Help the development of the site, sharing the article with friends!

Roses can be found in almost every garden in this country. Nevertheless, the ornamental plant is also very susceptible to diseases, which can also lead to leaf discoloration, among other things. You should do that, your roses will get red leaves.

In a nutshell

  • often due to fungal or viral infections
  • precise damage pattern enables precise allocation
  • rapid treatment ensures survival
  • intensive and species-appropriate care reduces the risk of infection

causes

There are many reasons for the discolouration of the usually dark green leaves. In most cases, however, the origin lies in an infestation by fungal spores or viruses.

Among the most common causes of red leaves on roses are diseases such as mosaic disease, bark/burn disease, rose rust and red pustule fungus.

Mosaic Disease

Mosaic disease, unlike many other diseases, is transmitted by viruses. In most cases, the disease can already be recognized in the spring by reddish leaves. The pattern is reminiscent of that of a mosaic. In addition, the leaf veins in advanced stages have a yellowish color and thus stand out clearly. The leaf structure also becomes more wavy if the disease persists.

The consequences of not treating mosaic disease are:

  • slowdown in plant development
  • formation of smaller leaves and flowers
  • defoliate
  • decreasing efficiency of the immune system
  • increased risk of infection for other diseases

Bark/burn spot disease

Burn spot disease (Coniothyrium wernsdorffiae), also known as bark spot disease, occurs more often on trunks and shoots, but can also spread to leaves and flowers. The red-brownish marks that appear give the impression of a burn injury and already extend over several centimeters at the beginning. In the course of time, the "burn" expands and causes all branches above to die off. The cause of infection with the fungus is contamination of wounds on the plant. Old shoots are particularly susceptible to infection, as are plants that are fertilized with high levels of nitrogen.

rose rust

This disease can be recognized in its early stages by orange or red spots on the tops of the leaves of your roses. As the fungal attack progresses, the individual spots flow together and form a uniform rust-red discoloration. The spores of the fungi, which are of the same color, often stand out clearly from the leaf itself. On the underside of the leaf, an infestation usually only shows up in stripes and is not continuous, even in advanced stages. The consequences of rose rust (Phragmidium mucronatum) range from:

  • shedding of all leaves
  • reduced plant growth
  • no or very little development of new shoots and buds
  • death of the plant

red pustular disease

The red pustule fungus (Nectria cinnabrina) is generally a helpful aid in the decomposition of deadwood. In addition to completely dead parts of the plant, the spores also increasingly infest living areas and cause irreparable damage. However, the origin of an infection can often be found on dead branches left on roses.

Causes of dead branches can be:

  • frost
  • insufficient nutrient supply
  • lack of moisture
  • natural selection of the plant
  • existing disease or pest infestation

From this source of infection, the toxic substances of the red pustules spread through the plant veins within a very short time and ultimately lead to the death of the entire plant.

treat diseases

Regardless of the disease that has occurred, prompt treatment is an essential guarantee of success. With every day that passes without proper treatment, the chance that the roses will recover decreases. This is mainly due to the decreasing effect of the immune system and the increased susceptibility to other diseases.

For a promising treatment, the following tips should be applied:

  • when planting in containers: remove the plant as far as possible from other plants
  • Generously cut back affected shoots, including leaves and flowers
  • Apply fungicide from a specialist dealer according to the instructions on the package

In the case of an existing fungal or viral infestation, patience is required after the treatment has been completed. The first signs of a survived infection, such as the formation of new shoots, usually take several weeks to appear. It may also be necessary to treat the rose again if the symptoms worsen again.

Notice: In particular, make sure not to dispose of the branches cut off the affected plant in the compost, otherwise there is a risk of reinfection through fertilization.

Prevent

In most cases, a viral or fungal disease results from an open cut that allows the pathogens to enter the plant. In order to reduce the risk of infection, especially in the case of the necessary annual pruning, a few tips have proven themselves in practice. How to prevent unwanted red leaves on your roses:

  • only on dry and frost-free days
  • Be sure to remove deadwood
  • Use wound closure agents

Notice: In addition to the commercially available products, liquid candle wax, charcoal powder, clay or animal manure are also suitable for optimal wound closure.

In addition, plant-specific care helps to reduce susceptibility to diseases. In addition to choosing a suitable location, irrigation and fertilization also play a crucial role. Since most mushrooms prefer moist conditions, it's best to focus watering solely on the root area. Watering the leaves over a large area should be avoided if possible.

Tip: In order to facilitate drying during heavy rainfall, the annual pruning of the plant should be used for thinning out measures. As a result, this leads to increased ventilation of the individual shoots and thus to a faster drying process.

frequently asked Questions

Are fertilizers also suitable for preventive treatment?

Balanced fertilization is of great importance for maintaining a healthy and functioning immune system. The use of nettle manure has proven itself in practice as a remedy against any pests and pathogens. In order to avoid the negative consequences of over-fertilization, however, the fertilizer should be applied at intervals of at least four weeks and never undiluted.

What should be done with the plant parts that have fallen off?

The leaves and flowers that have fallen off infected plants should not be disposed of in the compost, just like the cut shoots. In order to prevent re-infection, the plant parts should ideally be disposed of in the residual waste.

Are there any roses that are resistant to the aforementioned diseases?

In principle, there is currently no known variety that is immune to all diseases. Nevertheless, particularly resistant varieties can be identified with the help of the ADR seal. Varieties that are awarded this seal showed hardly any susceptibility to pathogens within a three-year test period. The certified species include the roses of the Sirius, Elbflorenz, Golden Gate and Heidetraum breeds.

What other reasons can there be for red discolored leaves?

A disease of the plant does not always have to be behind reddish leaves. The newly developed shoots of the roses naturally have an intense reddish color in the first few months, which changes to the well-known dark green over time. A similar discoloration can also be observed in autumn, which is due to the increased production of anthocyanins (red plant pigment).

What are the advantages of reddish leaf coloring?

The red coloring of the leaves provides a natural protection against sun burns compared to the usual dark green color.

Help the development of the site, sharing the article with friends!

Category:

Garden plants