Oidium On Grapes: How To Treat, Comprehensive Control Measures

Oidium is a fungal disease that affects grapes. On other crops this disease is known as powdery mildew (not to be confused with peronosporosis or false powdery mildew), or peplica. The causative agent of this disease is Oidium Tuckeri Berk, it came to Europe from North America, and it was first discovered in 1845 by horticulturist Tucker in England. Only 5 years later, Oidium has already spread throughout European territory. The vineyards in France were especially badly damaged by this disease, and were only saved because a highly effective agent against Oidium was found: sulfur.

Properties of the disease

Oidium on grapes: how to treat, comprehensive control measures

In the springtime, when vine stems begin to grow actively, you can find growths on the bush that are behind in development. The foliage opening on such growths is curly and its surface is partially or entirely covered with a whitish-gray patina. By June, this plaque can be found on both upper and lower surfaces of leaf plates, and inflorescences, upper parts of stems and bunches look as if they were sprinkled with ashes or flour from above. Then the diseased inflorescences die off, and the diseased fruits wither away. Pea-sized berries crack and also drop off when hot or dry.

Almost all European varieties of grape are subjected to Oidium. Incubation period (time from infection to fungal growth) is 1-2 weeks. Mycelium growth is most active at the air temperature of 25 to 30°C, but it is still active even in cooler temperatures. It spreads very quickly if the plants are too dense (due to poor ventilation) and if the leaves are very numerous.

Mildew or oidium

Oidium on grapes: how to treat, comprehensive control measures

As mentioned above, grape oidium is powdery mildew, while grape mildew is either false powdery mildew or peronosporosis.

These diseases are very different from each other, and they are caused by different pathogens. What they have in common is that both of these diseases are fungal, and that they can kill almost the entire grape crop. The signs of these diseases are also very different from each other. A detailed description of the symptoms of oidium can be found above. If mildew is found on grapes, pale yellow oily spots appear on the front surface of their leaves; after dew or fog, a coating appears on the underside of the diseased leaves, turning brown after a while and drying out.

Most often mildew affects young leaves as well as inflorescences which become fulvous, stems (with black spots) and unripe fruits (they become dark around the stalk and fall off). If the grapes do not fall off, they will still have a sour taste. If the vines have fully ripened fruits by the time mildew occurs, they will not suffer.

Oidium control measures

Oidium on grapes: how to treat, comprehensive control measures

To save a vineyard from oidium you must resort to a whole complex of measures that includes: prevention, agronomic rules, folk remedies and chemical preparations. Specialists recommend to treat plants against mildew as well, while fighting against oidium.

Preventive measures against these diseases are the same. But to spray the bushes, it is recommended to choose special combined chemicals which include both sulfur used to control oidium and an organic fungicide or copper used to control mildew.

Oidium on grapes. Causes of infection and methods of control

Chemical treatment

If grapes were affected by Oidium during the last vegetation period, treatment against it should be made as early as possible. But when spraying the bushes with sulfur it should be taken into account that the drug will be effective only if it is not colder than 20 degrees outside.

The fact is that for hard sulfur to work, it must pass into a vaporous form, and this only happens in the warmth (not below 20 degrees). On hot days, treatment should be carried out in the morning or in the evening (after 16 hours), otherwise burns can form on the surface of the leaves. Spray the bushes 3-6 times with 1.5-3 weeks interval. After treatment, inspect the leaf plates; there must be a thick layer of sulfur on both surfaces.

If the sulfur is wet, it can no longer be used to control oidium.

Prophylactic spraying of grapes involves the use of products such as: Caratan, Talendo or Switch. And already diseased bushes are treated with both colloidal sulfur and the following highly effective fungicides: Skor, Tiovit Jet or Horus. It will not be possible to cope with oidium without chemicals, but the negative impact on the plant of toxic chemicals can be minimized. In order to do this, systematic preventive measures must be taken.

Preventive measures

Oidium on grapes: how to treat, comprehensive control measures

However, regular preventive spraying in most cases prevents grapes from being affected by fungal diseases. However, note that prophylactic solutions contain 3-4 times less active substance than solutions of fungicide agents used during treatment.

Oidium prophylactic treatments begin in late fall, when preparing the bushes for wintertime. At this time they are sprayed with a solution of copper or iron sulfate, which can destroy the remains of the fungus. Before the buds swell, in early spring, bushes are sprayed with a solution of Azofos (it is done exactly according to the instructions on the package).

This product contains nitrogen, which contributes to the effectiveness of copper. Before the plant flowers, it is sprayed with a solution consisting of 1 ampoule of Topaz, 2 sachets of Ridomil Gold (weighing 10 grams), 40 drops of Ecosil and 8 liters of water. Then, the bushes are treated during the formation of berries, using in this case the same solution, but Ridomil is replaced by Ordan. Then plants are treated regularly against mildew and other diseases, but these procedures may well prevent the development of oidium. Make sure that throughout the season, fresh air is available for each shrub, on all sides.

It is also very important in preventing Oidium that the soil in the vineyard is well aerated.

Oidium Treatments (fungicides)

Oidium on grapes: how to treat, comprehensive control measures

The following pesticides are described below for treatment or prevention of Oidium on grapes:

  1. Azophos. This new generation product is used in the fight against fungal diseases and is environmentally safe.
  2. Iron vitriol. This broad-spectrum product has been used for the treatment of fungal diseases for a very long time.

    It should not be used in conjunction with phosphorus-based products.

  3. Copper sulfate. A broad-spectrum contact agent containing copper is quite effective in the treatment of fungal diseases.
  4. Caratan. This contact preparation has a narrow therapeutic and preventive action; it helps suppress the growth of pathological fungi that cause the development of oidium.

  5. Colloidal sulfur. This pesticide has been used by horticulturists for a long time; in its vapor state it is excellent for suppressing fungi that contribute to the development of various fungal diseases, and it is also capable of exterminating mites. The product can be combined with almost any other fungicide.
  6. Ordan. This contact-system agent is used to treat fungal diseases of grapes.

  7. Ridomil Gold. This contact-systemic agent is effective in controlling fungal diseases.
  8. Scor. This systemic product is very effective in the treatment and prevention of powdery mildew, phytophthora, scab, leaf curl and other diseases.
  9. Tiovit Jet.

    This contact fungicide and acaricide is used to prevent mites and powdery mildew.

  10. Topaz. This systemic drug is quite effective in the treatment of fungal diseases.
  11. Horus. A systemic topical drug used in the control of fungal diseases.

  12. Switch. The systemic topical drug is used to treat and protect plants against diseases caused by various fungi.
  13. Talendo. A relatively recently developed preparation that is quite effective in preventing fungal diseases.
  14. Ecosil.

    This product regulates plant growth and has fungicidal properties and is used to strengthen the defenses of grapes.

Remember to spray your bushes with pesticides at least a couple of months before harvest.

Simple, Reliable OIdium Treatments for Grapes! SAFE PREDICATE AT THE PLUGGING TIME!

People's cures for grape oidium

Oidium on grapes: how to treat, comprehensive control measures

If you do not like treating grapes with pesticides then you can try using less toxic folk remedies. For example:

  1. Rake up grass cut beforehand into a pile and wait until it starts to turn grey due to mold. It is then put in a bucket in which water is poured.

    Mix everything well and strain. Such a remedy is used to regularly spray the vineyard throughout the spring and summer.

  2. Mix 7 litres of wood ash with 5 litres of water, the infusion will be ready after 24 hours. The strained remedy is diluted with so much water that its volume increases a couple of times. Dissolve 100 grams of green soap in it, and then treat sick plants with it.

    Instead of infusion, the solution can be boiled over low heat for a third of an hour.

  3. Water is combined with straw chaff in the proportion 3:1, the mixture is left for 3 days for fermentation. The strained infusion is diluted with water until its volume increases 3 times.
  4. With a bucket of water add 2 to 3 kilograms of cowpea, the infusion will be ready after two to three days. It should be strained and combined with 1 tsp.

    of urea. When treating grape leaves, they should be soaked on both sides.

  5. A bucket of water is added with 5 grams of manganese potassium. The solution is used to spray the vineyard.
  6. Combine a bucket of water with a liter of milk or whey, stir everything well and spray the bushes over the leaves.

  7. Combine a bucket of water with 30-40 grams of soda ash and 40 grams of dishwashing liquid.

Oidium-resistant varieties

Oidium on grapes: how to treat, comprehensive control measures

Till today there is no grape variety that is not affected by Oidium. However, there are varieties which are very resistant both to Oidium and to other diseases caused by various pathogenic fungi.

It has already been said above that all European grape varieties are least resistant to powdery mildew. Most resistant to Oidium was found such variety as Vostorg, and hybrids created on its basis: Talisman, Vostorg oval (Baklanovsky), Vostorg ideal, Gift of Zaporozhye, Timur, etc.

Also high resistance to all fungal diseases including oidium and such grape varieties as: Victoria, Kishmish Zaporozhsky, Galbena-now, Alexa, White miracle, Muscat velvet, Platov Jubilee, Gift of Ukraine, Pink Timur, Matryoshka, Denal, Golden Don, Lark, Caucasus and Sashenka. And still rarely affected by Oidium varieties created on the basis of species - Vitis labrusca, for example: Alden, Alwood, Fredonia, Isabella large-fruited, New York Muscat, Pocklington, Supaga, Juodupe, Mars, Venus and Ainseth Sidlis. There are also varieties that are resistant to a range of diseases, including fungal diseases. Such varieties include: Marinovsky, Platovsky, Crystal, Harmony, Millennium, Amethyst Novocherkassk, Lancelot, Beautiful Flora, Kishmish Klyuchikova, Pleven, Eurostandard, Bogotyanovsky, Archny, Antony the Great and Hope AZOS.


ODING during berry ripening


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