Grapes are one of the cultures that used to be considered exclusively southern. But now it is successfully cultivated not only in the south, but also in cooler regions. But in the south and in the center of Russia, where grapes are now grown, gardeners experience, in fact, the same problems, including such as shedding of the ovary. We will talk about the causes of this very unpleasant phenomenon and how to avoid shedding the ovary on grapes or stop this phenomenon.Grapes shed their ovaries for a number of reasons.
Natural dropping ovaries on grapes
So, the ovary of grapes sometimes crumbles, which is extremely negative for the crop. There is a massive shedding of the ovary on the grapes, usually within a week after the end of its flowering. During this period, the ovary sometimes manages to develop to a value equal to about three or five millimeters. Often, one can notice the shedding of flowers even before the formation of the ovary or even buds.
Often shedding of the ovary, buds or flowers is not catastrophic: both the ovary and the buds and flowers show off in small quantities, and this is a natural process of regulating the load by the crop, which is carried out by the plant itself. Simply put, the grape plant itself calculates how many berries can ripen without harming it, leaving this amount, and discards the remaining ovaries, flowers, or even buds. This fall of the ovary is observed in all cultures and it is especially noticeable in fruit crops, for example, in the apple tree.
But sometimes the ovary really falls in significant numbers, and then you can sound the alarm and put the plant clearly unsettled in order. There can be many reasons for the mass decay of the ovary on grapes.
Biological disturbances in the structure of the flower
Biological disturbances in the structure of the grape flower arise for a number of reasons. Usually these are viral diseases that violate the plant's vascular system, but there may also be disturbances in the development of individual kidneys. In the case of a viral infection, nutrients cannot normally move around the plant, the formation of buds, and, consequently, the flowers, is disturbed.
Blooming flowers can have an ugly appearance, and their organs, intended for the production of pollen or for the perception of pollen, become incapacitated or weakly susceptible to pollen. In this case, there may be a complete absence of pollination and dropping of buds or flowers by a plant of grapes, as well as setting berries, but the impossibility of their further development and dropping of ovaries.
Unfortunately, it is extremely difficult to cure viral diseases of grapes, it is often simply impossible to do, and gardeners prefer to simply uproot plants and remove them from the site. By the way, if the grape plant is really affected by the virus, then after removing it from the site in the same place, it is advisable not to grow grapes, because a viral infection can be in the soil for a very long time, up to seven years.
There are a lot of viral diseases of grapes; it can be short-knot, yellow mosaic, wood furrow virus, red-leaf virus and leaf-twisting virus. Any of these viral infections can cause both falling flowers and buds, and falling ovaries and inevitably leads to the death of the plant.Viral infections are one of the reasons for dropping the ovary with grapes.
Diseases and Pests
In addition to viral infection, grape plants can be damaged by pests and suffer from treatable diseases. Against pests, they use insecticides that are allowed in the current season, strictly following the instructions on the package. Against diseases, fungicides are also used, which are also allowed in the current season and always strictly following the instructions on the package. Treatments should be carried out in protective clothing, and carried out in the evening, so as not to cause burns on the leaf plates.
Of the diseases on grapes, the most common are: various leaf spots, oidium, powdery mildew and gray rot. Any of these diseases can cause the ovaries to fall due to weakened plant immunity and metabolic disorders in the tissues.
Of the pests on grapes are most often observed: various ticks, leafworms, willow woodworms and marble rags. All these pests can cause very serious damage to grape plants, disrupt metabolic processes, cause the discharge of ovaries.
The overhead mass of the bush grows too actively to the detriment of the crop
This phenomenon can be observed when there is a lot of moisture and nutrition in the soil, and the season is characterized by moderate warmth and excessive rainfall. Most often, under these conditions, it is young grape plants that can theoretically yield a crop, but they spend energy on the formation of a vegetative mass.
If this is the case, then one season can be patient and not take any additional actions. The next year, as a rule, grape plants give a good harvest.
Weak pollination, lack of pollen
In order to provide grape plants with enough pollen, experienced growers, contrary to general opinion and advice, never remove extra clusters precisely during flowering. Such a simple technique will provide grape plants with enough pollen, and the flowers will not fall. Only after the plants have flowered and the ovaries begin to form, can the extra ones be removed, giving preference to those clusters that have well-developed ovaries.
Lack of moisture in the soil
A moisture deficit in the soil, especially during flowering, the formation of the ovary and its growth, is almost the main reason that the ovary will inevitably crumble, sometimes in a very significant amount - up to 80% of the entire ovary on the plant. To avoid this, grapes must be watered. It is advisable to do this with room temperature water and carry out watering in the evening.
During the flowering period, it is not recommended to water the grapes by sprinkling, because such watering can disrupt the fertilization process, but after flowering and before flowering, you can water the plants, both under the root and sprinkling.
Before the flowering of grapes, the soil moisture can be maintained at a level of 50-60%, during flowering and after it, when the ovary is formed and develops, it is desirable to maintain soil moisture at a level of 65-70%, then shedding of the ovary will be minimal.Drop watering when growing grapes.
Lack of nutrition in the ground
If there is a lack of one or another element or group of elements in the soil, grapes can also drop most of the ovary or, if the situation is really critical, the ovary can completely crumble.
To avoid this phenomenon, you need to know the composition of the soil on which the grapes are cultivated. It is advisable to give the soil for analysis to the laboratory once a year in order to find out its composition and understand which element is in large quantity and which elements are clearly not enough, and based on this, decide on the introduction of one or another element into the soil.
If we talk about standard fertilizer for grapes in order to maintain the optimal combination of substances, then it is advisable to apply these fertilizers in spring time (late April), during the flowering period, immediately after flowering, and also during the period of active growth of the ovary of grapes.
In spring, under each bush of grapes, you can add a kilogram of well-rotted manure or compost, decomposing it on previously loosened and watered soil. During the flowering period, plants can be fertilized with nitroammophos, making it dissolved in water (15 g per bucket of water, the rate per plant).
Immediately after flowering and during the period of active growth of the ovaries of grapes, you can add potassium sulfate in dissolved form (10 g per bucket of water at a time, the norm for one plant) and superphosphate in dry form in previously loosened and watered soil (12 g under every plant).
If the ovaries of grapes are crumbled, then foliar top dressing can be done by dissolving 15 g of nitroammophoska in a bucket of water and treating the plants from the sprayer, wetting the whole aerial mass well. Also in this case, you can treat the plants with an aqueous solution containing boron and zinc.
Often it is the excess nitrogen that can negatively affect the ovaries of the grapes and cause them to shed. If you notice that the grapes are actively growing, forming a large amount of vegetative mass, large leaves and all this against the background of the fact that the plant is more than five years old, then, most likely, there is an excess of nitrogen in the soil.
With a strong excess of nitrogen in the soil, the leaves of the grapes acquire a dark green color and their tips can begin to curl. Solving this problem is quite difficult. The only way out is to try to neutralize the excess nitrogen in the soil by abundant watering or additional application of any phosphorus and potassium fertilizers.
Varietal plant features
There are grape varieties that are biologically prone to shedding the ovary, sometimes in fairly large quantities. Given this, in order not to take completely unnecessary actions in the future, you should find out in the nursery where you will get grape seedlings about the features of the variety you are purchasing.
In case the grape variety you purchased is characterized by significant shedding of the ovary, it is necessary to pinch the tops of all fruiting shoots. This simple green operation will stimulate the outflow of nutrients to the ovaries, reduce their shedding, and contribute to the formation of larger berries.There are grape varieties that are biologically prone to shedding the ovary.
Cold and damp or hot and dry weather
In cold and damp weather, as well as in too hot and dry weather, pollen deficiency, impossibility of falling onto the stigma of the pistil or immunity to pollination can be observed. In this case, shedding of grape flowers is more often observed, but shedding of the ovary can also be observed.
In order to maximize pollination in cold and damp weather, ensure that the vines are well ventilated. Be sure to periodically thin out the vines, cutting out the extra shoots, as well as an excessively active growing green mass and leaves that cover the flowers.
To increase the susceptibility of stigmas of pollen pistol, both in dry and hot weather, and in cold and rainy weather, it is necessary to spray plants with a solution of boric acid. For grapes, the solution is prepared as follows: you should take a tablespoon of urea, a tablespoon of boric acid, a teaspoon of iron sulfate and a third of a teaspoon of citric acid and dissolve in 10 l of water.
In order not to cause problems with the dissolution of the ingredients, first it is citric acid that needs to be dissolved in water, then all other substances. First, it is desirable to dissolve boric acid in 200 grams of warm water, and then pour this amount of liquid into a common container. With the resulting composition, you need to fill the sprayer and spray the flowers, moistening them well.
If it is not possible to sprinkle plants with such a composition, then grape flowers can be artificially pollinated. Artificial pollination will be most effective if carried out in the early morning or in the evening. You can pollinate plants with a down glove, gently touching each flower.
Conclusion We described the maximum number of possible causes of shedding of the ovary on grapes, if you know about other reasons, then describe them in the comments, this will be useful to all readers.