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Grey mould
Grey mould is caused by the fungus Botrytis cinerea, which contaminates the grapevine’s tissues. The conditions favourable to the development of this disease are: average temperatures, high relative humidity and the existence of wounds or injuries on the plants.
The grey mould fungus hibernates in the stalks in the form of sclerotia, or in the stalks and buds in the form of mycelium. In spring (especially the fresh and humid springs), the fungus settles in the bracts near the inflorescences and develops throughout the remains of the flowers that become sticky. Afterwards, the bunch ends up necrosing.
Grey mould attacks on the leaves or during flowering do not interfere in the setting. However, from the veraison stage onwards the conidia can germinate on the berries, thus originating mycelium, which spreads and enters the berry epidermis. The mycelium evolves and produces conidiophores, which release conidia. When the conidia land on other berries, they will spread the disease. The berries affected by grey mould produce unbalanced wines.
Leaves:
- Brownish spots in the periphery of the blade, delimited by the ribs
Inflorescences:
- Necrotic spots that can lead to partial or total death
Bunches:
- Appearance of more or less round lilac spots in red bunches
- Appearance of brownish spots in white grape varieties
- Dry, wrinkled berries
- Wet rot, usually covered with a grey mould
Cultural control:
It is important to choose a vineyard that is resistant and has a balanced vigour. The vine training system should allow good aeration and some green interventions should be performed, such as defoliation and topping. Regarding the soil, it is important not to over-water it.
Chemical control:
- Dicarboximides (iprodione, procymidone, vinclozolin)
- Anilinopyrimidines (cyprodinil, cyprodinil + fludioxonil, pyrimethanil, mepanipyrim)
- Hydroxyanilide (fenhexamid)
- Sulphamide (tolyfluanid)
- Avoid the use of mancozeb, propineb and zineb
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