The walnut tree is one of the most robust tree species. Nevertheless, he is not entirely spared from illnesses. One of the most common problems with walnuts is fungal infestation. Our guide explains how this can be recognized and how you can counteract it.

Stains on the leaves often indicate a fungal disease

Countless types of mushrooms possible

Unfortunately, there are numerous types of fungi that settle in gardens year after year and sometimes nest on walnut trees. Some trigger strong, life-threatening damage, others can be fought relatively well.

Important: You should ALWAYS act immediately if you notice a fungal infection on your walnut tree. In most cases, an exact identification of the respective fungus is not possible (at most you could consult an expert).

Note: The most important fungus associated with walnuts is Diplocarpon mali, which causes Marssonina disease.

Symptoms of a fungal infestation

Walnut trees usually show the following symptoms of fungal infestation:

  • brown and/or greyish-brown leaf discolouration
  • curled and/or stunted leaves
  • Leaves dry out and fall off more often
  • new shoots fail/grow very thin
  • thin green twigs hang down helplessly
  • Infructescences fail/do not develop properly
  • Tree thins out more and more
  • Smear coating on the leaves and/or on the green branches

Combat fungal infection in walnut

Fungicides specially formulated for treating fungus in fruit trees usually work the fastest and best. We advise you to only use organic products. These even ensure that you can harvest and enjoy any fruit that may be present despite the treatment in autumn. In addition, organic fungicides are environmentally friendly.

Note: If you decide to use chemical products, you have to reckon with the fact that the walnuts will be contaminated afterwards. Then you should NOT eat the nuts. Incidentally, chemical fungicides are also toxic to insects. For this reason, it is not advisable to use such products.

Extra: Tree fungus infestation

The fungal infections defined above refer to fungal species that trigger an optically small fungal spore infestation. In addition, however, there is also tree fungal infestation - this is observed much more frequently: easily recognizable fungus sponges form, very often on the tree trunk.

There are two things to keep in mind:

  • Tree mushrooms aren't always edible (although they might look inviting).
  • Tree fungi are not necessarily harmful to walnut trees.

Despite the second point, you should act:

  1. Clear tree fungus to prevent spread.
  2. Score the bark/wood with a sharp knife.
  3. Green tissue present? Fighting can still work!
  4. Inner fabric dried out/shimmering yellowish-green? Fungus has penetrated the inside of the walnut and conventional measures no longer make sense.
  5. In the latter case consult experts from the Plant Protection Office.

Category:

Vegetable garden