Norway maple - detecting and controlling diseases and pests

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The maple is very robust, but the disease is not immune to some diseases. Verticillium wilt in particular can cause considerable damage to the maple.

Norway maple - detecting and controlling diseases and pests

The maple is a sturdy plant. The plant is very well adapted to our climate and even finds a habitat in the cities. Nevertheless, diseases and pests are not entirely healthy. Care mistakes are often the cause of ailing plants. Thus hobby gardeners can contribute a lot to the health of the maple tree.

The maple tree is particularly susceptible to the following diseases:

  • Powdery mildew
  • Verticillium wilt
  • Teerfleckenkrankheit

How to identify diseases and pests and what to do about them is outlined below.

Powdery mildew - Common but harmless

The powdery mildew infestation is common in specimens planted in cities. Uncinula tulasnei is a species of powdery mildew found in Norway maple. Although powdery mildew occurs quite frequently, no lasting damage to the crop is to be feared.


Visually, an infestation is not to be overlooked. The leaves are covered with a white, flour-like topping.


Remove all affected leaves. These do not belong to the compost and should not be left on the ground. The fungus would survive the winter on the leaves and in the spring again cause damage to the shoot.

" Tip: Incinerate affected parts of plants or dispose of them with household waste.

Powdery mildew can be controlled quite reliably with a proven home remedy. Mix fresh milk and water in a ratio of 1: 9 and vigorously spray the leaves. This treatment should be performed every other day until no more infestation can be detected. It gets more difficult with larger trees, where you can not easily get to the leaves. Here then should be resorted to means that can be administered via the irrigation water.

Verticillium wilt - The aggressive fungus

The Verticillium wilt is widespread and affects hundreds of plant species. Affected are more than 70 trees. In addition to the maple, elms or linden trees are increasingly endangered. The damage caused by Verticillium wilting on strawberries or hops is particularly severe and causes considerable economic damage. At the same time, the soil-borne fungus has been on the rise in the last 20 years.


The fungus leaves leaves and flowers wither. Especially on the maple, cracks develop in the trunk. There are brown to greenish discolorations. The stem necroses occur especially in the lower part of the trunk. At first glance, the hobby gardener might think his Norway maple lacks water. It can happen that the leaves begin to wither and fall in the middle of summer. This is then usually not the result of a casting defect, but can be explained by the fact that the fungus blocks the Wasserleitbahnen of the crop.

" Tip: Verticillium wilt initially affects the older leaves. Younger leaves continue to grow as usual. In the later course, the younger parts of the plant also fall off and the entire plant dies.

Often, the fungal disease occurs in hot summers and during longer periods of drought.


The Verticillium wilting is quite aggressive, especially as against the pathogen so far no suitable means have been found. All parts of the fungus affected by the fungus should be removed immediately. Cut back into the healthy tissue.

" Danger: The maple is not very good at pruning. There is a great deal of plant juice and the tree threatens to bleed if the wounds are not closed with a special remedy.

However, these measures are often too late and the plant is beyond saving. To prevent the fungus from spreading further, remove the plant completely from its root and exchange soil before replanting the area.

Prevent Verticillium wilt

Already during the planting you can do some things for the health of the Spitzahorn. Create optimal site conditions and ensure an adequate supply of water and nutrients. For the Norway maple, a sunny to half-shady location is best. Young plants need sufficient irrigation. The plants should not dry out, but they should not be too wet either. This quickly creates waterlogging that damages the roots. Killing plants are much more susceptible to Verticillium wilting.

Avoid susceptibility through proper plant care

❶ Make sure you have a well drained soil that drains the water well and keeps the plant from waterlogging.
❷ Be careful when planting and do not hurt the sensitive roots.
Unter Mix compost and horn meal (for example, available here) under the substrate. This ensures natural fertilization and keeps the plant healthy.

When pruning, use a sharp and clean gardening tool to seal the cut of the plant with loam or wound sealant.

Tar blight - danger to the leaves

The tar-stain disease is quite common in the maple. The infestation is well recognized by the black leaf spots. The fungus patches appear more distinct from year to year and develop from small, yellow-bordering black spots to conspicuous black vaulting on the leaves. The spots are about one centimeter in size and the yellowish edge is clearly visible. Initially, the leaf spots appear yellowish-green. Infested is the complete leaf.

Tar blight disease is also known as maple ruffle scab. From the mushroom braids, which are also called stroma, forms in the spring of the following year, the fruiting body. The black leaf spots bulge up and get a rather irregular structure. In spring it comes to the ejection of spores, which then infect young leaves.


As a rule, no further action is required. The leaves should be carefully removed and disposed of in autumn. If the infestation occurs massively, a fight with appropriate resources in the spring can make sense.

" Tip: The tar stain is much less common in trees planted in cities than in forest trees, where no regular foliage removal takes place.


Powdery mildewIt is characterized by a whitish, reminiscent of flour on the leaves.
  • Spraying with a water-milk mixture can help.
  • For larger trees, apply suitable water over the irrigation water
  • Remove and dispose of infected leaves.
Verticillium wilt
  • The leaves wither and fall off.
  • First, the older leaves are affected.
  • Sudden leaf fall occurs in the middle of the growing season.
  • The damage is similar to a plant that was not watered enough.
  • So far there is no suitable means.
  • Optimal choice of location and nutrient supply can prevent the disease.
TeerfleckenkrankheitOn the leaves black spots with yellow edges become visible. These grow into ulcerous necroses.The leaves should be completely removed in autumn and disposed of, so that the fungus can not spread further.

Is the Norway maple attacked by pests?

The aphid is virtually permanent guest on the plants. Sustainable damage is not to be feared by the pests. The hobby gardener does not have to intervene here. The work is done quite reliably by the predators of the aphid.

If you live in rural areas, you should protect the trunks of Norway maple from venison. Especially rabbits prefer the trunks of the maple.

Video Board: Crimson King Maple Tree Diseases Review.

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