persistent and can affect different types of roses if they are not cared for properly, especially if they are weak or the location is not ideal. The rule here is: the weaker the rose, the easier it is for powdery mildew.
Wrong mildew
Downy mildew is also a fungus, but it is caused by the pathogen "Peronospora sparsa". The mold was first described in the second half of the 19th century and specializes in roses and also blackberries. In contrast to the fair-weather fungus, it is a bad-weather fungus and is therefore more effective in cooler weather conditions and shows up in spring at around 11°C. In addition, it prefers rather damp locations, as it takes advantage of the rain in spring to attack the roses. An infestation of downy mildew is broken down as follows.
- Mealy fungal growth in white-grey color on the underside of the leaf
- yellow-brown to purple spots on the upper side of the leaf
- Leaves are dropped
- affected shoots die
- Plant weakens and dies
brown and dried up rose petals
Downy mildew is much more effective than real mildew, as the spores are located directly in the plant's cells and from there they disrupt the entire nutrient balance. In doing so, they expel their organs and break through the underside of the leaf, which creates the mealy coating. It is imperative that you prevent downy mildew infection, as it is more persistent than the real thing and kills the rose plants much more quickly. This applies to both indoor and outdoor roses, although garden roses are more likely to be affected by this fungus as they use raindrops to spread.
prevent powdery mildew
If your roses have already been attacked by weather fungi, it is often quite difficult to heal them again. For this reason, you should prevent a possible infestation as much as possible. The most important thing is the correct care of the rose species, since they are only so resistant to fungi. Since rose plants are generally more demanding, you should pay attention to the following points to protect the plants from infestation.
- choose a location that has adequate air circulation, as the spores can multiply well in stuffy air conditions
- In addition, it should be very sunny, as this is the only way to dry any rain or condensation water on the leaves, which is otherwise a perfect breeding ground for the spores
- the following properties, on the other hand, are beneficial for the fungi: dark, damp, corners with poor air circulation
- Be sure to loosen up heavy soils, as they often store too much moisture and are difficult to dry
- this promotes the formation of spores and you should definitely prevent this - enrich it with potassium
- don't forget to water enough and keep the humidity high, as prolonged drought can weaken the roses
- A layer of mulch helps here, especially with garden roses, as long as the soil is permeable and humus
- do not use too many nitrogen-based fertilizers
- do not plant roses in a site previously occupied by an infested plant for four years
- the pathogens could still be in the ground and cause an infestation the next time it rains
- do not neglect the right pruning of the plant and thin out lush crowns well to avoid possible heat and air build-up
- Affected plant parts should be removed and disposed of immediately, but not in the compost
- Plant parts affected by fungi can either be disposed of in the household waste or burned - this will prevent the spores from flying
- never water in the evening as the water may not evaporate until night
- if you water them in the morning, the roses can absorb the water better and thus you do not offer a target for the pathogens
- never water the leaves or shoots, only the site itself and the roots, which like to be showered extensively
- Plant herbs among the rose plants
- Basil, chives and chervil act as a protective agent against fungi due to the active ingredients they contain
Roses in the garden bed
Maintain the following planting distances to avoid heat build-up:
- Miniature roses: 30 - 40 cm
- Bed roses: 30 - 50 cm
- Shrub roses: The planting distance corresponds to the growth height of the plant
- Climbing roses: 2 - 4 cm
- Ground cover roses: 40 - 150 cm (depending on variety)
- Dog roses: 80 - 100 cm
home remedies
Home remedies for powdery mildew
There are numerous home remedies that are suitable for combating powdery mildew of both types of fungi. The funds are especially recommended so that you don't have to resort to the chemical club. Although fungicides can be effective, they are irresponsible if you have potted plants that are then brought back indoors or have a garden that is in close proximity to neighbors or sensitive natural areas. Over the last few centuries, a number of remedies have been established with which you can easily combat powdery mildew on your roses.
- ablutions
- skimmed or raw milk, whey
- Leavening agents such as baking soda or baking soda
- herbal broths
- beneficials
ablutions
Regular washing of the rose plants is important in the event of an infestation with powdery mildew, especially if this is still in the early stages. Use a damp microfiber cloth and wipe off the plaque and then continue with one of the other home remedies. In this way you can reduce the infestation somewhat and the following remedies then move better into the plant.
powdery mildew on plant leaf
milk or whey
Skimmed and raw milk can be used quite well against an initial infestation. The contained lecithin has an aggressive effect on the spores and fights them effectively, which helps to eliminate them once and for all.
The solution:
- mix 1 liter of raw or skimmed milk with 9 liters of water
- fill the agent in a spray bottle
- treat the plants extensively with the product every two to three days
If you use whey, it does not need to be mixed and can be applied to the plant immediately. A big advantage of milk treatments are the microorganisms they contain, which not only work against the fungi, but also strengthen the defenses of the rose family.
leavening agent
Due to their properties, leavening agents such as baking powder and baking soda are also good for combating mildew.
- mix 45 g baking powder or baking soda with 50 ml rapeseed oil
- add a drop of eco-friendly washing-up liquid
- mix the remedy with five liters of water
- fill the agent in a spray bottle
- spray each affected rose with the remedy
- repeat this every three days until the infestation is eliminated
You can easily use this remedy on healthy plants. It has a preventative effect on the fungi.
Use baking soda as an all-rounder
herbal broths
Herb broths from the following plants have proven themselves extremely well against powdery mildew and also strengthen the plant from the inside.
- field horsetail
- tansy
- garlic
For the garlic broth, all you have to do is chop two cloves of garlic and add half a liter of boiling water. Wait until the brew has cooled and then dust the rose plants with the solution.
For field horsetail and tansy, proceed as follows:
- Soak 300 grams of fresh or 30 grams of dried herbs in ten liters of water for 24 hours
- then boil for 15 minutes
- mix with water in a ratio of 1:5
- in the case of powdery mildew, spray directly onto the plant
- in the case of downy mildew, give the broth pouring
beneficials
Spread ladybug larvae around the garden as they feed on powdery mildew.
The following types have proven themselves here:
- Halyzia sedecimguttata (Sixteen-spotted Ladybird)
- Psyllobora vigintiduopunctata (Twenty-Two Spot Ladybird)
- Tytthaspis sedecimpunctata (Sixteen-spot Ladybird)
Ladybugs as a biological agent against powdery mildew
Alternative: use biological preparations
The stronger the infestation of your roses with the fungus, the more environmentally friendly preparations that you can buy commercially. Here, for example, the following remedies are recommended, which are specially designed for the infestation of roses.
- Neudorff Fungisan rose and vegetable fungus free
- Neudorff Cueva Mushroom Free
- Compo Duaxo Roses Mushroom Free
Resistant Varieties
There are some varieties that are quite resistant to powdery mildew and with which you can better prevent disease. Basically, this includes all types of roses that have been provided with the ADR mark. The Recognized German Roses are more resistant to fungal diseases, including two variants of powdery mildew. With these types of roses, you don't have to fight the fungi yourself. The following four varieties are particularly recommended.
Rose stem with leaves
- apple blossom
- heather dream
- Palm Garden in Frankfurt
- summer wind
Tip: Even with these roses, it is advisable to regularly remove dried or broken shoots and leaves, as these can be good targets for fungi. Always clean the garden tools afterwards, especially if your specimen is already infested.