What are the dangers of autumn frosts for blackcurrants. The impact of frosts on the national economy

Spring (they are also called return) frosts can cause irreparable damage to fruit crops, even more than long winter frosts. While the plants are dormant, they are able to cope with prolonged low temperatures, but from sudden spring frosts, young shoots, leaves, buds, flowers, ovaries die.

plant sensitivity to sharp declines temperature directly depends on the stage of bud break - the stronger the buds have developed, the stronger the damage will be. For example, a blossoming bud dies about - 3.5 o C, -3 o C will be fatal for buds, a blossoming flower can no longer withstand - 2 o C, at the stage of completion of flowering, when the petals are already falling, -1.5 o can be fatal C, the ovary dies at -1 o C.

Frost-damaged flowers turn black in the middle; fruits will no longer develop from them. Rusty spots and thickenings appear on fruits damaged by spring frosts. If the ovary touched by frost does not die, then the fruits that develop from it are deformed, have a non-marketable appearance, although they are quite edible.

Raspberries and blackberries practically do not suffer from spring frosts, as they bloom relatively late. But such fruit trees and shrubs like black currant, gooseberry, red currant, cherry, apple, pear, plum, apricot are extremely sensitive to spring frosts.

Image source https://utahpests.usu.edu, http://ucanr.edu/blogs, https://ask.extension.org, https://www.flickr.com - JohnPaul Stainton

spring frosts

It has long been known that most fruit trees, being in a state of deep dormancy, are able to endure quite low temperatures. But after the start of active vegetation, their frost resistance is significantly reduced. Buds, flowers, ovaries are damaged by spring frosts, and we are frustrated by irregular fruiting or low productivity of our garden, complain about the weather or the environment, forgetting that sometimes we ourselves are to blame for the loss of the future harvest.

Frost resistance depends on the phase of flower development, with buds being more resistant than frost-bitten flowers or ovaries.

There are three types of spring frosts that damage orchards: adventitious, radiation, and mixed.

Adventive frosts occur as a result of the invasion of cold air masses from the northern regions, are accompanied by strong cold winds and last for several days. Protecting the garden from such a frost is difficult. AT southern regions such frosts have time to pass before the flowering of fruit crops.

Most often, significant damage to gardens is caused by radiation frosts, which are caused by local radiation of heat into space. They are observed on calm nights with a clear, cloudless sky.

Mixed frosts, the most dangerous for fruit crops, may also occur, which cause the greatest cooling, freezing of flowers, ovaries, and annual growth.

The location of the garden is of great importance. In low places, beams, hollows, the temperature is always several degrees lower than in elevated areas and on slopes. Here, fruit crops are more likely to suffer from low temperatures.

Methods for protecting ovaries and flowers are recommended differently, but, above all, smoking. Always with the beginning of flowering, a cold snap begins, frosts are also possible, which are very dangerous on those days when the whole day is hot weather, no precipitation and no clouds. It is in this case that radiation frost is possible. In stone fruit ovaries, already half a degree below zero can cause shedding. Spend the day before watering the aisles of the garden, sprinkle the trees with Novosil (3 ml). But the most important thing is to organize smoking, especially in the morning. The danger of damage is very high precisely during sunrise. At this time, the temperature drops sharply, and smoking should be carried out until 9 o'clock in the morning. Therefore, your site should have at least 10-20 smoke piles, evenly spaced throughout the garden. Preference should be given to the most tender trees and abundantly flowering cherries, and in the south - peaches, apricots.

Let's offer one more physiological method of protection - containment of the beginning of flowering. It is achieved by early spring irrigation, which lowers the air temperature and increases its humidity. For reference: irrigation delays the flowering of pome crops up to 7, stone fruits - up to 8 days.

Double treatment with Novosil before flowering prevents frost damage to flowers and ovaries, and after flowering it contributes not only to the formation of good ovaries, but also to better wintering of trees in the subsequent wintering.

Smoke reduces the radiation of heat from the soil and plants, thereby protecting the lower layers of air from cooling. Smoke should be continued for another 1.5-2 hours after sunrise, as it contributes to a slower, gradual thawing of frost-bitten flowers and thus preserves the possibility of their further development.

Spring frosts tend to repeat several times in a row, and therefore, after each night of smoking, the smoke piles must be restored. When the threat of frost has passed, the unburnt heaps are used as fertilizer or as mulching material.

K. Preobrazhensky , Ph.D. Sciences

spring frosts -frequent "guests" in the central regions of the European part. They do not happen every year, but if they do, then the damage is done in agriculture significant. Both flowering plants and tender young shoots suffer. Frost protection uncomplicated, but sometimes significantly helps to preserve the future harvest.

What are freezes?

Frosts are those infrequent drops in temperature below zero in the evening, morning or night hours at positive temperatures throughout the day. The temperature usually drops at the level of the soil, or in the lowest subsoil air layer.

When do freezes come? Causes of the phenomenon

Most often, temperature drops occur in May - early June.

It is noticed that the early melting of snow and the early arrival of spring entail May frosts in most cases.

Night frosts usually occur with the arrival of anticyclones. Associated with intense cooling of the soil against the background of a weak movement of air masses. This is facilitated by low humidity, lack of cloud cover. Especially often this kind of frost occurs in the lowlands.

If colder air has come (for example, the invasion of arctic air), then frosts can occur not only at night, but also at any other time of the day. Cold weather in May is not a rare occurrence, and is not necessarily associated with frosts, as evidenced by the popular proverb: "May is cold - a fertile year."

Frost protection - who and how do they harm?

flowering fruit and ornamental plants in our gardens are able to withstand light frosts. But if they are long - more than 4 hours - then damage is inevitable.

Some plants withstand temperature drops quite significant. Among the champions are beet shoots. Sugar beet is affected when the temperature drops below -6 ... -7 degrees. But most plants do not have such resistance, so it is necessary to organize protection. How can I do that?

• Smoke screen. If the frosts of the first type are associated with intense heat radiation from the soil, then by creating a smoke screen, we thereby reduce its intensity.

• Covering materials. They essentially do the same thing - the soil does not give off heat as intensively.

• Watering. Irrigation is an effective remedy. Especially for the protection of undersized plants. does not allow the temperature to drop to critical values.

• Covering hilling. This is the most win-win way to protect potato seedlings from freezing.

What are gardeners most afraid of in spring? The fact that during the flowering of garden trees and shrubs, spring frosts will suddenly strike, and the future crop will die. We plant heat-loving garden crops in greenhouses, make shelters for them. But what about bigger plant protection? And most importantly: is it possible to somehow predict cooling and frost without relying on the weather forecast?

During frosts, the apical point of growth is damaged in plants, which further leads, for example, potatoes and tomatoes to late blight disease. In cabbage, during frosts, instead of one healthy head, several small heads of cabbage are formed, pumpkin crops die, in apple trees, cherries, strawberries and even currants, flowers and young ovaries are damaged. Damage is stronger in lowlands, in drafts and in dense plantings.

Critical air temperatures for the garden in autumn, winter and spring

A sign of the onset of night frosts in spring and early summer is a sharp cooling in evening hours and clear skies bright stars. On such evenings at 21-22 o'clock it is necessary to check the readings of two thermometers: one dry, and the other wrapped in a damp cloth. If the readings turn out to be approximately the same as in the table below, then at night or in the early morning hours there will almost certainly be a frost.

Dry and wet bulb readings indicating upcoming frosts

How to protect your garden during frost

Are you worried about the thermometer readings? Then take a hose or a sprayer and water the garden well in the evening on the eve of freezing by sprinkling, spraying the crowns of trees not only outside, but also inside. Also spray shrubs, strawberries, vegetable gardens, flower beds, and the outside of greenhouses.

When sprinkling garden air humidity around the plants increases. During freezing, frost forms from moisture droplets, the process proceeds with the release of internal heat, and the temperature around the plants rises by 1-2 degrees. Moist soil well passes heat from the lower layers, so it cools slowly, which is also important, since frost goes through the soil.

Another completely reliable way to avoid the effects of frost is plant shelter any available material. In order to save the buds, flowers and ovaries from damage, it is enough just to cover the bushes from above. The garden can be covered with lutrasil or just newspapers.

In greenhouses, plants need to be additionally covered with either lutrasil or newspapers, or put arcs and make additional cover with a film. Such a double film cover will create the effect of a thermos: a layer of air between the two films will keep the temperature more or less constant, and in the heat the plants will not overheat, and in the cold they will not freeze.

At night, many gardeners light electric (100 watt / hour per 10 m2) or kerosene bulbs in greenhouses. The lamps must be covered with a cap so that the glass does not burst from the drop.

When the temperature drops to zero in the greenhouse at night, you can put just two buckets with very hot water, but not on the soil, but on a wooden stand so that the water does not cool down too quickly.

And further: folk omen- there will be no more frosts if the cuckoo cuckoos regularly, the red mountain ash has blossomed, and a white lily leaf has appeared on the water.

How to calculate flowering time

If you do not live in the country in spring and early summer, during the flowering of trees and shrubs, then you cannot know exactly when, say, cherry blossoms will bloom - and whether flowering will coincide with cooling and frost. But the timing of flowering can be calculated.

Below I give the average statistical data on the beginning of the flowering time of various horticultural crops for Leningrad region in which I cultivate my plot. You ask: why are they needed, because the timing of flowering of the same plants will vary significantly in different regions of the country? Yes, and temperatures current year may differ from the average data...

However, it has been noticed: the sequence of flowering shrubs and trees in the garden is very stable, therefore, taking some phenomenon as a starting point, for example, the flowering time of the coltsfoot on your site, you can very accurately determine the flowering time of other crops.

Calculate the number of days from the table between the flowering of the coltsfoot and, for example, currants. Get 40 days. Suppose your coltsfoot bloomed on April 20, which means that the currant will bloom in 40 days, that is, on June 1. If in your region the coltsfoot bloomed on April 8, then you can be sure that the currant will bloom on May 18. So, based on the above table, you can make a similar one for any region of the country.

Average statistical data for the beginning of flowering plants for the Leningrad region
Transition average daily temperature after 0 °С 1.04
Flowering coltsfoot 15.04
The transition of the average daily temperature through +5 °С on 29.04
Blossoming currant, birch, mountain ash buds 2.05
Last frost in the air 9.05
Cherry blossom 12.05
The transition of the average daily temperature through +10 ° С 17.05
Gooseberry blossom 20.05
Last frost on the soil 24.05
Currant blossom 25.05
Cherry blossoms, plums 26.05
Apple blossom 29.05
Strawberry blossom 3.06
Lilac blossom 4.06
Blooming red rowan 6.06
The transition of the average daily temperature through +15 ° С 10.06
Raspberry blossom 18.06
Ripening strawberries 25.06
Currant ripening 22.07
The transition of the average daily temperature through +15 ° С 31.08
First frost on soil 19.09
The transition of the average daily temperature through +10 °С on 27.09
First frost in the air 9.10
First snow 12.10
The transition of the average daily temperature through +5 ° С 21.10
The transition of the average daily temperature through 0 ° C 18.11

Author Galina Kizima Enthusiast gardener with 50 years of experience, author of original methods

Comment on the article "Frosts and the garden in spring: protection of plants during flowering"

Frosts and the garden in spring: protection of plants during flowering. However, it has been noticed: the sequence of flowering of shrubs and trees in the garden is very If the coltsfoot bloomed on April 8 in your region, then you can be sure that the currant will bloom on May 18.

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Blackcurrant in the country ... What does a novice gardener need to know about her? How to grow blackcurrant in the country? This berry shrub is widespread in almost all regions of our country because of its tasty and healthy fruits. Blackcurrant can be grown without any difficulty in sandy loamy soil that retains moisture well and is drained. It does not tolerate heavy clays, but can produce good yields on all types. wet soil provided that it contains a sufficient amount of organic matter.

It should be noted that chokeberry when grown requires a lot of nitrogen, prefers soil with acidity - pH range from 6.7 to 7, can not stand acidic soil. In addition, it gives a small yield if grown in places open to the winds. This plant has the ability to tolerate temperatures down to -20°C. But the flowers are damaged when the temperature drops to -1°C. Fruits with such damage are not tied.

Blackcurrant in the Kuban begins the growing season very early. The kidneys wake up in early March. Flowering takes place in the first or second decade of April, when the air temperature exceeds +8-10°C and lasts 7-12 days. It depends on the characteristics of the currant variety, weather conditions. Flowering may be shifted to earlier or late dates for 8-15 days.

The good preservation of flowers and their pollination is one of the important conditions getting a harvest. Black currant flowers correct form bisexual, with five-parted calyx, five petals, five stamens and pistils. Fertilization occurs when pollen from bursting anthers gets on the stigma of the pistil. Productivity depends on normal pollination. Very often, currants bloom profusely, but there is no harvest. The ovaries fall off 2-3 weeks after flowering, that is, fertilization does not occur. What is the reason?

It turns out that currant varieties are self-fertile and cross-pollinated. Self-fertile are well pollinated by their own pollen or pollen from their varieties. Although the variety is self-fertile, cross-pollination is also possible. Moreover, with cross-pollination on self-fertile bushes, large berries are obtained, and the yield is higher.

Self-infertile varieties (cross-pollinated) are not pollinated by their own pollen. They are pollinated only by the pollen of other pollinating varieties. They need certain conditions: the presence of pollinator varieties planted nearby, the attraction of bees and other pollinating insects. To do this, during flowering, it is necessary to spray the bushes with a honey solution (100 g of honey per 1 liter of water). The aroma of honey attracts bees, bumblebees, and other insects that work even in windy weather. This contributes to better cross-pollination of flowers, tying berries.

For full pollination, spraying flowering currant bushes with a solution of potassium permanganate 1.5 g + boric acid 1.5 g per 10 liters of water is also effective. Very important for garden plots have self-fertile varieties that are able to pollinate, set berries under adverse weather conditions during flowering. All varieties of chokeberry ripen in June. Only very late varieties sometimes ripen in the first decade of July. The weather conditions for growth, ripening of berries in May-June are quite favorable, that is, the harvest depends on the gardeners, on their care, protective measures on their plots.

Most varieties of blackcurrant are highly winter-hardy, withstand frosts of 40 degrees, even lower, the buds are not damaged. But during the period of its flowering in the Kuban, adverse weather conditions often develop: rainy, windy weather, which makes it difficult for pollinating insects; low positive air temperatures during the day; return spring frosts at night, in which damage occurs to flowers, young ovaries in unstable varieties.

To increase the resistance of currants to such adverse conditions, it is necessary to prepare the bushes in the fall. For digging or loosening the soil, phosphorus-potassium fertilizers and ash should be applied. If autumn is dry, irrigate. Plant several varieties. Next to low self-fertile varieties, place their pollinating varieties. Instead of varieties that are resistant to spring frosts, for example, Belarusian sweet, plant highly resistant varieties that can withstand temperatures drop to -5 ° C during flowering. Such varieties were bred by Russian breeders, there are many of them in the Kuban. Here are some of them: Altaiyanka, Grape, Dobrynya, Izyumnaya, Lyubava, Nara, Gift to Kuminov, Sevchanka, Selechenskaya-2, and others.

Black currant belongs to winter-hardy berry plants. New varieties bred with the participation of Siberian wild species, have higher winter hardiness. It tolerates a decrease in air temperature to -40 ° C and below. In the conditions of the Kuban, currants do not suffer from frost or low temperatures, but from its fluctuations in winter. That is, when the air temperature first rises to +10°C degrees, and then drops sharply to -10°C and below. From such temperature drops, freezing of the rudiments of flowers in mixed buds can occur.

During the flowering period, currants suffer from recurrent spring frosts in some years. Its vegetation begins at a temperature of +6°C, and in some varieties at +2°C. Optimum temperature for the growth of bushes + 18-22 ° С. In hotter weather, their growth slows down or even completely stops.

Where to plant blackcurrant in the country? When grown, chokeberry is quite demanding on lighting conditions. In the shade, it gives a very low yield, more damaged by diseases and pests. But new shade-tolerant varieties have been developed that grow well and bear fruit in shaded places. So when choosing a place for planting currants in the country, be guided by the characteristics of your variety.

In the Kuban, blackcurrant does not tolerate heat, dry air, strong solar radiation, especially in July-August. In extreme heat, dry weather, the leaves begin to burn from the edges, the tops of the bushes in many varieties can completely dry out. The root system in the heat suffers greatly from overheating of the soil, lack of moisture. Its active activity is sharply reduced, small roots in the upper soil layer die off or dry out. Currant bushes are attacked by pests, diseases (aphids, mites, powdery mildew, others). At the same time, there is a bookmark, the formation of buds on the shoots. Naturally, without the intervention of gardeners and summer residents to reduce the impact of adverse weather conditions on the life of bushes, very few buds form on the shoots, they are weak, the next year's harvest is low.

To reduce soil overheating, preserve the root system, leaves from drying out in July-August, it is necessary to systematically water the bushes, mulch the soil with any materials (humus, straw, grass, cardboard, etc.). It is necessary to use natural protection from hot rays, place currant bushes in partial shade behind buildings, trees, so that at lunchtime (from 11 a.m. to 4 p.m.) they are sheltered from the sun.

In the south, blackcurrant grows well, bears fruit in partial shade, most varieties suffer from excessive solar radiation and heat. In the Kuban, despite the fact that the day is shorter than in many other regions of Russia, the amount of light entering the leaves is greater, that is, the total physiologically active solar radiation above. Therefore, even in partial shade, currant leaves receive enough light rays for photosynthesis. Excessive solar radiation heat enhance the process of respiration, the evaporation of moisture from the leaves is faster than it is supplied by the roots. The leaves burn, the currant bushes are depleted during the crucial period of bookmarking and the formation of flower buds. Therefore, it becomes necessary to look for various methods, to protect the bushes from the hot sun, to create a chill for them, to reduce the evaporation of moisture from the leaves.

Good results in protecting currant bushes from direct sunlight in July-August are provided by tall plants - tomatoes, corn, sorghum, and others. They are planted on the south side of the bushes at a distance of 40-50 cm from the crown. By July, they grow up to 2 meters high, so they protect the currants well, take all the heat of the sun on themselves. You can make temporary (July-August) sun screens. Pull a rope or wire onto high stakes of 2.5-3 meters, hang a black film or old sheets. Screens should be placed next to the crown of bushes on the south side. All of these techniques help keep active life bushes in July-August, to reduce the adverse effects of heat, drought on the formation of next year's crop.

Many new varieties of blackcurrant are drought and heat resistant, tolerate Kuban heat and drought well, grow in open sunny places, do not require protection. For example, Altaiyanka, Gulliver, Grape, Venus, Harmony, Shadrikha, Dessert, Olkhina, Grace, Green Haze, Black Pearl, others. For many Kuban gardeners, such varieties of blackcurrant are simply necessary, especially when there is a lack of water for watering the bushes.