Although the walnut is one of the more robust tree species, it is not immune to some pests. In this guide, we briefly introduce you to the most important threats and give tips on how to combat them.

Aphids are very fond of walnut trees

aphids

Symptoms of aphid infestation:

  • Honeydew (sticky coating) on the leaves
  • curled and partly crippled leaves
  • yellowing leaves
  • dried and falling leaves
  • Colonies (especially on new shoots)

Note: You must analyze the leaves up close to spot aphids. The animals are only a few millimeters in size and brown, black or greenish in color.

Measures to combat:

Variant 1 (with manageable infestation):

  • Cut off affected branches down to the healthy area.
  • Then spray the tree with strong pressure. This is how you wash away the remaining lice.

Variant 2 (for severe infestation):

  • Make a highly concentrated soapy solution and add about 500 milliliters of canola oil for every ten liters. The oil clogs the lice's respiratory organs.
  • Spray the walnut tree to dripping wet.
  • Repeat the process after about three days.

caterpillars

The following caterpillars like to tamper with walnut trees and often leave behind massive damage:

  • bluesie caterpillars
  • willow borers
  • butterfly caterpillars

Optical characteristics of the caterpillars:

  • yellowish white color
  • up to 6 cm tall
  • Point warts on the body

The animals eat into the inside of branches and trunks and gradually form a hollow tunnel system there.

Measures to combat:

  • Be sure to react early, i.e. before the caterpillars have worked their way inside the tree. Once the insects get there, you can't reach them.
  • If possible (few caterpillars and low tree), collect the caterpillars by hand.
  • Alternatively, shake the caterpillars down. For this purpose, you should put a slide on the floor. Then shake the tree (for a small specimen) or work your way from branch to branch with a broom. Dispose of the caterpillars that fell on the foil in the household waste.
  • In the case of a mild infestation in the early stages, you have the option of cutting off the affected branches. For tall trees, we recommend using telescopic pruning shears.
  • Neem oil (plant products) are also suitable for controlling caterpillars. Spray your walnut tree or the affected parts of the plant with it. The oil gets stuck in the caterpillars' airways, causing them to suffocate.

Note: The most important pest of the walnut tree is the walnut fruit fly, about which we have made a separate post.

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Vegetable garden