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Walnut diseases, how to fight them


Thewalnut diseasesthey can be caused by various insects, fungi and bacteria. Thewalnut diseasesthey can compromise the productivity of this plant both from a qualitative point of view, and from a quantitative point of view with little or no yields.


On this page we will see the most commondiseases of the walnut treeso as to complete our collection of articles concerning thewalnut cultivation:

  • How to grow the walnut tree
  • How to collect nuts
  • How to grow walnuts
  • Walnuts, all varieties
  • How to cure walnut, other diseases such as:
    -fungal diseases
    -bacteriosis
    - thinning pruning for prevention
    -black spots
    -treatments for the prevention of bacteriosis and fungal diseases

Diseases of the walnut

The walnut is exposed to attacks by insects and fungal and bacterial diseases. Diseases can affect trunk, branches, leaves and fruits.

Diseases of the walnut: aphids
There are essentially two aphids that can cause walnut tree diseases: Panaphis juglandis and Chromaphis juglandicola. If observing the upper vein of the leaves you notice a colony of aphids, it will undoubtedly be Panaphis juglandis, on the contrary, the aphid of the Chromaphis juglandicola species infests the lower page. Walnut aphids can cause necrosis of the tissues affected by the stings, damage the plant and cause its defoliation. It is necessary to intervene especially when the attacked walnut is a young plant. To eliminate walnut aphids, a treatment with azadirachtin-1 (bio) must be performed at a dose of 300 ml per 100 liters of water to be sprayed on the areas affected by the aphid infestation.

Diseases of the walnut: red and yellow wood
Rodilegno are butterflies that feed on a large number of tree species, including the walnut. The red woodpecker has larvae that, when fully developed, reach a length of 9-10 cm (they are red). Woodworms dig tunnels at the collar or in the lower trunk. Initially the larvae live together and tunnel just below the bark, only later do the larvae separate and dig individual and deeper tunnels. Similarly, the yellow wood will damage the walnut tree by digging tunnels.

The fight against these larvae is rather difficult. There are pheromone-based traps on the market: those for the red rodent wood must be hung in the middle of the walnuts, about one meter high. Those for the yellow wood should be placed (at the end of May) beyond the height of the foliage, hanging from a pole with a side arm. To eliminate the woodworms when they are still larvae, it will be necessary to intercept the tunnels and insert a wire inside them until they are mechanically killed.

Diseases of the walnut: the nut fly
The walnut fly flies between June and late September (when temperatures aregood also October). in this period the females lay their eggs under the surface of the husk. From the eggs hatch larvae that feed on the same husk until it dries up and causes the formation of rotten nuts. The walnuts fall to the ground and host the larva (which will have turned into a pupa) until the following year, when the adult is formed. It is for this reason that it is good to eliminate all rotten walnuts found at the foot of the walnut.

To fight the walnut fly it is possible to use trap bottles that must be filled with half a liter of concentrated ammonia at 5%, adding a raw sardine as a protein bait. These baits are hung on the branches, on the outside and on the south side of the canopy (sunniest), in a number of 2-3 per plants. The traps must be kept up and running from June to September.

To maintain their effectiveness, it is good to replace the sardine once a month and use a trap that does not allow rain to enter. Among the various proposals on the market we point out the traps TAP-TRAP, shown in the photo above.



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