Fight powdery mildew on wine

While powdery mildew on plants in your own garden is just a nuisance, this fungal disease is a real horror for agriculture. Grapevines in particular suffer severely from the infection and it is therefore necessary to prevent and combat any possible infestation. Wine can be attacked by powdery mildew and downy mildew, which, along with phylloxera, is one of the greatest problems in viticulture. Even in the home garden is not to be trifled with.

Where does the powdery mildew come from?

Powdery mildew and downy mildew that attack grapevines have only appeared since the middle of the 19th century. Century in Europe. The mushrooms originally come from North America and were introduced there between 1845 and 1878, around the same time as the phylloxera. Since that time, the fungi and lice have been the biggest pests and diseases for viticulture in Europe, as the native species are hardly resistant to powdery mildew and therefore prey on them in large numbers fall. This is what makes these mushrooms so dangerous, even with solitary grapevine bushes that are kept purely for ornamentation or for low annual crop yields.

Note: Not all types of powdery mildew affect every plant. Powdery mildew fungi in particular specialize in a certain type of plant and this also applies to wine, which suffers heavily from the infestation.

Powdery mildew in detail

Powdery mildew is a disease of various types of grapevine caused by the pathogen "Erysiphe necator", which is one of the so-called fair-weather fungi. The disease is also known through the hose fungus under the names Oidium or Äscherich, which mainly indicates the greyish color of the plant as soon as the infestation has progressed strongly is. The hose fungus attacks the wine by collecting on the surface of the plant parts and penetrating them via suction organs, more precisely into their cells. The fungus thus intervenes in the nutrient balance of the grapevine and has a negative effect on it with the following symptoms:

• white-gray spots form under and on the leaves
• also net-like structures that are reminiscent of cobwebs
• the more the vines are affected, the more parts of the plant are affected: shoots, flowers, buds, grapes
• the layer looks floury, slightly moldy
• Leaves roll up
• Flowers can no longer open
• Grapes become hard, turn gray or black and break the seeds and are no longer edible
• Growth is restricted
• Grapevine gradually dies
• later stages: spots turn gray-brownish in color

The breakage of seeds in particular is devastating for viticulture, as the grapes can no longer be used for the production of wine. Slightly infected fruits, on the other hand, cause an unpleasant aroma, so-called wine defects, which can greatly reduce the value of a product. Furthermore, the vines can be infested with other pathogens through the broken seeds. However, the infection by the fungi can occur at a temperature of over 7 ° C in spring, optimal temperatures are between 20 ° C and 27 ° C, but temperatures up to 35 ° C are tolerated. Hence, they are also called fair weather mushrooms because they prefer warmth and dryness. The following grape varieties are particularly susceptible to these mushrooms:

• Blue Portuguese
• Blue burger
• Müller Thurgau
• Scheurebe
• Silvaner

Wrong mildew

Downy mildew is caused by the pathogen "Plasmopara viticola", which is a so-called false or egg fungus. Compared to powdery mildew, they are known as bad weather mushrooms and prefer a moist environment. The infestation is particularly effective as soon as the nights are damp. Rain is the best transmitter of all powdery mildew fungi, as it can infect the underside of the leaves by spraying up. In contrast to Erysiphe necator, the false mushrooms do not feed on the nutrients in the Plant, but rather infect the cells directly and produce the characteristic ones through spore carriers Covering. The following symptoms arise in the event of an infestation:

• white, gray or slightly purple floury coating forms on the underside of the leaves
• The top of the leaf lightens and forms oil stains
• Leaves wither over time
• Plant can die completely
• Leather berries, grapes no longer edible

The leather berries are what winemakers fear, because the grapes die off completely when they are still young. They attack young bones of the grapevines, dry them out and harden the skin in the process. After the infestation, the berries act like raisins, which have an unhealthy color and are tough like leather. Because of downy mildew, as with real crops, entire harvests can therefore fail, which is devastating for viticulture. In contrast to powdery mildew, however, the wrong one is not as specialized and has about the same effect on a wide range of grape varieties:

• Müller-Thurgau
• Gutedel
• Portuguese
• Limberger

Note: Downy mildew fungi start to attack the wine from a temperature of over 11 ° C. That means that this starts quite early in spring, especially when the snow is gone.

Prevent powdery mildew

Before you have to treat the vines with a spray or household remedy, you should plant and care for the wine in such a way that the possible infestation is reduced or even prevented as much as possible. The fungi have the greatest potential for attack if the vines are in an unfavorable position or if the wrong nutrient addition or dosage is received. With the following 7 tips, you can ensure in advance that your wine is better protected from the fungi:

Tip 1. Give your vines enough space, because this is the only way the air can circulate between the plants. If you have plants near walls, make sure that they are far enough away. Recommended distance: between 100 and 200 cm.

Tip 2. Herbs between or near the vines provide protection against powdery mildew. Due to the active ingredients they contain, these act against the spores of the mushrooms. Above all, these include:

• chervil
• basil
• chives

Tip 3. Do not fertilize too much and avoid large amounts of nitrogen when fertilizing, which acts as a breeding ground for the mushrooms.

Tip 4. Make sure to protect the leaves from excessive moisture, especially rain. Too much water leads to an unbalanced microclimate between the leaves of the plant, which in turn restricts air circulation and increases the risk of fungal attack.

Tip 5. Water only in the morning or evening. To do this, only wet the location and the roots, not the trunks or shoots of the wine.

Tip 6. Weeds that are affected by powdery mildew and grow near the vines should be removed because the spores collect here. However, never dispose of this on the compost, as the spores could spread from there through wind and rain.

Tip 7. Regularly use strengthening brews, for example from field horsetail. These ensure effective growth of the plant, which becomes stronger from the inside out through the brew.

Although this does not guarantee that the wine will not be infested, these measures can greatly reduce the likelihood. Above all, fresh air and the right nutrient balance are important for the vines to keep them from growing You can even fight powdery mildew, because weakened plants are especially good for fungi delivered. However, if your wine is infected, you must first identify which fungus it is, as different treatment measures are available for the two species. Or as an alternative, plant grapevines that are truly powdery mildew resistant.

"Resistant" varieties

Wine is available in numerous varieties and some of these have been bred for several years for resistance to fungus in order to be able to counteract attack by powdery mildew fungi. This is especially important for organic viticulture, since no aggressive pesticides may be used here. These grape varieties all come from Europe and for the most part are powdery mildew resistant and are much better suited than the classic grapes that are typical for viticulture in Europe. American vines, for example, are powdery mildew resistant, but not so well suited for cultivation in Germany. You should choose one of the following varieties:

• Regent: red
• Cabernet Blanc: white
• Baron: red
• Reberger: red
• Muscat Bleu: red
• Villaris: white
• Felicia: white
• Cal 6-04: white

The Regent grape variety is particularly recommended here, as it has shown itself to be extremely resistant to powdery mildew and other fungal diseases in recent decades. If the location is optimally chosen and appropriately well fertilized, infestation by the fungi is almost impossible. The other grape varieties are also very suitable, especially with good care, and can save you a lot of trouble. The regent's harvest yield is also not without it. Please note that these vines can also get powdery mildew if they are over- or under-fertilized and too much moisture.

Fight powdery mildew

You can treat the grapevine disease either through chemical sprays or home remedies, which are much gentler. In your own garden you should avoid chemical agents at all costs, as they could not only endanger you, but also your neighbors, pets and wild animals. Remove infested leaves and shoots before each treatment in order to also contain the spread. You can fight the fungus by the following means:

• special sprays from the trade on an ecological basis
• Skimmed or raw milk
• baking powder
• Ablutions
• Herbal broths
• Bring beneficial insects into the garden

Ecological pesticides from the trade

There are more and more products on the market with which you can efficiently fight the fungi on your grapevines. These are not even harmful, as they are created on an ecological basis and thus literally tackle the problem at the root. The following manufacturers are recommended here:

• Compo
• Neudorff

These manufacturers are well-known in the horticultural industry and offer combats based on copper, which is effective against the fungi. These are administered via a conventional spray bottle according to the dosage information on the packaging and can even be used in the event of a severe infestation. It is important that you then dispose of the packaging in the recycling center.

milk

Skimmed and raw milk can be used quite well against an initial infestation. To do this, proceed as follows:

• mix 100 milliliters of raw or skimmed milk with 600 milliliters of water
• fill the agent in a spray bottle
• treat the plants extensively with the product every four days

The milk is particularly suitable for the initial stage of the infestation and acts as a precaution against the fungus, as the fats in the milk work against the spores.

baking powder

The baking powder solution is good for fighting powdery mildew because it contains lecithin and is so effective against the fungi. The mix is ​​created as follows:

• First mix together 10 ml of baking powder, 10 g of rapeseed oil and a drop of washing-up liquid
• then dilute the mixture with a liter of rain or mineral water
• put this in a spray bottle and spray the wine every ten to twelve days
• spray in the evening, as the solution can easily be absorbed here without reacting to the sunlight

Ablutions

Fight powdery mildew with targeted washing of the entire plant. Although the plants should not be kept too wet, it is worth hosing down with a garden hose that sprays mineral or rain water. You should then carefully dry the vines with a cloth. This is particularly useful for light infestations, but has to be repeated quite often.

Herbal broths

You can fight powdery mildew extremely well with herbal broths, as the ingredients work against the spores. Use medicinal herbs for this, for example: field horsetail, Canadian goldenrod, nettles, tansy or rhubarb leaves (not a medicinal herb, but still works). Proceed as follows:

• Chop 300 grams of the fresh or 30 g of the dried herb, the best is field horsetail
• soak this in 10 liters of water for twelve to 24 hours
• simmer for 15 minutes the next day
• dilute this brew in a ratio of 1: 5 with water
• sprinkle the vines every four days

Beneficial insects

As an alternative, you can also bring beneficial insects into the garden. Above all, ladybirds and sawfly were to be mentioned here, which feed extensively on the mushrooms. They also maintain the natural balance of the garden while you fight powdery mildew.