Chlorosis on grapes
Grapes are among the whimsical crops. Today it can bloom with a beautiful green color, and after a few rainy days the grapes can change their color to yellow. This is what may indicate the presence of such a disease as chlorosis of grapes. But don't panic right away. This problem can be easily solved in a few days. In this article, you can learn about this disease, its causes, methods of treatment and prevention.
What is grape chlorosis?
Chlorosis of grapes: photo
Chlorosis of grapes is a condition when a plant is disturbed and the process of chlorophyll formation and at the same time there is a decrease in the activity of photosynthesis. The external manifestation of this disease is a change in the green color of the leaves and shoots to lemon-yellow or pale, and sometimes completely colorless.
Chlorosis of grapes: causes of occurrence
Chlorosis of grapes: photo
The causes of chlorosis in grapes can be both infectious and physiological in nature. The appearance of yellow spots on the leaves can be signs of diseases such as powdery mildew, rubella and a number of other diseases. But in most cases, this phenomenon is not associated with the presence of any specific disease. The non-infectious factor in the appearance of chlorosis is associated with the following:
- Lack of minerals in the soil, most often there is not enough iron (for prevention, you can use antichlorosin).
- Soil condition
- Large amount of rainfall, while drainage is poor. Moisture accumulates, which leads to adverse consequences.
Chlorosis of grapes is caused by various external conditions:
- Low temperature.
- Soil salinity.
- The access of oxygen to the roots decreases due to the high level of soil moisture (this is possible if the summer was rainy)
- The soil contains an insufficient amount of minerals necessary for the development.
Most often, the occurrence of chlorosis in grapes is associated with a deficiency of iron, nitrogen and manganese in the soil. what are the symptoms of chlorosis due to these reasons.
- most often, iron deficiency can be observed on young shoots. The leaves begin to fade and fall off. At the same time, the formation of new ones is not observed. The plant begins to take on a depressed appearance. Even if there is enough iron, but the soil is carbonate, iron cannot be absorbed, and also if there is an excess of manganese in the soil. Also, if there is a large amount of copper in the soil, then the same symptoms may appear as with a lack of iron.
- Manganese is an important contributor to the synthesis of chlorophyll. If there is a lack of this substance, then this can also cause chlorosis. Symptoms are similar to those that occur with iron deficiency.
- If the plant is deficient in magnesium, then the growth and development of the plant is impaired. A distinctive symptom of the presence of this disease is marbling. You can notice the presence of this disease on old foliage at the end of June. If you do not start control measures in time, then the foliage can completely fall off.
- If the plant is deficient in nitrogen, then the growth of the plant begins to slow down, the foliage acquires a pale green color. Infection begins with old organs and spreads to young ones. It may appear if you apply a large amount of organic fertilizers.
Varieties of the disease
Chlorosis of grapes: photo
Before you start treating grapes for this disease, you need to understand what caused it.
- Infectious. A disease is caused by a specific virus. A symptom of a virus is the appearance of leaf discoloration, and it starts from the veins, at first of a small size, therefore it moves to larger ones. The color change begins with older leaves, then spreads to young foliage. But at the beginning of the flowering period, the grapes return their color. But this affects the size of the berries and bunches - they become much smaller. If the presence of the disease is confirmed, then this bush will have to be dug up, since the virus cannot be defeated. Virus infection most often occurs on grafted seedlings.
- Non-infectious. This factor does not depend in any way on infection with some kind of virus. Chlorosis can appear as a result of adverse external factors. In some cases, this is associated with the calcareous quality of the soil, which is associated with a violation of the nutrition of mineral elements. In this case, a change in the color of grape leaves occurs in areas that are located at a distant position from the veins, retaining the color of green, or otherwise discoloration in them appears in the latter case.
- Carbonate. Another name for the cause of chlorosis is calcareous cause. Development takes place in calcareous soil, which contains a large amount of lime, and also if heavy soil is present on the site. The soil contains a sufficient amount of iron, but at the same time the plant is not able to assimilate it. If treatment is not started on time, then the disease begins to spread from the foliage to the entire bush as a whole. due to the fact that a sufficiently large number of stepchildren are formed, the grapes begin to acquire a bushy state. If the bush is already badly damaged, then its death is inevitable.
How and how to treat chlorosis of grapes?
Most often, the fight against this disease must be carried out depending on the causes of the onset of the disease, as well as depending on the type of soil.
- Damp soil - be sure to lay drainage to avoid stagnant moisture.
- Alkaline soil - plant varieties that have good lime resistance.
- Light sandy soil - apply slurry, which must be diluted with water (1: 2).
In case of iron deficiency, it is necessary to prepare the following top dressing: the leaves must be sprayed with 1% ferrous sulfate, and the best option would be to use iron chelate (antichlorizin). You can buy a ready-made mixture in the store, or you can prepare it at home. To do this, you need to take citric acid (7 g) and ferrous sulfate (10 g) and dilute in 10 liters of water. It is also important to carry out root dressing. In autumn or spring, you can add iron vitriol (200-400g) under each grape bush. If the plant is deficient in manganese, then manganese sulfate can be used. In order to neutralize lime in the soil, you can use a solution of sulfuric acid with water (1:20). In this case, the acid must be poured into the water (not vice versa). The resulting solution can be applied under each grape bush for 5 liters. but you don't need to wait for the result right away. The first effect of using this method can be seen only after about 2-3 years.
If you find chlorosis on grapes, then there is a procedure that is suitable for any kind of it:
- Conduct a thorough examination of the bush in order to 100% exclude the presence of a virus (an infectious cause of the onset of the disease). most often, chlorosis can be seen on several bushes at once.
- After detecting the disease, you are determined with the nature of chlorosis (infectious or not). To determine this, look at the veins, whether they are affected or not. If they have retained their green color, then the causes of chlorosis are physiological and will be easily eliminated.
- Try to determine the deficiency of which element is present in the plant. You can understand this by the external state of the plant, but it is better to seek help from specialists, to a special laboratory.
- If this cannot be done, then a test spraying can be done. If you notice that after such a procedure, the condition of the bush has improved significantly, then you are on the right track.
Preventive measures against chlorosis of grapes
A better preventive measure against chlorosis of grapes is to plant varieties that have good resistance to lime and low soil acidity. Those grape varieties that are grown on calcareous soil use special columns. Next to the bushes, trenches are made, which have a depth of 40-45 cm and a width of 25 cm. Then fill such trenches with soil that does not contain lime, and add on top with the soil that you took out when building the trenches. Thanks to such columns, small roots are able to receive elements important for development in a fairly easy and digestible form. Also, for prevention, you can spray with antichlorosin or ferrous sulfate (3-4 times during the season).
The most resistant grape varieties against chlorosis
The following varieties can be planted that have good resistance against this disease:
- Pinot Aramon.
But at the same time, you need to pay attention to the fact that the variety you have chosen has good resistance to other diseases.
As you can understand from the above, most often the cause of this disease is a deficiency of a specific trace element. Therefore, the disease can pass on its own. If the weather is rainy, then after a while, the soil will warm up again and the plant will be able to recover. If there is a deficiency of the mineral, then fertilization can be applied. If the reason is the wrong composition of the soil, then you will not be able to do with fertilizing. Spraying and other methods are needed to help improve soil conditions.
Chlorosis of grapes: treatment