What threatens fruit trees and shrubs that are subject to highly variable weather conditions?
Little snow, unstable temperatures, strong and frosty winds are not good for overwintering plants in the garden. Hardy trees and shrubs can also be damaged by drastic fluctuations. How much damage could occur? Can this be prevented and how?
Thanks to the relatively warm end of the year (temperatures in November even reached +15 ° C, in December – about +5 ° C), the garden awoke early from dormancy. Many types of fruit trees have started to bloom – the swollen buds are clearly visible, especially in cherry, currant, plum and quince. The home garden has also been transformed. For example, onion garlic has become too big for this season and has reached a height of almost 10 cm, whereas it should be completely under a layer of snow.
What can threaten plants in the early stages of growth? What to do when the weather changes drastically and real winter arrives?
Danger 1: Frost on the flower buds
A severe drop in temperature can cause plants to deteriorate due to damage to the root layer. The consequences of the process of destruction of trees and shrubs from the inside do not appear immediately, but only after the beginning of the growing season, i.e. in the spring calendar. Then intensively flowering trees and shrubs begin to die just as quickly. If you dig them out of the ground, you will probably immediately notice a dry root layer of unhealthy brown color.
Plant roots also suffer from constant freezing winds if they are not covered well enough. The root systems of trees and shrubs during dormancy are very resistant to very low temperatures (d o 15 °C for young plants up to 2 years old, d o 20 °C for older plants.) ) become increasingly susceptible to the prevailing climatic conditions. You can freeze during the last spring frosts – “Gardener’s Cold”, “Zoska’s Cold” – when the temperature drops to about d o-5 °C. It freezes if Deckerde is too loose or the mounding around tree trunks is too small.
What should you do to protect your plants and keep them in good condition?
Cover the trunks of trees and shrubs closely with a layer (10-15 cm thick, 1-1.5 m wide) of compressed and not fully crushed compost or turf. In this way, they both protect the roots from the cold and provide them with a rich source of micro- and macro nutrients necessary for proper development. Another solution is to cover the roots with leaves or sawdust. In practice, this does more harm than good because it promotes rotting processes that are harmful to ornamental plants.
Threat 2: freezing of branches and twigs
Sudden frost can cause death of above-ground part of fruit-trees, mainly trunk and thick branches. Large temperature fluctuations between day and night are especially dangerous, in which damage can take catastrophic forms – wound ignition or bark destruction, which often reaches the trunk or branches. If the severe drop in temperature is a short-term phenomenon, gangrene goes away on its own. On the other hand, there is the gradual desiccation of trunks and branches over a long period of time, which in turn leads to the death of the entire tree or shrub.
What should you do to protect your plants and keep them in good condition?
Protect the trunks of trees and shrubs for up to two years with a special fleece. A layer of straw and reeds provides equally good protection. Older plants need more intensive care, that is, bleaching. This is one of the most important care measures, which primarily serves to protect the trunks and bark of plants from drastic fluctuations in temperature. However, it offers many more benefits. Bleaching with lime:
- Protects trees from intense ultraviolet radiation, which, combined with temperature fluctuations, causes the bark to crack during the day,
- kills pests with their larvae and eggs, which nest in the cavities of the cracked bark,
- protects trees from animals looking for food.
To properly prepare trees for bleaching, clean them with a wire or rice brush and then spray the trunk twice (within 3 hours) without skipping the crown. First spray with a fungicide that fights mold and fungi, and the second with an oil-based product that kills pests.
Start fertilizing with milk of lime, which you can buy at the gardening business, or with brandy (calcium oxide), which is used in construction, for example. To do this, dissolve them in a proportion of 2 kg per 10 liters of water. To prevent the lime from washing off the trunks too quickly during rain, add a liability-enhancing cloth to the mixture: 10% white dispersion paint. Brush it on both the trunks and the bases of the thicker branches of the fruit trees. Cover the southern side of the plants a little higher, as it primarily requires intense protection from the sun’s rays; although the sun stimulates the sap movement in the tree during the day, it quickly freezes at night – in the event of a significant drop in temperature. As a result, the trunk bursts and breaks, which is associated with brandy wounds.
An alternative treatment with a similar effect as “Thünchen” with lime is to spray trees with a solution of lime and water at a ratio of 1 kg of calcium to 5 liters of water. The sprayed solution reaches the smallest corners of the bark and thus protects the tree from the inside against bad weather. This is an undeniable advantage of the solution under discussion. It is, however, not without its disadvantages, as it can turn out that a thin layer of sprayed lime is not enough to neutralize the pests that are lodged in the bark.
How should you take care of fruit trees and shrubs when instead of calendar winter comes an aura reminiscent of early spring? The most important thing is to constantly monitor the quality of the recommendations and, if necessary, improve thoroughly. Additional maintenance treatments in the form of lime bleaching strengthen plants and increase their chances of survival before a suitable growing season arrives.
Non-infectious tree diseases caused by weather events
In the past, we wrote in the article “Non-infectious diseases of fruit crops” that besides infectious diseases caused by fungi, bacteria or viruses, fruit crops are affected by non-infectious diseases. These diseases are associated with a lack or excess of certain substances in the soil, exposure to meteorological factors, air pollution and mechanical damage to individual organs.
We described the signs of chemical elements deficiency in soil and treatment measures for fruit-trees. Now let’s consider tree diseases related to the influence of weather phenomena.
We immediately find that trees weakened by unfavorable growth conditions, lack of moisture and other factors become more susceptible to infectious diseases and insect damage, and trees mechanically (stem circle, pulling, insects) become more susceptible to unwanted weather conditions.
Trees damaged mechanically (scion, pulling, insects) become more susceptible to unwanted weather conditions.
Protection from Burns.
Spring needle burning of evergreen plants
On sunny days in early spring, moisture evaporation of early spring needles increases and the roots in the frozen soil are not yet able to absorb water. Therefore, when the needles are burned, the plant can die. Spring needle burning is especially dangerous for recently planted plants.
Protective measures: Water, especially from the east, to protect newly planted plants. Also, cover with lutrasil in February.
Spring burning of trunks and branch bark
Early spring temperatures change dramatically during the day. The bark heats up during the day and cools down considerably at night. As a result, sunburns form on the lighted side of trees of various shapes, colors and sizes, more often on the southern and southwestern side of shoots and branches. In these places, the wood dries out, withers, dies off, cracks, which creates conditions for development of necrotic diseases of stems.
Measures of protection: covering trunks and bases of skeletal branches with lime milk. The white color reflects the sun’s rays and thus reduces the risk of uneven bark warming. This measure is best carried out in autumn to protect the tree from the effects of frost and wind in winter. In early spring, it is recommended to refresh the white linen to protect the bark from the sun’s rays, some pests and diseases. To make lime milk, 2 kg of quicklime is diluted in 10 water, 1 kg of sonic and 300 g of copper vitriol.
The boles of young trees in autumn can be tied with white paper or other materials, trees are not only protected from sunburn, but also from rabbits (we will talk about this separately).
Exposure to high temperatures in summer can also cause burns, resulting in leaf fall, wrinkling, steering, and falling fruit. Leaves can dry out quickly when relative humidity is severely reduced and temperatures are high, as well as when the soil is dry and, if lit, in direct sunlight. Leaf scorch is often determined when water collects in the leaf plate after rain (in greenhouses, after watering), which collects the sun’s rays like a lens. In these places, leaf plate tissue is formed, which has a different shape.
Protective measures: Water trees under the root in the evening, mulch to keep moisture in the ground.
Frost rips form in the bark and wood when there are large temperature changes. After all, bark shrinks faster than wood during a sudden change in cold. The tissue turns brown, vessels become clogged, and the movement of water and nutrients is disrupted, causing individual branches to dry out.
Frost rips can extend several meters deep into the heart of the tree. Sometimes, with this observed swelling of damaged wood and bark, pathogens penetrate into the wounds, some species of mucus leaks, determined by gumming (with stone fruits). Tree infectious disease agents accumulate in gum and mucus.
Protective measures: trunk and skeletal branches in autumn and early spring – with lime milk. In early spring (before the beginning of sap movement), it is necessary to have time to heal a tree damaged by frost: cut off retired bark except living tissue, disinfect the wound with 1% solution of copper sulfate and smear it with a sound mixture with fresh cowpea (1: 1).
Spring frosts more often damage trees that are watered late or excessively (especially nitrogen) and weakened by premature pruning. Such trees do not have time to form buds and wood. Therefore, they are susceptible to low temperatures in winter and frosts in spring. In spruce, the central disc bends and laterally matures. Similar damage that is determined in pine is similar to that caused by pine blades.
Spring frosts damage fairly late or over-fertilized trees.
Protective measures: During blooming – watering the soil with water, drip irrigation during frosts. One method of frost protection is smoke (burning organic waste under trees), but care must be taken not to damage trees with streams of hot air.