Cherry laurel is very popular as a hedge plant in this country. The evergreen shrub with the large glossy leaves grows upright and extremely fast. However, cherry laurel is often attacked by powdery mildew.

In a nutshell

  • powdery mildew mainly affects young leaves
  • Signs of white mealy coating on the underside of the leaves
  • remove affected plant parts
  • Use of wetted sulfur preparations
  • Avoid care mistakes

Powdery mildew most common fungal disease

The universally popular shrub, the cherry laurel (Prunus laurocerasus), also known as the laurel cherry, is very fast-growing, tolerates pruning well, is hardy and also grows under unfavorable conditions. It is therefore a welcome guest in gardens. However, the cherry laurel is not spared from fungal diseases such as the dreaded powdery mildew. It is the most common disease in laurel cherries. When the first signs appear, quick action is necessary to prevent more serious damage to the plants.

recognize illness

Before you start fighting this fungal disease, you should take a closer look at the causes of its development. The trigger for the disease is the infestation of the cherry laurel with the fungus Podosphaera tridactyla. A distinction can be made between real and false powdery mildew on the cherry laurel. Both types can attack the shrub.

powdery mildew

It is also known as the fair-weather mushroom. The spores (conidia) get onto the leaves with the wind or spray water when watering. There they begin to germinate and finally penetrate the top cell layer of the leaf. A fungal network, the mycelium, then forms. In summer, the fruiting bodies (ascospores) then develop on this. They hibernate on the plant in the tips of the shoots until next spring. The mushrooms appear from April to September. To grow, this powdery mildew needs:

  • Temperatures of at least 10 to 12 °C for germination and
  • dry, warm weather, as well
  • nocturnal dew formation

Wrong mildew

This type of powdery mildew usually occurs in autumn and can also affect cherry laurel. The mushrooms love damp and cool weather and are therefore also known as bad weather mushrooms. The spores float on the moist leaves, penetrating stomata on the underside of the leaves. They overwinter in shoot tips and in fallen leaves.

Mistakes in care as causes

In addition to the weather, a wide variety of mistakes in care can also promote the development of the fungus. Mainly, wrong watering and fertilizing can create good conditions for the spread of powdery mildew. The biggest mistakes are:

  • nitrogen fertilization of the soil
  • silicate deficiency
  • wet the leaves when watering
  • wrong location
  • no air circulation to dry the leaves
  • too small plant spacing
  • resulting in high humidity

Notice: The cherry laurel can easily be confused with the laurel tree (Laurus nobilis), whose leaves are used as a spice. The leaves of the cherry laurel, on the other hand, contain cyanogenic glycosides that release hydrocyanic acid when chewed.

Typical symptoms

As a rule, the youngest leaves of cherry laurel are attacked by powdery mildew, while older ones are spared. The following signs are characteristic of the “fair-weather mushroom”:

  • young leaves and shoots show light discoloration
  • from April, floury white coating on the underside of the leaves
  • later turns brownish to greyish
  • is wipeable
  • from mid-May visible changes in the leaves
  • Bulges and deformations on the upper side of the leaf
  • affected areas initially yellow, later brown
  • severe curling of the leaves possible
  • tearing of leaf tissue
  • crippling of the leaves
  • sometimes one-sided curvature of the sheet
  • Leaves no longer grow
  • at an advanced stage infestation of young shoot tips, buds and fruits and
  • Leaves turn brown, dry from the edge
  • in addition, blotchy brown corking can occur on the underside of the leaves
  • in the final stage, the upper parts of the shoot die off completely

Even with the "bad weather fungus" affected leaves die off over time. Violet, yellow or brownish discolorations appear on the leaf surface. Just as with the "fair weather fungus", a whitish-grey fungus coating is also visible on the underside of the leaf. Therefore, it can quickly lead to confusion between the two fungal diseases. It is then advisable to examine the leaves carefully with a magnifying glass.

Tip: Mainly strong-growing and broad-leaved varieties such as "Etna", "Rotundifolia" or "Schipkaensis Macrophylla" are affected.

fight properly

If the first signs indicate that your cherry laurel is infested with powdery mildew, you must act quickly to prevent the fungus from spreading to other plants. The following measures can be helpful:

  • remove affected leaves
  • Cut back diseased shoots vigorously
  • Cut back deep into the healthy wood
  • if the infestation is very severe, remove the plant
  • do not dispose of infected parts in the compost
  • Disposal in household waste
  • Use of wetted sulfur preparations

Notice: Chemical preparations based on copper or wetted sulfur are environmentally friendly. They will even be used in organic farming.

use of fungicides

If nothing else helps and the disease is already far advanced, only the use of fungicides will help. are recommended

  • Fungisan Roses - and Vegetables Fungal Free or
  • duaxo

The preparations are diluted with water and the plants are sprayed with it. The injections should be repeated after 10 to 14 days. They can also be used in the following year from the end of March to the beginning of April to prevent reinfestation.

Fight with home remedies

Many hobby gardeners swear by the use of proven home remedies to combat this dreaded fungal disease. Whether the treatment is always successful depends largely on the stage of the powdery mildew on the cherry laurel. It's best to try it yourself. are promising

vinegar and water mixture

  • 1 tablespoon apple cider vinegar
  • 1 liter of water
  • mix everything well
  • put in spray bottle
  • spray affected areas
  • Application for several days in a row
  • Treatment in the morning and in the evening
  • not in direct sunlight
  • Leaves can burn

fresh milk

  • do not use UHT milk
  • Mix 1 part milk with 9 parts water
  • Spray leaves/shoots well every other day
  • Treatment until fungus is dead
  • Microorganisms in the milk fight fungi
  • at the same time, the sodium phosphate it contains strengthens the plant's defences

Preventive treatment can also be carried out in the months of April to the end of July. Initially, susceptible plants are sprayed once a week, and then every two weeks. The bacteria contained in the milk multiply on the leaves and form a dense coating.

preventive measures

Prevention is always better than cure. In addition, the causes of the infestation of your cherry laurel with powdery mildew should also be known. However, subsequent measures are not always a guarantee that the fungal disease will not break out, as it also depends on the weather. But there is a possibility to reduce the attack points. It should therefore be noted:

  • right choice of location
  • sunny to semi-shady
  • Planting of resistant varieties
  • enough planting distance
  • varies depending on the variety
  • regular pruning
  • no summer cut
  • since newly sprouting leaves are very susceptible
  • Cut back in autumn or early spring, at the end of February
  • Avoid over-fertilization with nitrogen
  • as a result, plant tissue becomes soft and fungus can easily penetrate
  • Use potash-rich fertilization
  • Water plants from below
  • Watering in the morning or afternoon gas
  • Leaves must be dry by night
  • Keep the soil weed-free and mulch
  • Use of plant manure to strengthen the body's defences
  • nettle or horsetail broth is particularly suitable
nettle manure

frequently asked Questions

What should be considered when producing plant manure?

To prepare nettle or field horsetail broth, 1 kg of fresh or 150 g of dried leaves are required. These are soaked in 10 liters of water for 24 hours and then boiled and strained for 30 minutes. For pouring, the broth is diluted with five times the amount of water.

Are there any other home remedies to combat fungal disease?

Garlic broth can also be used. To do this, 4 cloves of garlic are crushed and poured over a liter of hot water. Then let everything stand for a few hours, strain and spray the affected parts. Neem oil can also be used for treatment.

Can powdery mildew be dangerous for humans?

He's not poisonous. However, allergic reactions such as breathing problems, itching or reddening of the skin, as well as stomach problems can occur. Therefore, gloves and a face mask should be worn when treating affected plants.

Category:

Garden plants