Main symptoms


Symptoms caused by Xylophilus ampelinus appear mostly in spring and mid-summer. They fluctuate according to bacterial strains, grape varieties, cultivation techniques, and environmental conditions. It should be noted that the bacteria can be present in a latent state on the vine, without the latter expressing any symptoms.

  • Buds

This bacteria prevents bud break or slows it down. Subsequently, poorly developed young shoots can be observed, wilting and gradually drying out. 

  • Leaves

Symptoms on the leaves can be different depending on the location of the bacteria on and in the vine.

- If X. ampelinus has an epiphytic development (on the surface of the lower leaves of the vine shoots), this bacterium, penetrating through the stomata and colonizing the parenchyma, causes small angular oily spots, 1 to 3 mm in diameter, of a brown tint dark at term, and surrounded by a more or less marked chlorotic halo (figures 1 and 2). Note that when the attacks take place on young leaves, these in the presence of spots can be more or less deformed (figure 3).
- When it colonizes the vessels, as in the case of many vascular diseases, yellowing and more or less sectorial dryings appear on the leaves, frequently starting at the periphery of the blade (figure 4). Ultimately, the necrotic, tan colored, non-functional leaves may drop.

  • Peduncles and twigs

Longitudinal oily lesions, brown to black, more or less canker at term, bursts, cracks can be observed on the peduncles and the stalk of the bunches, on the twigs (figures 5 to 8) and the branches.

  • Inflorescences

A sagging of the flower buds (figure 9), dryness sometimes appears on the inflorescences.

Last change : 04/20/21
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