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// // // // Powdery mildew on rose

Powdery mildew on rose

Powdery mildew on rose

Pathogen: Sphaerotheca pannosa refers to Erysiphales.



Infection is rapidly spreading, affecting mainly young plants, which, as the disease progresses, begin to rumble, leaves fall and eventually die. The mushroom-causative agent has a high degree of mutation and it is widespread.


Conditions of development of the disease

Powdery mildew of roses is one of the most common diseases of pink bushes. Most often it damages the growing in greenhouses and indoor roses. Erysiphales develops rapidly, infecting new plants. Favorable conditions for development are hot and humid weather during the day, with lowered temperatures at night and the release of condensation on leaves. In cool weather, the fungus is not generally distributed. It also enhances the development of illness with a lack of light.

Symptoms of powdery mildew on roses

The onset of the disease

On the outside of the leaf whitish plague (or with a light pink, gray or brown shade) appears. At first, these are small spots that can be easily wiped out by hand. But already within 1-2 days they grow, cover the leaves completely and pass on their inner side.

Development and consequences of the disease

The mycelium of the fungus rapidly grows, to the touch and outwardly it can be compared to a felt cloth. Further on it formed fruit bodies, which after ripening, begins sporulation and infestation of other plants. The whole process can take 1-2 days under favorable conditions. Mycelium fungus parasitizes on leaves and prevents photosynthesis, the infected plant does not absorb nutrients, begins to dry. As a result, a sick rose bush without treatment dies for 5-7 days. This is especially true for young shoots and plants that do not yet have an odorless part.

Sources and causes of powdery mildew on roses

The spores of powdery mildew fungus are easily spread between plants with the help of air streams, and even wind blasts are not required for this. Also spores are well transmitted with splashes of water and transported by insect pests (thrips, aphids, scales). The causative agent of the disease also hibernates in soil on plant remains.

Preventive measures

Taking into account such prevalence and activity of powdery mildew, preventive measures to control it should be obligatory for all those who grow roses. Prevention includes items:

  1. Careful cleaning of all plant remains and weeds should be regular.
  2. Affected leaves, parts of the bushes must be immediately removed and burned.
  3. It is important to maintain the balance of inputs of nitrogen, phosphorus and potassium fertilizers, avoiding their incorrect proportions and overdose.
  4. Timely pest control.
  5. Greenhouses need to be well ventilated, there should not be condensate on the walls of the greenhouse and plants.