Protection of rhododendrons and conifers in winter spring period

Rhododendrons in central Russia experience several periods of crisis every year.

The first such period, of course, winter. Not all rhododendrons are able to survive it. For us, flower growers, this is another lesson: from now on, our botanical acquisitions should be more meaningful and prepared. It is worth planting only varieties and types of rhododendrons that are winter-hardy in our conditions.

Almost immediately after long winter for rhododendrons, a new crisis period begins. Even when the snow melts and the air temperature rises above zero, the soil remains frozen for a long time. And it freezes in our harsh winters to a depth of one and a half meters. It is clear that a thick layer of frozen soil, practically ice, will not thaw in one day. And not in a week.
It's good if it rains at this time. They do not allow the sun to burn and dry the leaves of evergreens. And there is usually no strong wind during prolonged spring, snow-eating rains.

True, the last springs in the Moscow region were very dry and sunny. Moreover, a strong withering wind joined the sunny clear weather. But the roots of plants under such conditions do not work at all. They are unable to absorb frozen water from the soil. Many evergreens, including rhododendrons, therefore do not “prescribe” in our gardens, “that they die from desiccation during the early spring“ crisis ”. And if they survive, they enter the growing season weakened and therefore more susceptible to various diseases, including deadly for them root rot.

The experience of those who have been growing rhododendrons in our conditions for many years indicates that the greatest danger sunburn evergreen species and varieties with red flowers are exposed. Also very winter hardy. Signs of a sunburn are necrosis and a change in the color of the leaf on its periphery from green to brown and withering of the central vein of the leaf, even where the leaf is still green.

Ball-shaped frame shelter for the protection of rhododendrons

Sometimes the sun and wind dry up the flower buds. Not only in evergreen rhododendrons, even in deciduous ones. In this regard, I remember last year. The windy sunny spring withered some of the buds even in resistant species plants. Because of this, on my site it did not flourish as it should, japanese rhododendron. But some hybrid plants proved to be surprisingly persistent during this crisis period. For instance, deciduous variety Juanita(Juanita), which recently appeared on our sale, did not lose a single flower bud. Absolutely reliable once again proved to be canadian rhododendron, which did not lose a single bud, he pleased with flowering in early May.

How to reduce the risk of spring damage to rhododendrons and ensure the full flowering of all flower buds laid in the previous year? We must always remember that spring protection plants is a continuation of their winter protection. Some lovers of rhododendrons do not cover their bushes for the winter at all, relying on the fact that they have planted only winter-hardy and recommended varieties and species in our area. But the winter hardiness of plants does not mean that the spring period will pass painlessly for them.

Winter protection from the cold different kind shelters allows the plant not to cool as sharply and quickly as it happens in the open air. And of course, shelter in our latitudes is impossible to imagine both without snow retention and actually without snow. Below, under the snow, the temperature is ten degrees higher than outside. This means that even if it gets colder to minus 36°C, it will be about minus 26°C under the snow, and many varieties of rhododendrons cultivated today can withstand such a temperature.

It also "works" and the correct spring protection from the sun and wind. It does not allow the plant, for example, to heat up too quickly behind the house, if it suddenly finds itself under the midday spring, already hot sun. The best defense, of course, is right choice landing sites. But not everyone has the opportunity to plant rhododendrons under the canopy of adult pines, on acidic peaty soil, as plants require in natural conditions. In most cases, you have to create these the necessary conditions for plants. And with their own hands. Remember that deciduous trees, even large ones (for example, old apple trees), will not be able to serve as any protection in the spring without foliage. You can place rhododendrons on the north side of the house. I have varieties with red flowers that grow. However, experience shows that in this case they need additional protection. All other bushes summer time acquiring in my favorite penumbra under the crowns of apple and stone fruit trees, in the spring I have additional protection.

Rhododendrons, especially evergreens, are covered with spruce branches, placing it in the form of a hut

Good remedy for rhododendrons - spruce branches. You can treat it differently in the garden. Today there are many people who believe that using branches of coniferous trees from the forest in own garden unethical. Although the same coniferous spruce branches today, without harm to nature, can be easily obtained from ongoing clearings. If it is not possible to bring spruce branches to the garden on their own, then several united gardeners, I think, are quite capable of ordering pine or spruce branches from a truck cutting down.

There is another resource. Annually, bushes and undergrowth are cleared along the roads in the so-called right-of-way. The space without bushes makes the roads safer both for drivers and for wild animals living in the forests, who sometimes suddenly have a desire to take some road and cross. In addition to reliability, spruce branches, as a heater, have one more advantage over other means of protection. Essential oils and other substances found in the needles prevent the development of pathogenic fungi that cause mold and rot.

Shelter of rhododendrons from spruce branches should be removed gradually. If the forecast promises clear sunny weather in the spring, then already removed protection sometimes worth returning. If weather forecasters promise frosts that are detrimental to the flower buds of some completely winter-hardy species, such as, for example, Schlippenbach's rhododendron, then from above it is easy to throw and fix polyethylene film. The signal for the complete removal of the winter-spring shelter from the plants for me is the complete fall of the needles from the branches. In my opinion, both in winter and in spring, rhododendrons are best protected. huts made from pine branches(I fix the broken branches on a support in the form of the letter "P"). By the way, I also covered the first years of the now uncovered star magnolia.

Can do cover made of synthetic or natural burlap. I prefer artificial. Again, for reasons of greater safety in terms of rot. With the help of a construction stapler, it is easy to make protective screens from this burlap. True, they are afraid of a very strong wind. Bushes growing upwards can, with a little tying, be placed entirely in artificial burlap bags. I protect in the same way and some coniferous plants, in particular blue junipers, which also easily "burn" in the spring, and "burned out", it is extremely difficult to recover.

You can very successfully use the so-called "shuttle bags" for this purpose, you just have to cut them from the bottom. The ventilation on top can be adjusted with a zipper.

Of course, synthetic covers spoil appearance garden in early spring. But sometimes you have to go to these temporary troubles. Protected rhododendrons will definitely respond to your care, bloom well and lay many buds for future flowering.

A. Grishin

Rhododendrons are extremely attractive and showy plants widely used in the field landscape design, but, like all the inhabitants of the garden, they have characteristic diseases and pests that are very fond of feasting on this flower. Diseases characteristic of them and non-infectious lesions can interfere with the full development of rhododendrons.

Non-infectious lesions

Winter drying

It is observed after severe winters, with prolonged frosts, the leaves of evergreen rhododendrons, even at positive air temperatures, remain twisted into “tubes” and adjoined to the shoots. This indicates that the leaves during wintering and severe, prolonged frosts lost so much moisture that a large water deficit formed in the plants and the plants themselves are not able to restore normal water circulation. If you do not take any measures, then the leaves dry up, turn brown and eventually the plant dies. What to do in this case, how to save the plant? To eliminate water deficiency in plants in the spring, after thawing the soil, they are watered abundantly and sprayed with water several times a day. This must be done until the turgor is completely restored by the cells and after about 1-2 weeks they acquire a healthy appearance. This means that normal water exchange has resumed in the plants, and they continue to grow normally. To prevent winter drying of rhododendrons, it is advisable to water them abundantly in the fall.

soaking out

Occurs as a result of excessive soil moisture. The leaf blade of rhododendrons becomes grayish-green, dull, the leaves fall off for no apparent external reason. New shoots are soft, the leaves wither, the root ball collapses, although the roots at the root collar are not damaged. Wetting often occurs in heavy, clayey soils due to poor drainage leading to water pooling in top layer soil and insufficient aeration of the root system. Sometimes it happens with abundant and frequent watering after transplantation. Due to insufficient aeration, normal growth and development of the root system and shoots are disturbed in rhododendrons, plants weaken and are affected by fungal diseases. Excessive soil moisture and late top dressing often lead to freezing of rhododendrons in winter, because. under these conditions, they do not stop growing in a timely manner, do not have time to undergo the necessary hardening and prepare for winter.
To create a normal water and air exchange for the root system, it is necessary to ensure good drainage, wetting plants should be transplanted into loose water and breathable soil, watering should be stopped for a while; on hot, sunny days, instead of watering, spray the aerial parts with water. Wetted plants are rather slow to restore their normal appearance.

sunburn

They appear in the spring after severe frosts or at the end of winter with sharp fluctuations in temperature day and night. Brown, dry spots of irregular shape appear on the leaves of rhododendrons. Sunburn can also appear as a brown streak along the main leaf vein. The leaves of evergreen rhododendrons at -3 ° C and below roll up into a tube and slightly fall down the side of the twisted leaf facing the sun, it heats up during the day and freezes at night. In spring, a reddish-brown or brown stripe is visible on the surface of the untwisted leaves along the entire leaf. If the damage is not strong, then with the beginning of the growing season, the signs of freezing disappear, and the color of the leaves becomes normal.

Control measures.

To prevent sunburn, rhododendrons are planted in semi-shaded places or light partial shade is created for them (shelter of plants with spruce branches or non-woven material on the frame). With good agricultural technology, rhododendrons will give a strong increase, and already in the middle of the current summer, the plant can partially restore its decorative effect.

Chlorosis

It often happens when soil pH is above 7. In an alkaline environment, iron and magnesium are in an indigestible form (even if they are in sufficient quantity), which disrupts the synthesis of chlorophyll. The leaf blade between the vascular bundles (veins) becomes light green or yellowish green. At first, the veins retain a dark green color, and then turn yellow. With severe chlorosis, young shoots turn yellow or pale yellow. Plants grow poorly, often get sunburned, get sick and eventually die.

The cause of chlorosis can also be an excess of copper and calcium in the soil. With an excess of calcium, the normal assimilation of other elements by the plant is disrupted. With its lack, leaf blades can sometimes turn yellow. The bronze-violet color of the leaves of rhododendron occurs with a lack of phosphorus, and the reddish-violet color of the leaf surface and twisting of the edges - with a lack of potassium.

To eliminate chlorosis that has arisen in violation of the acidity of the soil, it is necessary to bring the pH of the medium to 4-5 in order to restore mineral nutrition plants. With a lack of iron, foliar and root fertilizing with iron in a chelated form (ferovit, iron recomchelate, etc.) is carried out. With a lack of magnesium, foliar top dressing is carried out with a solution of magnesium sulfate. After treatment of plants in 5-6 weeks, the leaves are restored green coloring. With a lack of other microelements, they are fed with the corresponding microelements in a chelated form. With their excess, it is advisable to replace the planting soil.

nitrogen deficiency

The entire leaf blade of rhododendrons becomes light, new shoots grow weakly, small leaves develop on them, flower buds are not laid. midsummer leaves previous years begin to turn very yellow, then become reddish-brown, and most of them fall off. By the end of summer, only the leaves of the current year remain on the plants. Nitrogen starvation in rhododendrons often occurs when grown on light sandy soils. With abundant regular watering, mineral salts, especially nitrogen compounds, are washed out and a deficiency of nutrients is created.
When the first signs of nitrogen starvation appear, fertilizing with nitrogen fertilizers (ammonium sulphate or potassium nitrate) is carried out.

Necrosis

The main vein of the leaf dies, the upper side of the leaf turns brown. Necrosis can be caused by a sharp drop in air and soil temperature (especially pronounced in insufficiently winter-hardy rhododendron species), strong winds, drought, and high salt content in the soil. So, excessive application of nitrophos creates an excess of phosphorus in the soil, negatively affecting plants (iron is not absorbed).
With a high salt content in the soil, complete replacement soil or transplanting rhododendrons to another place.

Infectious lesions fungal diseases

leaf spot

Both young seedlings and adult plants are affected. The size, shape, color and location of the spot are diagnostic features.
cercosporosis(pathogen - Cercospora rhododendri) - spots are angular, dark brown with reddish edges, especially noticeable on the underside of the leaf. At high humidity the upper side of the leaf blade is covered with a gray bloom.

Anthracnose(causative agent - Glomerella cingulata [=Colletotrichum gloeosporioides]) - brown spots on leaves and shoots with orange pads of sporulation of the fungus. Severely affected shoots and leaves dry up.

gray spotting(pathogen - Pestalotia guepini) - the spots are large, dry, light brown or gray, often concentric, limited to dark, later black sporangia. Young shoots are also affected, which leads to their death.

gray spotting(causative agents - Phyllosticta rhododendricola, Ph. con-centrica, Ph. saccardoi) - spots are gray, small, with a narrow brown border. Pycnidia of the fungus are formed on the spots in the form of scattered, small, black dots.

yellow-brown spotting(pathogen - Ramularia tumescens) - spots on both sides of the leaf: on the top - yellowish-brown, on the bottom - lighter, often almost white.

Septoria(causative agent - Phloeospora azaleae [=Septoria azaleae]) - spots are yellowish, red-yellowish, small with black dots of pycnidia in the center.

Control measures.

Collection and burning of diseased and fallen leaves. During the growing season, in case of repeated severe damage to the leaves - 3-fold spraying from the moment the first spots appear (end of June) with a Bordeaux mixture of 1% and other copper-containing preparations, 0.2% foundationol. To prevent burns of young foliage, plants with fully matured foliage can be sprayed with copper-containing preparations.

Gray rot (pathogen - Botrytis cinerea). Flowers, stems, leaves are affected, which turn brown and in conditions of high humidity are covered with a gray fluffy coating.

Control measures.

Timely removal of faded flower stalks. Pruning severely affected leaves and buds. When the first signs of the disease appear and favorable conditions for the development of gray rot, fungicide treatments are carried out: sumilex 0.1%, foundationol 0.2%.

powdery mildew(causative agents - Erysiphe rhododen-dri, Phyllactinia guttata). Separate rounded spots appear on the leaves, covered with a white bloom, then, merging, they form a powdery coating that spreads to the entire surface of the leaves.

Control measures.

Top dressing with phosphorus-potassium fertilizers, which increase the resistance of plants to powdery mildew, and limiting nitrogen fertilizers. Spraying with fungicides: topaz 0.4%, bayleton 0.05%, foundationazole 0.2%, topsin M 0.1%. The first treatment is carried out when a spiderweb mycelium or its small spots appear on the leaves, the next 2-3 treatments - after 2-3 weeks, alternating preparations, until the end of August.

Rust(pathogen - Chrysomyxa rhododendri). In autumn, on the underside of the leaves, on pink or purple spots, yellow powdery pustules of urediniosporing of the fungus appear. If the plants are heavily infected, they shed their leaves prematurely. In spring, dark red velvety pads of teliosporing of the fungus are visible on the leaves.

Control measures.

Collection and burning of affected leaves. Spraying during the growing season with topaz 0.4%, Bordeaux mixture 1%, bayleton 0.01%. The frequency of treatments depends on the nature of the outbreak and the weather conditions of the season. In a weak focus and in unfavorable weather for the development of rust - in wet and cold summers - 1 treatment in early to mid-July is enough, at the time the first yellowish mosaic spots appear on the lower leaves of the most susceptible plants. In other cases, 2-3 treatments per season are recommended.

wax disease, its other names are exobazidia, leaf swelling, thick leaves. Caused by various species of Exobasidium fungus. On diseased leaves and shoots, fleshy, pale, waxy gall-like formations appear in the form of a ball ranging in size from a pea to walnut. On leaves affected by E. vaccinii, large spots are formed, covered with a reddish, waxy coating, representing a layer of basidia with basidiospores.

Control measures.

Cutting and burning the affected shoots along with the leaves. Spraying for prevention with copper-containing preparations in the spring - before flowering and after flowering.

Rot of seedlings and young seedlings(causative agents - Rhyzoctonia sp., Pythium sp. and Botrytis sp.). Sudden mass wilting of seedlings and cuttings of rhododendrons, their decay and death.

Control measures.

Creating conditions favorable for plant growth, providing drainage, moderate watering, slightly acidic reaction of the soil solution. Destruction of affected plants along with a clod of soil, disinfection of these areas with lime or ash. Spilling under the root and spraying with foundationazole 0.2%.

root rot(pathogen - Phytophthora cinnamomi). At the base of the stem lower leaves turn yellow, fade, dry up; apical buds turn brown and die, plant growth slows down. On transverse sections of shoots, a brown layer of cambium is visible. The roots turn brown and rot, as a result of which the whole plant dies. Root rot is also caused by fungi of the genera Fusarium, Cylindrocarpon.

Control measures.

The same as with the rot of seedlings and young seedlings.

Necrosis(causative agents - Phoma azaleae, Myxofusicoccum azaleae). Ring or local necrosis is formed on the branches. In the thickness of the cortex of the affected areas, pycnidia are formed.

Control measures.

Creation good conditions for plant growth. Pruning and burning of drying branches, treatment of pruning sites with a solution of copper sulphate 3-5%. After pruning, crown treatment with Bordeaux mixture 1%. For sleeping kidneys, spraying with a solution of copper sulfate 3-5%.

Viral diseases

leaf mosaic(causative agent - Rhododendron mosaic virus). Mosaic spots and swellings form on the leaves.

Control measures.

Destruction of diseased plants, control of vectors: aphids, bedbugs and other insects.

Control measures.

Rejection and destruction of diseased plants. Soil disinfection.

Information from the website "Magic of Nature":

Quite a lot has been written about rhododendrons at the present time, but, oddly enough, there are no fewer questions related to their cultivation.
Rhododendron is one of the most beautiful flowering shrubs in our gardens and parks. This family is very ancient. His ancestors appeared on earth about 50 million years. Currently, the genus includes more than 1000 species, on the basis of which about 12,000 varieties with a wide variety of qualities have been obtained.
Translated from Greek, "rhododendron" means rosewood. Plants of this species belong to the extensive heather family. Among the rhododendrons there are trees up to 20 m tall, however, shrubs from 0.3 to 3 m predominate.
These flowering shrubs began to be cultivated in the 15th century, the bulk of hybrids and varieties appeared in the 20th century. Rhododendrons differ not only in the variety of flower colors, but also in the size, shape of the bush, there are evergreen and deciduous. In autumn, deciduous shrubs delight the most bright colors foliage: from yellow, orange to fiery red and purple.
The rhododendron is especially effective during flowering, which occurs before or after the leaves bloom, sometimes simultaneously with it. In the middle lane flowering various kinds and varieties continues from May to July.
The homeland of most of the known species of rhododendrons (over 700) is East Asia - areas of large rivers originating in Tibet and heading south through the western provinces of China (Sichuan and Yunnan). From here, the distribution area of ​​​​rhododendrons extends west to Kashmir, north and east through Korea, and Japan to Kamchatka, the East Siberian and Okhotsk Seas, south to New Guinea (300 species) and northern Australia. As you move north from China, the number of species of rhododendrons decreases. In the tundra of Eastern Siberia, in Kamchatka, the Kamchatka rhododendron is found, and the Arctic regions of Scandinavia, Greenland and Alaska are the boundary of the growth of rhododendrons. Only one winter-hardy species grows here - the Lapland rhododendron. Only 10 species of rhododendrons are found in Europe. V North America 29 species of rhododendrons, growing mainly along the coast of the Pacific and Atlantic oceans. Rhododendrons are not found in South America and Africa.
Based on data on the occurrence of wild species in nature, German dendrologists I. Berg and L. Heft propose to identify the main areas of distribution of rhododendrons:
1. Himalayas, Western and Central China.
2. Coastal regions of China.
3. Northeast Asia.
4. Japan.
5. Malay Archipelago.
6. Europe.
7. North America.
Most species grow in mountainous and coastal areas adjacent to the oceans, seas and rivers and are characterized by increased rainfall and humid air. Soil conditions play an equally important role for the normal development of rhododendrons, which require a loose, humus-rich, water- and breathable substrate. For most types of rhododendrons, the soil ph is 4.5-5.5, but 4.7 is optimal. Obviously, the need for acidic soils due to the formation of mycorrhiza, the development of which requires an acid reaction of the environment. With regard to light conditions, it should be noted that rhododendrons naturally grow both in open, lit areas, and in shading in the undergrowth. Various Requirements to the light expand their possibilities practical application in landscaping. For the successful introduction of wild species of rhododendrons into the culture, it is necessary to know their geographical distribution and requirements for environmental conditions.
Rhododendrons look very impressive in single and group plantings, they are widely used as components in compositions with coniferous trees and shrubs. undersized species planted on alpine slides, rockeries and gravel gardens. Rhododendrons medium size can be planted at the edge, a hedge along the path. For planting on the lawn, medium-sized shrubs and groups of them are suitable, as well as high views with a beautiful crown. Rhododendrons look good with various ferns, ground cover plants, with small bulbous plants.
Rhododendrons in natural conditions very often grow in the mountains. Sometimes they occupy such vast territories that during flowering it seems that a fire is blazing around! But a rare opportunity to look with one eye at such a miracle. In the photographs, thickets of Japanese rhododendron (Rhododendron japonicum (Gray) Suring.), These photos were taken in his homeland in Japan.

Below are descriptions of fairly winter-hardy species and varieties of rhododendron that can be recommended for cultivation in central Russia:

semi-evergreen species.
Rhododendron Ledebour (Rh. ledebourii). Blooms in April-May. The flowers are pinkish-lilac, the height of the bush is 0.5-1.8 m. In winter, the leaves remain on the bushes and fall in the spring with the beginning of shoot growth.

Evergreen species.
R. ketevbinsky (Rh. catawbiense). Blooms in late May-June. The flowers are lilac-purple, the height of the bush is up to 1.5 m.
R. Smirnova (Rh. smirnowii). Blooms in May-June. The flowers are pink, the height of the bush is up to 1.0 m.
R. short-fruited (Rh. brachycarpum). Blooms in June-July. The flowers are white or slightly pinkish, the height of the bush is up to 1.0 m.
R. largest (Rh. maximum). Blooms in June-July. The flowers are white or pink, the height of the bush is about 1.0 m.
R. golden (Rh. asheitis). blooms in May-June. The flowers are light yellow or golden, the height of the bush is up to 0.3 m.

R. blushing (Rhododendron russatum)
Evergreen cushion shrub, up to 1 m high, crown diameter up to 0.8 m. It grows slowly. The leaves are small, lanceolate, up to 3 cm long, dark green above, reddish-brown below, densely scaly. Blooms from late April to May for 25 days. The flowers are dark purple with a white throat, diameter up to 2.5 cm, odorless, collected in 4 - 5 pieces. Photophilous. Prefers acidic, moist, well-drained soils. Completely winter hardy. One of the most beautiful abundantly and annually blooming ornamental shrubs. Used in rock gardens.

R. small (Rhododendron minus)
Evergreen rounded shrub with a dense crown, up to 1 m high, up to 1.5 m wide. The leaves are dark green, elliptical, leathery, shiny, 4-10 cm long. Flowers 2.5-3 cm in diameter are pale pink or carmine pink , collected in inflorescences of 10-15 pieces, blooms in June, Prefers slightly acidic, rich soils and a bright location. It is frost-resistant, it is recommended to cover young plants for the winter

R. dense (Rhododendron impeditum)
Evergreen, very dense, low cushion shrub, in nature and culture from 0.1 to 0.7 m tall. Shoots are short, densely covered with black scales. The leaves are small, broadly elliptical, 1.5-2.0 cm long, up to 1 cm wide, scaly on both sides. The flowers are small, violet-blue, 2.0-2.5 cm in diameter. Blossoms in May - June, often again in August - September. One of the most valuable small-leaved and small-flowered evergreen species of rhododendron. Grows best on rich, fresh or wet soils. Photophilous, but tolerates slight shading. Mature plants hibernate under the snow, are quite winter-hardy, bloom profusely every year.
Single or group plantings are recommended for low rocky areas and alpine hills, curtains on lawns, in borders.

R. rusty (Rhododendron ferrugineum)
Slow growing low, cushion shrub. Height 0.7 m, crown diameter up to 1 m. The bark is grayish-brown. The leaves are leathery, ovate, 3-4 cm long, up to 1.5 cm wide. Dark green above, shiny, below with rusty scaly glands. Flowering continues from late May to late June (30 days). The flowers are pink-red, rarely white, up to 2 cm in diameter, collected in inflorescences of 6-10 pieces.
Photophilous. It tolerates calcareous soils, but covered with a thick humus layer, preferably acidic (pH 4.5). Quite winter hardy. Alpine slides, single and group plantings on the lawn with the participation of rusty rhododendron will decorate any garden.

R. carolinian (Rhododendron carolinianum)
Evergreen shrub 1 - 1.5 m high. The crown is wide-round. The bark is light brown. The leaves are elliptical, dark green, b-10 cm long, 3-4 cm wide, glabrous above, densely covered with scales below. Blooms in May - June for about 3 weeks. The flowers are white or pink, about 3 cm in diameter, 4-9 per inflorescence, funnel-shaped, with a yellowish spot. It grows slowly, the annual growth is about 5 cm. Light-requiring. Soils prefer slightly acidic, light, moist. Winter-hardy (up to -30 0C). In gardens planted in groups and singly on rocky areas.

R. Daurian (Rhododendron dauricum)
Deciduous or semi-evergreen, strongly branched shrub up to 2m. height. The leaves are small elliptical, densely covered with glands. The flowers are pink in various shades, rarely white up to 4 cm in diameter. Blooms from late April to May before the leaves open. The undoubted advantage of the species is its high winter hardiness (up to -32 0C), but it can suffer from late spring frosts during flowering. Recommended for growing on the edges and in small groups under the canopy of light coniferous species, such as larch.

R. yakushimansky (Rhododendron yakushimanum)
Slow-growing compact, spherical shrub, 0.5-1 m high, crown diameter up to 1.5 m. The leaves are elongated, 5-10 cm long, 3-4 cm wide, leathery, dark green above, bottom with a dense dark brown felt pubescence. Flowering is abundant and long: from May to early June. The flowers are pale pink at first, later white, up to 6 cm in diameter, collected in b - 12 pieces.
Photophilous. Soils prefer fresh, peaty, rich in humus, slightly acidic or acidic. It is winter-hardy, withstands winter frosts down to -22/26 0C, depending on the variety, but it is better to cover the plants at a young age. Recommended for rock gardens, group landings in rock gardens.

Deciduous species.
R. Japanese (Rh. japonicum). Blooms in late May-June. The flowers are salmon-red, the height of the bush is 1.0-1.5 m. There is a form with yellow flowers.

R. yellow (Rh. luteum). Deciduous branched shrub, 1-2 m tall, growing strongly and reaching a width of 2 meters. The flowers are small, very fragrant, yellow or golden-orange, collected in inflorescences of 7-12 pieces, bloom before the leaves appear or simultaneously with them, in May - June. The leaves are oblong-elliptical and oblong-lanceolate, finely serrate and ciliate along the edge, covered on both sides with scattered adpressed glandular bristly hairs. In autumn, the leaves have a beautiful color: yellow, orange, red. It grows relatively quickly, is frost-resistant, requires moist, humus-rich soils, and does not tolerate dry air. Gives abundant root shoots. The large intraspecific variability of this plant attracts the attention of breeders. Most modern varieties of deciduous azaleas come from the Pontic azalea.

R. Canadian (Rh. canadense). Blooms in May. The flowers are purple-violet, the height of the bush is 0.5-0.8 m. There is a form with white flowers!
R. Schlippenbach (Rh. schlippenbachii). Blooms in May. The flowers are white or pinkish, the height of the bush is 1.0-1.2m
R. Vasey (Rh. vaseyi). Blooms in May. The flowers are white pinkish, the height of the bush is 1.2 m.

R. Kamchatka (Rh. camtschaticum). Dwarf bushy shrub, slow growing. The maximum height in culture is 20-30 cm, width - 30-50 cm. The shoots are rough, strongly glandular-hairy at a young age. The leaves are obovate, up to 2.2 cm long, fresh green, red or yellow in autumn. Very beautiful at the time of flowering - from June - July to autumn. The flowers are dark pink or crimson-purple, 2.5-5 cm in diameter, with dark specks, solitary or collected in inflorescences of 3-5 pcs. Frost-resistant species (up to -30 0С), undemanding to soils. Recommended for rock gardens, small gardens, ideal in compositions with heather. It is better to plant in sunny places, the soil prefers well-drained, poor, loose, with a neutral reaction.

R. pukkhansky (Rh. khanense). Blooms in May-June. The flowers are pale lilac-purple, the height of the bush is 0.8 m. Young plants require shelter for the winter.

Those planted in the sun are more likely to be attacked by ailments than those that are in partial shade. Proper agricultural practices increase the resistance of the plant, but the threat still remains. In the article, we will consider why the leaves suddenly dry, the buds darken or the buds die, as well as the main diseases that these are susceptible to.

The first symptom is the beginning of the process of decay of the root system. Mushrooms block the path to nutrients, as a result of which the vascular system of the plant suffers.

It turns brown and dries up, leaves with petioles fall off, and a gray-white mycelium appears on the bark. The root is gradually dying. The remains of the plant continue to store the infection.

If the bush is sick, it is necessary to cut off the infected areas and burn them without delay. Treat the entire plant with. Prevention is carried out by spraying the bushes and watering their root zone with a 0.2% solution of the drug.

Occurs due to the jamming of the rhododendron or a poorly performed basal. In addition, late blight rot can be brought to the garden plot along with an unhealthy shrub purchased from the nursery. The disease begins with the withering of the foliage without the possibility of its restoration.

The root becomes brown and rots. The branches begin to turn yellow, and then the entire rhododendron. The root neck and the base of the stems are covered with brown spots with a purple tint, on which dark gray spores of the fungus develop. The bush withers and dries, but its remains and the soil around it retain the infection.

At the initial stage of the defeat of rhododendron, it is necessary to start regular processing, or 0.2%. Heavier plants should be burned with roots and preventive maintenance of healthy bushes.

It manifests itself by the formation of growths of a rounded shape of a significant size on the roots and root neck. These formations become darker and harder over time.

The bush slows down in growth and loses its flowering power. Further, the growths, together with the root collar, begin to rot, the plant dies, but its remains continue to store the infection.

As with phytophthora rot, bushes that show initial symptoms should be treated regularly. Bordeaux liquid or other similar drug. In case of severe damage, burn the plant along with the root system.

Gray and other rot

Rhododendron can be affected by a variety of rot:

• gray;
• seedlings and young seedlings;
• buds;
• root;
• dry white;
• shoot death.

appears on the foliage, stems, buds and petals of the plant in the form of blurry brown spots without a border.

The surface coating gradually dries and begins to crack. At high humidity, parts of the bush affected by necrosis are covered with a fluffy smoky-gray spore coating. After some time, the drying mycelium is filled with brown rounded sclerotia.

You can cope with rot only by cutting off the affected areas of the rhododendron. For preventive treatment spray the plant with a 0.2% solution of the "Fundazol" preparation, and also pour it over the root zone.
for a rhododendron, it begins with withering and ends with death. White spores of fungi or mold form on its leaves. Brown, and the surface is covered with threads resembling a web.

Sprinkle the seedlings that have begun to die with crushed or powdered "Fundazol" preparation. In addition, for the purpose of prevention, it can be treated with a 0.2% solution of the drug "Fundazol".
The buds turn brown and die off, after which the mycelium grows into the branches. You can limit the development of the disease by removing dark buds and dry shoots. While the plant lives, spray it every two weeks with preparations that contain.
threatens shrubs growing in the shade. Buds at the top of the bush will not bloom. Instead, their color will turn brown and the process of dying off will begin. Following them, the leaves will begin to curl up, acquire a brown color and dry. If severely damaged, the plant will die. The disease can also begin with the drilling of leaves on some shoots. Then they will begin to dry, after which the entire shoot will die.

You can cope with the death of shoots by burning the affected foliage and shoots. As soon as the rhododendron fades, you should begin its regular (every two weeks) treatment with copper-based preparations.
affects the roots and stems at the base. But first, the foliage withers and dries for no reason. The buds then turn brown and die. Immediately before the death of the rhododendron, the root system becomes brown and rotten.

To cope with the disease, it is necessary to burn the affected areas of the plant or the entire diseased bush. It is possible to protect rhododendron from root rot. Maintain at the level that your particular variety needs, and follow the watering rules.
wraps around the root neck of the plant and looks like a gray-white ring. The well-known mushroom causes the defeat - it is its mycelium that grows in weakened rhododendrons. As a result, the bush dies. Strongly growing rhododendrons do not suffer from such a disease.

The affected plant must be dug up and burned, and the bushes near it should be transplanted.

Several types of fungi can provoke wax disease, which:

1. Cause slight deformation with thickening of the leaves. They are covered with large spots of red or red-brown color, round or elongated. A waxy coating of spores appears in the area of ​​necrosis. As a result, the stains dry and crack.
2. form white cushion-like growths on the young foliage of an evergreen shrub.
3. Cover the leaves with round spots. On their back side, one can observe the development of white spores.
4. Change the color of the foliage to yellow-brown. A powdery coating appears on the back of the leaf, after which the process of dying begins.
5. Leaves and shoots are affected. Huge pale green leaves of abnormal thickness begin to grow on the rhododendron. They are covered with a white coating. The sheet begins to wrinkle, mold and dry.

Cure for wax disease the plant can be done by trimming the affected areas, as well as by treating with Bordeaux liquid or the Cumulus preparation. Processing is best done in the spring.

Various spotting

Pestalocium blotch affects foliage and stems. Brownish spots of irregular shape appear on them. They are framed by a thin brown border. Smaller spots on leaves than on stems. Gray pads with spores appear on top of the spots.

Did you know? Honey from the nectar of some rhododendrons has hallucinogenic and laxative properties.

The rhododendron disease, which is shown in the photo, “changes” the color of the stems to brown and stains the foliage, so its treatment occurs by trimming the affected parts, followed by treating the bush with a Bordeaux solution or Camulus.
are identified by brown spots in the upper part of the leaf, followed by its drying. Rounded dark bodies with spores form on the spots. Following the leaves, the stems fall ill.

Treatment of anthracose spotting is based on cutting the lesions and spraying with Bordeaux liquid.
affects the foliage of rhododendron. It is covered with rounded red spots. After a certain period of time, black dotted fruits of the fungus appear on the spots. After that, the foliage turns yellow and dries.

The disease of rhododendron, which is shown in the photo, is distinguished by the formation of spots of black fruiting bodies of the fungus on the surface, therefore, its treatment occurs by cutting off the affected areas and treating the shrub with a Bordeaux solution or the Camulus preparation.

Important! Spraying plants with preparations with copper at high humidity threatens leaves and shoots with burns.

diagnosed by the condition of the leaves. A characteristic symptom is the appearance of large round spots with a red border. Black sporangia begin to roll out of them. Then the leaves die.

The framing of the spot may also be brown, depending on the type of pathogen. Over time, the lesion brightens, cracks and crumbles. In this case, it is necessary to cut off the affected parts and treat the bush with Bordeaux liquid or the Camulus preparation.

The discovery of rhododendrons and roses this year is a cause for sadness. For the first time in over 10 years, my rhododendron has died out. I assumed a bad outcome for the plants after this winter, and now the predictions began to come true.
This is how the frozen Nova Zembla rhododendron looks like.

Freezing is characterized by a dull color and damage not from the direction of the sun, but more from the north side or from all sides.

Here you can see the difference from the burnt rhododendron. The leaves of the burnt rhododendron are brown, the plant burns out on the south side.

What to do with a frozen rhododendron

If the rhododendron is severely damaged by frost, then it is necessary to shed it thoroughly and a little later, when the earth finally thaws, it is necessary to cut off the dead shoots and wait for new shoots. Winter-hardy varieties have a chance to recover. But, unfortunately, this is only a chance - if the plant is very frostbitten - it will die. My rhododendron is very frostbitten. As you can see in the photo of intact leaves, no more than a dozen. It's bad, but I still hope for a happy ending. Using the example of this rhododendron, one can well understand what frost resistance is. 4 rhododendrons survived the winter with no or very little loss, and one rhododendron is near death.

Photo from April 09, 2016 of rhododendrons - Helsinki University (upper photo next to the frozen rhododendron)

Below are photos of rhododendrons by Katevbinsky, Cunningham White, The Hague. They all look good, the damage is small, but they are extremely minor.

Minor frost damage near The Hague

The American Rhododendron Association gives Nova Zembla a frost hardiness of -32C. This is a very high frost resistance, for example, the Katevbinsky Grandifloum is only -26C. However, Zembla is frozen, and Grandiflorum stands still, as if there were no frosts.

I watered the frozen rhododendron thoroughly with water from a forest ditch, and left a light cover so that the sun would not burn the already unfortunate plant. I will cut a little later - most likely next week.

With the rest of the rhododendrons, the shelter was completely removed.