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Video: Dahlias - Protection And Storage. Tubers. Photo
Dahlia leaves in dry autumn weather tolerate short-term frosts down to -0.5 ° - -1 °. Only some darkening is observed. Dahlia stems endure short-term frosts up to -2 °. In the middle lane, the onset of the first frosts on average falls on September 8-17, and early frosts are often observed in early September. Sometimes by September 10 they reach -4, -6 °. At this temperature, not only leaves, buds and inflorescences die, but also stems.
When dahlia stems are damaged, the roots, like powerful pumps, continue to supply juice with dissolved nutrients to the aerial part, and capillaries damaged by frost cannot supply them to the leaves, circulation is disturbed, the juice accumulated in the lower part of the stem begins to decompose, which leads to decay of the dahlia neck and the whole tuber. Therefore, if the stems are severely affected by frost, it is urgent to start digging dahlias.
Usually, after short early autumn frosts, good weather still lasts for a long time, sometimes up to a month. Therefore, it is advisable to take all possible measures to protect plants from the first frost. There are many ways in which you can protect dahlias from frost: sheltering plants, heating fires, stoves, etc. But all of them are very expensive, labor-intensive, or unreliable. The most common method of fighting frost - a smoke screen - often, especially in windy conditions, does not give the desired effect.
A simple and effective way to protect plants from frost is sprinkling, the protective effect of which is based in general on the following. The water in the water supply system or wells has a temperature of at least + 6 ° and when it drops by 1 ° 1 m 3water releases 1000 large calories of heat. Sprinkling itself increases the humidity of the air, which, in turn, reduces the radiation of heat from the soil and plant. At the same time, the wetted soil, due to the increase in thermal conductivity, gives off heat to the surface air layer. The water settling on the surface of the plants freezes, gradually dressing it with a very thin but dense ice crust. The temperature under such an ice shell does not go below -0.5 °. Ice saves the plant from frost. During thawing, evaporation is slower and accompanied by heat absorption. This promotes the slow melting of ice in the intercellular spaces and the absorption of water from them by the protoplasm of the cells.
The following experiments were carried out in the Main Botanical Garden in the fall of 1959: a sprinkler was equipped on the dahlia site. During the growing season, it was used for irrigation, during frosts - for plant protection by sprinkling. Water was sprayed with nozzles with a range of 3.5-4 m. The sprayers were connected with a soft hose to the water supply network and were installed at a distance of 8 m from each other along the centerline of each rabat at a height of 1.5 m. Sprinkling began at 0 ° and continued until until the temperature rises above 0 °. At an air temperature of -4 °, the plants were covered with a layer of ice.
Measurements showed that the air temperature in the sprinkling area was always 2 ° higher than in non-irrigated areas.
Despite the fact that the air temperature on September 28 dropped to -6 °, the dahlias in the sprinkling area after thawing were intact, while the control plants died.
Weaker frosts on September 30 and October 3 did not even cause the formation of an ice crust, although the temperature in the air in the unprotected area reached -3 °. Until stable night temperatures were established, good inflorescences were cut from these plants. The analysis carried out after the tuber digging showed that the plants protected by sprinkling in 12 days after the first frost gave a significant increase in the weight of the tubers in comparison with the control ones.
Sprinkling method lengthens the growing season of plants in the open field. It should be widely used in floriculture.
Cleaning and storage of root tubers
Before the onset of severe cold weather, when the first severe frosts will beat most of the dahlia leaves, it is urgent to start digging root tubers.
Usually dug in late September - early October in good weather at freezing temperatures, so that the root-tubers can be well ventilated. It is better to dig it before noon, since 3-4 hours before the evening they will dry out and by the evening they will be ready for cleaning. To dig a dahlia, you need to have two digging good shovels or two garden forks, a garden hacksaw, a pruner for cutting stems and a knife for cutting garters. First, the stems are cut from several plants, for example, from 2-3 rows, then the stakes are removed, the labels are removed. After that, the root tubers are dug out of the ground and the labels are tied. When digging, you must try not to damage the root tubers. To do this, retreating from the remainder of the stem (hemp) by 15-25 cm, dig in the root-tuber from all sides, carefully raise it, holding it by the stump,lightly remove the ground from above with your hand and carefully remove. You should not lift and shake the tuber from the ground by the stump. This can damage the necks of the root tubers. A fracture of the neck at the junction with the root tubers, as a rule, leads to the death of the root tubers in winter.
On heavy clay soil, it is better to dig up tubers together with a garden pitchfork or two shovels from opposite sides, retreating from the hemp by the length of the tubers. The root tuber with the help of a garden pitchfork or two shovels is lifted vertically upward with a large lump of earth and carefully placed on a level place, slightly shaking off so that most of the earth flies around, the rest of the earth is shaken off with a light blow of the palm or a wooden stick on the stem (hemp). It is better not to shake off the soil from weak tubers. When the root tubers are a little weathered and the cuttings of the stems slightly dry out, they are removed for storage right with a lump of earth. If the root tubers are to be stored in a storage with high humidity, the root tubers are dried more thoroughly.
Winter storage of dahlia root tubers is a responsible and serious period. There are many old dahlia varieties in culture, which form excellent large dense root tubers that can be stored in the winter in any conditions. However, recently created by Russian and foreign breeders, new hybrid varieties of dahlias, which are significantly superior to the old varieties in color and elegance of the shape of the inflorescences, are often inferior to the old varieties in durability during storage. True, subject to certain storage rules, new varieties are well preserved.
The best mode for preserving dahlia root tubers is a temperature of +3 - + 6 °. Particular attention should be paid to the air humidity in the storage, which should be maintained within 60-75%. Where possible, the dahlia storage should be ventilated by opening vents or periodically turning on a portable or stationary fan. The periodic movement of air in the storage facility allows maintaining its uniform humidity, which largely prevents the development of fungal diseases.
Before laying root tubers for winter storage, it is necessary to disinfect the storage in advance by fumigating with sulfur at the rate of 50 g of sulfur per 1 m 3 of the room volume. During fumigation, the store must be closed, all openings tightly sealed. After that, it is good to whitewash the storage with a solution of bleach or freshly slaked lime.
Dahlia root tubers should be stored in one or two rows on dry ground, sand or wooden shelves.
During the winter period, at least once a month, the root tubs of the dahlia should be inspected and, depending on the nature of the damage found, appropriate measures should be taken. The death of root tubers in winter can often be the result of poor ripening (with thickened planting or growing on damp cold soil, especially in low places), as well as the negative effect of the first frosts, in dahlias with uncooked root collars, from excessive feeding, especially multiple fertilizing with mineral fertilizers with a high nitrogen content. In plants that grow and bloom well, the neck tissues and tubers are loose, unripe. The root tubers of these plants are usually poorly preserved.The safety of root tubers in winter also depends on climatic conditions - in a very dry or rainy summer, the tubers do not receive the necessary nutrients and do not have time to mature enough; from the conditions of their digging - in frosty weather, when snow begins to fall, or in rainy weather it is more difficult to dig, the tubers are wet, heavy, break off easily and rot in storage. The preservation of the root tuber also depends on the varietal characteristics of the plants.
Correctly taking into account all these factors, it is possible to achieve almost complete safety of all dahlia root tubers.
Among amateurs and flower growers, many different methods have been developed for preserving dahlia root tubers. This is natural, because each grower has his own special agricultural methods of growing plants, different soils, different climatic conditions, different storage conditions for root tubers. Therefore, there can be no general rules for storage.
The oldest breeder A. A. Grushetsky, without a special storage, kept dahlia root tubers in room conditions at a temperature of +12 - + 20 °. Dug root tubers, trying not to damage, he shook off the ground and laid out in the greenhouse. With the doors and vents open, he dried them well for 5-6 days, then cut off all the small roots and last year's old uterine tubers, shortened the stems, leaving hemp 2-3 cm long from the neck. Places of cuts were sprinkled with fluff lime or smeared with lime slurry. Prior to storage for a week, he kept root tubers at a temperature of +20 - + 25 °. During this time, fractures and cuts have time to be covered with a cork layer. Then the boxes measuring 80x50x60 cm were lined with thick paper. At the bottom he poured dry crushed earth (3 cm layer). After that, he began to lay the root tubers.After laying, each row of root tubers was covered with earth from above and the box was tightly covered with paper from above. In such packaging, dahlias were preserved almost 100%.
Many amateurs, before laying root tubers for winter storage, process them in a solution of potassium permanganate. A. N. Groth processed root tubers as follows. The root tubers dug out of the ground were immediately immersed in water for several hours (from 3 to 12 hours). Then, with a stream of water or a brush, he washed off the adhering clay soil and cut off all thin roots. After that, he transferred them into a vessel with a solution of potassium permanganate so that the tubers were completely immersed together with the remaining part of the stem. The solution should be dark purple in color. The tubers were kept in this way from 0.5 to 2 hours. As a result, they should acquire a dark golden yellow or light brown color. Eyes and green sprouts, sometimes appearing in autumn, do not suffer from this, even if the color of the root tubers is brought to dark brown. Tubers matured in solution,without drying it, put it in the basement and after 2-3 days covered it with slightly moist clean sand. This method of preparing root tubers for storage ensured almost 100% safety.
An amateur flower grower SG Valikov keeps dahlia root tubers in a half-baked basement in boxes with sand. He thoroughly dries the dug root tubers, cleans them of soil, then removes all small roots, damaged and rotten roots. The stem leaves no more than 8-10 cm from the root collar. Prepares boxes (usually wooden, thin-walled), dries them, covers the bottom and walls with a double layer of newsprint, neatly folds root tubers. Then he covers them with calcined river sand so that there is a small layer of sand on top of the tubers. He covers the boxes from above with paper and puts them in the basement, stacking one on top of the other in two rows. In this position, dahlia root tubers remain until spring.
In winter, SG Valikov monthly makes a superficial inspection of the boxes. When mold appears, he wipes the boxes with a dry cloth. Potatoes, sauerkraut, cucumbers and other pickles are stored in the same basement. The air temperature in the basement ranges from +2 to + 6 °. The relative humidity in the storage should always be elevated, at least 70%. With this storage method, the annual mortality over an 18-year period averaged 4% of the number of laid root tubers.
The storage of root tubers grown from cuttings plants gives flower growers a lot of trouble and grief. Root tubers of cuttings, intensively fed with all kinds of liquid fertilizers with a high nitrogen content, are poorly stored. These plants grow violently, bloom beautifully, but their root tubers are loose, weak, with a large number of small fragile roots. It is better to store such root tubers with a lump of earth, without shaking off, slightly airing and drying in the fresh air during digging. Then the tubers are placed in a basement, well ventilated with air vents. If, however, the ground has flown around from the root tuber, and the tuber is weak, then after light drying it is recommended to put them in a box and cover them with dry peat, earth or sand.
Particularly valuable varieties of dahlias can be propagated and preserved by the method of summer cuttings, rooting all shoots from pinching. Rooted cuttings planted in pots are exposed in a bright place. These plants remain green throughout the winter. Of course, only a small number of plants can be preserved this way.
Cuttings of summer (from June to August) cuttings grown in pots, with the onset of frost, are removed to a warm room, and, if possible, they try to extend the growing season. Then, around the end of October, the stems of cuttings are cut off, and after drying, the pots with nodules are removed to the basement (storage).
SG Valikov conducted experiments on the preservation of nodules grown from plants of summer cuttings. As shown by these experiments, June cuttings give the normal formation of small, but sufficiently formed and ripe nodules that are well stored. He kept them in a half-baked basement in boxes covered with dry low-lying peat or sand. The safety of nodules was 75-85%.
With July cuttings, nodules are much softer and smaller in size. He kept such nodules with stems 10-20 cm long, wrapped them in thick paper, put them in boxes and sprinkled them with peat on top. The safety of root tubers was 60-80%.
Sometimes during June and August cuttings in the open ground, not nodules are formed, but thickenings (callus) and a mass of small roots, the so-called "beard". Such specimens were kept by S.G. Valikov with stems 16-25 cm long in peat. He did not shake off the soil from the dug out plants, carefully removed the leaves, shortened the stem, laid out each copy on paper with peat poured on it, and carefully wrapped it. The specimens prepared in this way were folded into boxes, which were covered with peat on top. With this method, the preservation was about 50%, and during normal storage, or even simply covered with sand or peat specimens with a "beard" were not preserved at all.