The Content Of The Article:
- Damage pictures, diagnosis
- Rose rust
- Wrong mildew
- Tip: A good pruning ensures adequate ventilation of the rose.
- Soil, fertilize
- Mushroom-resistant rose varieties
When the beloved rose bush suddenly gets brown leaves, panic breaks out. Is it a dreaded fungal disease? If yes, which? And most of all, what can I do?
Another scenario: The desire for roses in the garden is great! But how often do you hear that roses are very susceptible to pests and diseases. Should one dare anyway? - Yes, it's definitely worth it! Because a lot can be done right from the start to keep the risk for illnesses as low as possible.
Damage pictures, diagnosisUnfortunately, there are several fungal diseases that are noticeable by brown spots on the rose petals. In most cases, two, quite common for roses, fungal diseases behind it: the Sternrußtau and the rose rust. Somewhat less common is the downy mildew, initially with brown spots on the leaves.
- Infestation visible from April, May
- Affected older leaves in the lower area
- different sized spots on the top of the leaves
- Stains round, irregularly shaped
- Spots black-brown
- Spots radiating outward at the edge
- Environment of the spots yellow, orange colored discolored
- in summer the leaves turn yellow
- Leaves fall off
- Limited assimilation
- Rose is very weak
- hardly any new flowers
- Shoots do not ripen
- lower frost hardness
- Infestation visible in spring
- Leaf tops show yellowish, rust-red spots
- Stains with dark edges
- Stains turn brownish to black
- Stains are merging
- Leaf underside oblong spore bearing
- Spores first yellow then dark brown
- Leaves fall off
- Infestation visible on the leaf top
- dark spots that go to purple
- Stains mostly limited by the leaf veins
- Spots later reddish brown
- Spots on the underside of the leaves brown
- the greyish mushroom coating forms from this
- Stems also show reddish spots
- Leaves fall off
- Buds dry up
- poor growth
blackspotRoses are most commonly attacked by the black speck (Diplocarpon rosae). The Sternrußtau, also called black spot disease, belongs to the ascomycetes.
The best living conditions for the Sternrußtau are a humid weather, temperatures between 10° C and 15° C and a leaf wetness that lasts more than seven hours.
Until he finds the favorable conditions, he stores the winter over in the soil, in the fallen, sick leaves, in the shoots and buds. The fruiting bodies are not visible to the naked eye. They later form the spurs, which spread only when they encounter favorable conditions. You may be able to wait several years for this. Even temperatures that are colder than -15° C, they can not harm.
Rose rustThe rose rust (Phragmidium mucronatum) does not appear as regularly as the Sternrußtau. It is a so-called parasitic fungus and belongs to the order of rust fungi. For its life cycle, in the course of the infection, it goes through five consecutive spore forms. He overwinters in infested leaves or twigs.
The best conditions for this fungus are a leaf wet period from two hours and temperatures around 20° C. In spring, the spores are spread by the wind.
Wrong mildewPeronospora sparsa from an order of fungal fungi (Peronosporales) of egg flocks, grows in a leaf tissue of its host plants. The spores are transmitted through the air and through splash water. As a thick-walled, resilient spore, it hibernates in the plant. The best conditions are the downy mildew in damp, cool weather. This means that a relatively high humidity at 15° C to 20° C is optimal.
fightOnce you have discovered one of these three fungal diseases on your roses, you should act quickly. It could already be too late for a purely biological defense. These fungal diseases can be completely destroyed, if only with fungicides (poisons against fungi). As spores, they are not only invisible but also so resilient that they defy most biological resources. The following measures and prescriptions can be applied to all three fungal diseases.
- remove affected leaves and plant parts
- Dispose of in residual waste
- or burn
- Disinfect the scissors afterwards (with boiling water, alcohol)
- if necessary, treat with a fungicide (see chemical agents)
- Strengthen rose (see accompanying measures)
Accompanying measuresIn case of fungal attack, the rose itself must be strengthened in any case. Similarly, as with sick people, they now need all the support to strengthen their immune system.
- Check soil: the pH should be between 5.5 and 7
- If the soil is too acidic, incorporate algae meal or rock flour
- regularly with mature nettle (very diluted) watering
- Loosen soil and remove weeds
- do not fertilize nitrogen
- Cum Rose with horsetail tea
- never pour from above, always close to the ground
- Before and after hibernation thoroughly clean the soil around the rose
In an existing fungal infection help only chemical control agents. The individual means can be obtained in advance from the Federal Office for Consumer Protection and Food Safety. They maintain a database of all plant protection products that are also approved for private gardens.
There are different active ingredients, some of them are not bee dangerous others. Most of these remedies also destroy other beneficial insects such as parasitic wasps. It is best if they are not even used. In any case, one should be informed before an application, thoroughly informed or advised in a garden nursery.
preventionThe prevention of fungal diseases is a far more rewarding, albeit labor-intensive, measure. But just who enjoys an ecological natural garden with many roses will be successful and, above all, happier with this type of control.
LocationA very important requirement for healthy roses is their location. He should be chosen so that a good air circulation is given. This allows the leaves to dry quickly after each downpour. Constantly moist foliage is an invitation to mushroom spores.
A sunny location is ideal, but not in a sheltered corner. For a better ventilation, care should be taken to ensure a sufficient planting distance to other roses or plants. It is best not to plant a new rose again in a location where a rose was previously. If this can not be avoided, the earth must be generously replaced.
Tip: A good pruning ensures adequate ventilation of the rose.
Soil, fertilizeThe soil should be loamy, humic and permeable, never compacted and permanently wet. The roses love an acid-poor substrate. Therefore, be careful with nitrogen-stressed fertilizer. Fast-growing shoots attract aphids.
Anyway, too many nutrients weaken the rose more. It is best to fertilize only with organic fertilizer or compost.
Tip: A potassium deficiency can be compensated by a natural fertilizer with coffee grounds or rhubarb. (Signs of potassium deficiency: flowers remain small, young leaves are slightly reddish)
tonicNature has a lot of material to give roses to prevent fungal diseases. Some of them can prevent further spread even at the beginning of infestation. Suggestions for a biological prevention against fungal attack:
bicarbonate of soda
Once the shoot starts, spray the roses with a mixture of water and soda every 14 days for a while.
- 10 liters of water
- 50 grams of soda
When the first buds become visible, in May, sprinkle garlic on the leaves, and especially on the ground. Best every second or third day. Repeat this at least three times.
- 10 liters of water
- 75 grams of garlic
- Chop the toes roughly and boil first with one liter of water
- leave for at least 24 hours
- then sift and dilute
Also against fungal diseases should help a water-milk mixture. At least it can, so some professional experiments, stop the infestation. For this, make a mixture in the ratio of 1:10 (milk: water) and proceed as with "soda".
Jauchen, teas, cold water extracts and brothsSpraying and pouring with certain plant preparations is an effective preventive measure against fungal diseases. In high dilution, they can also be used as fertilizer in irrigation water. Beware of comfrey and stinging nettle, they are highly nitrogenous.
A treatment for the prevention of fungal diseases should take place every two weeks from April. It is best to have cloudy days with light wind so that the leaves can peel off quickly.
Crushed fresh or dried plant parts in a container with cold water in the sun. Cover airtight and stir daily. It should be achieved a fermentation. Fresh manure (bubbles rising) in a ratio of 1:50 with water on the plant splash. Suitable: nettle, comfrey.
Pour shredded plants with boiling water and leave for at least 10 minutes. Use with a 1:10 or 1:20 dilution. For example: garlic, onions.
Cold water extract
For a cold water extract, fresh or dried parts of the plant are soaked in water for a maximum of three days. It must not come to fermentation. The seeped liquid can be used undiluted or in a ratio of 1: 1 with water. Suitable for fungal diseases: field horsetail, stinging nettle, comfrey
For a broth, use 1kg of fish or dried plant parts per 10 liters of water. Before that, the material is soaked in a little water for one day and then cooked for half an hour. Then cool, strain and dilute with water. This preparation with field horsetail is suitable against fungal diseases.
Tip: Some tobacco soaked in water for 1-2 days, but without boil, should also stop the fungal attacks.
Mushroom-resistant rose varietiesLast but not least, at the very beginning, you can minimize the risk of fungal infections by making sure you buy the most fungus-resistant varieties of roses when shopping. A help in purchasing can be the expertise of a corresponding nursery. Also, the ADR seal is quite reliable and currently particularly robust rose varieties.
ADR stands for "Allgemeine Deutsche Rosenneuheitenprüfung". This is an expert panel from the Association of German tree nurseries (BdB) and rose breeders. They also test new varieties of roses to determine if they can survive the three-year testing period without pesticides and, of course, without disease.
Some (few) examples of particularly fungus-resistant, robust rose varieties:
- 'Heidesommer' white, Kordes 1985
- 'Snowflake' white, Noack 1991, ADR Rose
- Rosa rugosa 'Alba', white, Asian wild rose
- 'Graham Thomas', yellow, David Austin 1983
- 'Felicitas', pink, Kordes 1998, ADR Rose
- 'Windrose', light pink, Noack 1993, ADR-Rose
- 'The Alexandra Rose', pink-yellow, David Austin 1992
If you do not want to invest so much time in rose care, but do not want to give up these magnificent, relatively demanding plants, you should definitely choose the right variety when shopping. If an infestation with fungal diseases detects early in the year, it is usually possible to prevent even the worst, even without chemical pesticides. Experience has shown that a light and airy location for the rose is one of the most important prerequisites for protecting it from fungal diseases.