Gray mold (botrytis cinerea)
In years with warm and humid weather, the fungal infection called gray mold spreads particularly aggressively. With the beginning of the planting period, a gray fungal lawn forms on all parts of the plant. As the grapes continue to shrivel and fall off. In the worst case, the very existence of the entire plant is threatened. How to take action against the disease:
- Discard all infected parts of the plant
- do not give nitrogen-stressed fertilizers
- Repeatedly dust the leaves and shoots with primary rock flour
- As a preventive measure, ensure that there is sufficient planting distance
- regularly pruning in February
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The situation is different when the gray mold spreads on ripe grapes. In this case, winemakers speak of noble rot, which is quite desirable. This is primarily the case with red grape varieties.
Downy mildew (Plasmopara viticola)
In addition to powdery mildew, hobby gardeners fear downy mildew as a perennial sword of Damocles in the cultivation of vines. Immediately after budding until September, oily spots appear on the underside of the leaves, which develop into a dirty-white fungus coating. As a result, the grapes are attacked and turn blue-gray. Ultimately, they shrink like a leather bag and fall off.
Approved fungicides for the allotment garden are only preventive. They are mainly based on copper and network sulfur. In order to develop their effect, they should be used immediately after planting. Since these preparations are associated with health concerns when consuming the grapes, environmentally and health-conscious hobby gardeners prefer these ecological methods:
- Plant vines in a row at a dizzying distance
- Mixed culture with marigolds and marigolds keeps fungal spores away
- Inject liverwort extract as a tonic from the start
- Keep deadlines for the pruning
At the first signs of a fungal infection, the grapevine is sprayed with a soap solution every 2-3 days. This is made up of 1 liter of water and 15 milliliters of curd soap and alcohol. In addition, the garden is designed to be inviting for beneficial insects such as ladybugs or parasitic wasps. (€ 14.59 at Amazon *) These insects like to eat fungal spores.
Tips & Tricks
The sensitive area of chemical fungicides is subject to permanent change. The use of these preparations is strictly regulated, especially in small and home gardens. The free pesticide database offers up-to-date guidance on which agents are allowed and which are not. This is operated by the Federal Office for Consumer Protection and Food Safety.