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Gnomonia leptostyla (Fr.) Ces. et de Not.


Crops attacked: walnut .

[R]Common Names :


Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images


The fungus attacks the leaves and young fruits.
In summer, on leaves, greyish lesions with brown margins occur scattered or along the main veins.
They can cause more or less severe premature defoliation and the drying out of fruits.
When the season is over, dark brown spots with grey dotted margins occur on the fruits.

The fungus overwinters on the dead leaves where it produces perithecia in spring. The released ascospores cause the primary infection while the conidia forming on the lesions disseminate the disease throughout the season.

Temperature around 21 C. and high RH (96-100%) facilitate the spread of the disease.
Conidia can survive without water for two weeks.

Copper treatments against bacterial blight are usually efficient also against G. leptostyla .
Remove the dead leaves in the nurseries.

[R]Possible misleading

[R] Images

  1. Gnomonia leptostyla , Walnut-tree anthracnose (GUILLAUMIN J-J., INRA)
    Walnut-tree anthracnose Anthracnose symptoms on walnut.
  2. Marssonina juglandis , Walnut-tree anthracnose (I.VEGH, INRA)
    Walnut-tree anthracnose Spots of anthracnose on young fruits.
  3. Marssonina juglandis , Walnut-tree anthracnose (VEGH I., INRA)
    Walnut-tree anthracnose A walnut infected by Marsonina juglandis .

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HYP3 on line : Species (scientific name), Diseases (common names), Glossary, Crops.

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