Content of the article:
Grapes, like any other plant, require full sunlight, sunshine, heat, water and nutrients,which he gets from the soil. With a lack of any of these components, the plant appears all sorts of diseases. Let's talk about such a frequent phenomenon as the lightening of grape leaves.
Why do the leaves turn brighter in grapes?
The phenomenon of rapid, within a week, lightening of the leaves is called chlorosis. With chlorosis in grapes, the leaves first turn pale and then turn yellow. This is due to the fact that the leaves are unable to produce chlorophyll. The leaves accumulate in excess carbon dioxide and hydrogen sulfide, which plants are not able to process.
There are many reasons for chlorosis of grapes:
- The lack of trace elements in the soil.
- Excessive lime in the soil.
- Soil salinity.
- Fungal diseases of the roots.
- Weather Conditions.
- Infectious diseases.
Cold and rainy weather contributes more to the development of chlorosis than dry and hot. With an increase in the amount of water in the soil, its aeration is reduced. Plants suffer from lack of oxygen, metabolic processes are disturbed in them, they stop branching and rot.
In addition, by dissolving lime in the soil, water can cause an alkaline reaction, in which minerals necessary for the grapes become insoluble compounds and carbonate chlorosis occurs in plants. You can compensate for the excess lime by the introduction of ammonium sulphate at the rate of 3 kg of the drug for 1 vine.
Fertilizers that cause alkaline reactions should not be applied to the soil:
- Fresh manure( especially poultry).
- Nitrate compounds of sodium and calcium.
- Large portions of superphosphate.
In areas with a high salt or carbonate composition of the soil, you can use grape seedlings grafted on rootstocks that are resistant to these adverse factors.
The lack of minerals
To date, there are about 70 trace elements necessary for grapes for growth and development. Lack of some elements and an excess of others can lead to serious violations of the health of grape bushes and, as a consequence, crop loss and even death of plants.
Light green color in vine leaves is often caused by a lack of minerals. Lightening leaves can cause a lack of nitrogen, manganese, boron, zinc, molybdenum, and iron in the soil.
Nitrogen is an element of growth. It is vital for plants, stimulating their growth and entering into the composition of proteins. Nitrogen is found in the soil in insoluble compounds and is therefore not available to plant roots. They receive active nitrogen mainly from organic humus, where this element is processed by soil bacteria into a soluble form. If there is not enough nitrogen in the soil, then the appearance of the plants immediately changes. Buds open slowly, shoots weak, without ovaries. On the grapes, the lower leaves become light green and their petioles turn red. Such leaves soon die and fall off. Shoots become thin, with frequent internodes. Leaves and berries are shrinking.
In order to ensure that grapes need nitrogen, in the spring, urea or complex mineral fertilizer containing nitrogen should be distributed in the bushes feeding zone.
Zinc affects the course of redox reactions in the body of plants, is involved in the conversion of carbohydrates. In addition, zinc is extremely important in nitrogen metabolism. With a lack of zinc in the tissues of the grapes accumulates nitrogen, disrupting protein synthesis. In this case, the leaves of the grapes lose their symmetry, become jagged, brittle, covered with light spots with a metallic sheen. The growth of shoots and hands weakens. Lack of zinc in the soil - a fairly frequent occurrence. Improve the situation to help foliar treatment of grapes with zinc oxide solution. A less effective means is to add zinc chelate to the soil.
The boron trace element is responsible for the reproductive function of plants. With a lack of boron, the leaves of the grape mosaically fade: in the intervals between the veins, the leaf tissue turns white, then turns brown and dies. The edges of the leaves are bent outward. The brushes on the grapes are either not tied at all, or they are tied weakly and at the beginning of flowering they fall off, the growing point dies. The roots weaken, which leads to winter freezing. To eliminate the boron deficiency, foliar feeding is carried out with boron-containing preparations.
Very rarely molybdenum may lack grapes. This deficiency makes its leaves pale and dull; turgor disappears in the leaves. Molybdenum is involved in water and nitrogen metabolism, affects the sugar content of grapes, its ability to root formation and wound healing. To compensate for the lack of molybdenum can be fertilized into the soil with this element, for example, molybdenum superphosphate.
The lack of manganese manifests itself similarly to the lack of trace element boron. The leaves of the grapes first become spotty: covered with small light green specks. In the future, the light areas increase, merge, turn yellow and die. Manganese is responsible for the regeneration of plant tissues, is involved in photosynthesis and the formation of grape juice, affects the absorption of nutrients. The lack of fill foliar treatment with manganese sulfate.
Grape diseases and its treatment
Clarification of vine leaves can also occur due to an infectious disease. Chlorosis is caused by a yellow( spotted) mosaic virus that is carried in the soil by nematodes. The virus may also be present on poor quality planting material.
The main sign of infectious chlorosis is that the veins first turn yellow, and only then the leaf tissue. On the leaf plates appear either individual yellow spots, or yellowness begins to spread from the veins. Over time, the leaves turn brown, curl and dry. The shoots have short knots - the nodes are located very often to each other, many of them grow with small leaves.
If the grapes were hit by a spotted mosaic virus, then it must be uprooted and destroyed immediately, otherwise there is a risk of infecting other plants( not just grapes).The soil in its place must be carefully sanitized against nematodes. Experts recommend for disinfection up to 6 years to grow crops at this place that do not eat nematodes, for example, cereals.
Under no circumstances should cuttings be taken for propagation from plants infected with a yellow mosaic! It is possible to restore a variety only with the help of a healthy planting material.
Fungal pathogens can also cause diseases of the vine. Its treatment consists in the timely treatment of plants with antifungal drugs. When powdery mildew( oidium) and downy mildew( mildew) are infected, the grape leaves are covered with yellow spots and ashy, like mold, with bloom. Under bloom on the leaves appear light spots. Powdery mildew contributes to warm, wet weather in winter and spring. These diseases can completely destroy the crop.
Therefore, during the care of grapes in June, it is necessary to carry out a threefold treatment of the bushes with antifungal preparations - in the second, third and fourth decade of the month. In parallel, you can handle bushes and against parasites. It is best to carry out the treatment in the evening when the sun is not so hot. Leaves should be covered with a solution on both sides. After the rain, it makes sense to recycle the bushes of grapes.
Annually it is necessary to change drugs for antifungal treatment, so as not to cause resistance to them in pathogens.
How to sprinkle grapes? Fungicides( antifungal agents) can be prepared both independently and by using industrial solutions.
You can make the following drugs yourself:
- Bordeaux fluid. The mixture is prepared immediately before spraying. To obtain a 1% solution, 100 g of copper sulphate powder is poured with 5 liters of hot water. To increase the concentration of the solution for every 1% you need to add 100 g of copper sulphate. For every 100 grams of copper sulfate take 75 grams of quicklime and quench it in 5 liters of cold water. Then lime is well stirred and filtered from the suspension. Continuing to mix, thinly pour in the solution of vitriol. The reaction solution must be weakly alkaline or neutral. If the acidity is high, lime should be added. Before treatment, the drug can be mixed with sulfur.
- California liquid ( lime-sulfur decoction).17 parts of water take 1 part of quicklime and 2 parts of sulfur. Sulfur is kneaded in the form of dough, and lime is quenched in the rest of the water. Then everything is mixed and cooked for 1 hour.
Do not inhale vapors of a hot preparation, as this may damage the respiratory organs! The result is a dark red liquid. Before processing the solution is diluted with water.
- Aqueous solutions of colloidal sulfur and ferrous sulfate .
The choice of industrial products is quite wide: Ridomil, Mancozeb, Acrobat MC, Ditan M-24, Rapid Gold, Atsidan, Cupricol, Ordan, Tsikhom, Topaz, Poliram, Alirin-B, Planriz, Fundazol.
Very effective feeding of grapes with ash . It can be applied either to the soil or used for foliar treatments. Ash is a good source of potassium and phosphorus and at the same time has antifungal properties.
For foliar feeding, 1 liter of ash should be soaked in 2 l of water and left for 3 days. Then add another 4 liters of water, after which the mixture will be ready for use. When ash is introduced into the soil, it should be dug into the grooves around the grape bushes. In the fall, bushes can be poured over with a solution of ash( 200 g per bucket of water), after pouring 3 buckets of water under each bush.
In order for your vineyard to be healthy and to delight you with an excellent harvest, no diseases, especially infectious diseases, should be allowed into it. And the first cry for help can be exactly the light green color of the leaves of the vine.